Drug delivery device for delivering a predetermined fixed dose - Patents.com

Abstract

A medication delivery device (100, 200) for delivering a fixed dose, the medication delivery device comprising: a housing assembly; a medication reservoir having a piston; and a drive mechanism. The drive mechanism comprises a piston rod (109, 209) for advancing the piston to expel medication; and a drive-tube (180, 280), the drive mechanism adapted to deliver a predetermined fixed dose in response to activation. The medication delivery device further comprises an activation mechanism for activating the drive mechanism in response to axial movement of the drive-tube. The housing assembly comprises a guide structure for guiding the drive-tube during activation and delivery, the guide structure comprising an axial portion (156, 256) providing a sliding surface for guiding the drive-tube during activation and for providing a rotational stop that defines the end of the dose, and a helical portion (157, 257) providing a sliding surface adapted to guide the drive-tube (180, 280) during administration. The drive tube (180, 280) comprises a guide structure comprising an axial portion (182, 282) adapted to slidably engage with the axial portion of the housing assembly for actuation, and a helical portion (189, 289) for slidably engaging with the helical portion of the housing assembly during administration.

Description

[Technical field]

[0001] The present invention relates to a drug delivery device for delivering a fixed dose, in particular to such a drug delivery device comprising a drive mechanism having a helix and an axial guide portion. [Background technology]

[0002] Drug delivery devices for self-administration of different liquid formulations currently exist in various shapes and sizes. Some are adapted to connect to an infusion set, others connect to or are integrated with an injection needle. The latter type is called an injection device. Some are durable devices equipped with a cartridge with a drug reservoir, which can be replaced. On the other hand, there are disposable devices that are discarded when the cartridge is empty. Disposable devices can be either multi-dose devices, where the user can set the desired dose size before each injection, or single-dose devices that can only give a single dose of a given size. The latter exist with the so-called "shield activation", where the cannula is covered by a shield on the front of the device that releases the dose when pressed. The cannula is then only exposed to enter the skin when the user presses the device against the skin, thereby depressing the shield and releasing the dose. These injection devices are discarded after a single injection.

[0003] Fixed dose devices are preferred by some users because they may be resistant to or unable to operate the device to adjust the correct dose every time. For example, when the device is used by children or the elderly, simplicity and ease of use are important to avoid user errors that lead to over- or under-dosing. In other cases, the treatment regimen prescribes a fixed dose of, for example, a GLP-1 type drug.

[0004] However, the device itself represents a significant portion of the cost of the unit, not to mention the amount of material used and therefore the need to dispose of. It would therefore be desirable to create a fixed dose device capable of delivering multiple doses of a fixed volume.

[0005] In existing multi-dose devices, the motor consists of a spring that winds up when adjusting the dose. One solution is to make a regular multi-dose device where the maximum dose size is limited, so that it is only possible to dial up to a fixed dose size. However, this would pose a risk that the user will not dial up sufficiently and therefore get a smaller dose than expected, a problem that is solved in US Pat. No. 5,399,433 filed by Novo Nordisk, where a ratchet tube is locked in the housing until the full dose is set and the drive mechanism is released.

[0006] Another fixed dose device is disclosed in US Pat. No. 5,399,633 filed by Sanofi-Aventis. The disclosure relates to an injection device having a longitudinally displaceable dose tracker, providing automatic dose setting according to a preselected dose size. The disclosed injection device comprises an elongated housing 10 extending along a longitudinal axis (z) and a piston rod 20, 120 for operative engagement with a piston 7 of a cartridge 6 filled with a medicament. The injection device further comprises a dose tracker 60, 150, 250, 350, 450, 550 selectively operatively engageable with the piston rod 20, 120, the dose tracker being proximally displaceable relative to the housing 10 from an initial position (i) (see FIG. 25) towards at least a first activation position (a) (see FIG. 26) for setting a dose, and the dose tracker being distally displaceable relative to the housing (10) from the activation position (a) towards the initial position (i) for dispensing a dose. The injection device comprises a spring 80, 144 for biasing the dose tracker in a proximal direction. The injection device further comprises an interlock 84, 184, 284, 584 for locking the dose tracker in the initial position (i) and a release member 100, 101, 190, 290, 590 for releasing the interlock 84, 184, 284. For example, when the release member 190 is activated to release or unlock the dose tracker 150, the dose tracker 150 starts to rotate relative to the housing under the action of the relaxation spring 144. An alternative fixed dose device from which the size of the fixed dose can be selected is disclosed in US Pat. No. 5,399,413 filed by Merch Sharp & Dohme Corp. However, allowing the possibility to select between fixed doses of different sizes increases the complexity of the device and the selection function is not always desirable. The function of providing different fixed dose sizes can alternatively be obtained by using a set of two or more different fixed dose devices.

[0007] An alternative fixed dose device is disclosed in the patent application WO 2005 / 023333 filed by Copernicus. The disclosure relates to an injection device for delivering a defined number of equal doses of a fluid substance. The disclosed injection device comprises a housing 1 having a safety mechanism and a dose delivery mechanism arranged along the longitudinal axis of the housing. The housing is coupled to an enclosure 3 for receiving a reservoir with a fluid substance. The safety mechanism comprises a setting sleeve 5 which is axially non-displaceable. The safety mechanism is rotatable about the axis of the housing by a defined setting angle (a) in two opposite directions. The setting sleeve 5 is coupled to a torsion spring 10 which is tensioned by the rotation of the setting sleeve 5 during the arming of the device. The dose delivery mechanism comprises a screw ring 6 and a piston rod 4 which is non-rotatable and axially displaceable in the setting sleeve 5. When the piston rod 4 cooperates with the screw ring 6, the screw ring 6 and the piston rod 4 are fixed during the arming of the device. During delivery of each dose, the piston rod 4 is displaced along the housing 1 by a defined distance due to the unwinding of the spring 10 and the rotation of the screw ring 6. The displacement of the piston rod 4 causes the fluid substance to be expelled from the reservoir. As shown, the torsion spring must be tensioned to allow the ejection of the dose. An alternative design utilizing spring compression is also described in US Pat. No. 5,399,433 filed by Copernicus. Another alternative device utilizing spring compression before each fixed dose is also disclosed in US Pat. No. 5,399,433 filed by Owen Mumford. However, disarming the device between each dose is not always desirable, as the user needs to provide sufficient force to disarm the device.

[0008] An alternative fixed dose device is disclosed in US Pat. No. 5,399,366 filed by Menarini. The disclosure relates to a device for automatic injection of two doses of a medicament in two successive doses. The disclosure describes an automatic injection device with a sliding sheath 30 which, when depressed with its front end 3 against an injection site, interacts with cam means 26, 27, 28 to activate the trigger of the plunger 8 and control the delivery of the medicament dose. A plunger guide means 44 is provided on the inner surface of the outer housing 1 to control the trigger sequence, and a dose knob 4 is used to arm or set the device in a dose delivery condition. The device is adapted for automatic needle reshielding and resetting of the unlocked condition after each dose is delivered. The number of device components is reduced, resulting in a simpler construction and reduced costs. Devices with similar functionality by the same applicant are disclosed in US Pat. No. 5,399,366 and US Pat. No. 5,399,366. As shown, all alternatives utilize a compression spring as the power means to drive the plunger.

[0009] Therefore, there is an unmet need for alternative injection devices for delivering a predetermined fixed dose that address the need for a simple, safe, user-friendly and robust medication delivery device.

[0010] In view of the above, it is an object of the present invention to provide a user-friendly, safe and robust drug delivery device for delivering a fixed dose of medicament.A further object is to provide such a drug delivery device comprising a drive mechanism having a helical and axial guide portion. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] International Publication No. 2020 / 089167 [Patent Document 2] International Publication No. 2019 / 09179 [Patent Document 3] International Publication No. 2017 / 106221 [Patent Document 4] International Publication No. 2018 / 007259 [Patent Document 5] International Publication No. 2017 / 098460 [Patent Document 6] International Publication No. 94 / 26331 [Patent Document 7] International Publication No. 2013 / 034651 [Patent Document 8] International Publication No. 2013 / 034647 [Patent Document 9] International Publication No. 2011 / 111006 Summary of the Invention

[0012] In the present disclosure, embodiments and aspects are described that address one or more of the above objects or that address objects apparent from the following disclosure as well as the description of the exemplary embodiments.

[0013] In a first aspect of the present disclosure there is provided a drug delivery device for delivering a fixed dose, the drug delivery device comprising: a housing assembly; a drug reservoir having a piston; a drive mechanism comprising: a piston rod operatively disposed within the housing assembly and adapted to advance the piston to expel medicament during dosing; and a drive tube operatively disposed with the piston rod (109, 209), the drive tube (180, 280) being axially movable relative to the housing assembly and adapted to be rotationally blocked in a stationary state and adapted to be axially movable and rotatable relative to the housing in a dosing state, the drive mechanism being adapted to deliver a predetermined fixed dose in response to actuation; an actuation mechanism for actuating the drive mechanism in response to axially moving the drive-tube; the housing assembly comprises a guide structure for guiding the drive tube during activation and delivery of the dose, the guide structure comprising an axial portion providing a sliding surface for guiding the drive tube during activation and for providing a rotational stop that defines an end position of the dose, and a circumferential portion providing a sliding surface adapted to guide the drive tube during administration; a guide structure, the drive tube comprising an axial portion adapted to slidably engage a corresponding axial portion of the housing assembly for actuation, and a circumferential portion for slidably engaging a corresponding circumferential portion of the housing assembly during dispensing; This allows the drive tube (180, 280) to be guided along the axial portion (156, 256) without rotation, thereby allowing it to be changed from a stationary state to a dosing state during activation, and this allows the drive tube (180, 280) to be moved axially and rotated by the drive mechanism in the dosing state, thereby allowing the drive tube (180, 280) to be guided along the circumferential portion (189, 289) to the end position of the dose, thereby allowing it to be changed from a dosing state to a stationary state in response to activation of the drive mechanism.

[0014] Thereby a drug delivery device is provided, where the drive mechanism comprises a helix and an axial guide portion which provides a fixed dose upon actuation.

[0015] In a further aspect, the guide structure of the housing assembly is a closed guide that provides an actuation cycle for the drive-tube, and the start position and end dose position of the drive-tube are the same.

[0016] Thereby, the drive mechanism is adapted to provide multiple fixed doses using the same actuation cycle.

[0017] In a further aspect, the circumferential portion (157, 257) of the structure of the housing assembly is a helical portion (157, 257) or a stepped portion having at least one step, and the corresponding circumferential portion (189, 289) of the guide portion of the drive-tube (180, 280) is a helical portion (189, 289) that corresponds to the helical portion (157, 257) of the housing assembly, or a stepped portion having at least one step that corresponds to the stepped portion of the housing assembly.

[0018] In a further aspect, the housing assembly further comprises internal threads and the piston rod comprises external threads that engage the internal threads of the housing assembly.

[0019] The piston rod is thereby operably disposed within the housing via the threaded connection.

[0020] In a further aspect, the drive tube is axially splined to the piston rod, thereby allowing relative axial movement and preventing relative rotation, whereby the piston rod (109, 209) is advanced in response to rotation of the drive tube.

[0021] This allows the piston rod to be operatively disposed with the splined connection, which may include a keyed fit in a keyed manner.

[0022] In a further aspect, the drive mechanism further comprises a motor mechanism for imparting rotation of the drive tube to deliver the dose in response to actuation of the drive mechanism, the drive tube being axially splined to the piston rod such that the drive tube is axially movable and rotationally locked relative to the piston rod, and the drive mechanism further comprises a return mechanism for axially moving the drive tube thereby returning the drive tube after actuation.

[0023] In a further aspect, the trigger mechanism includes a movably disposed connector, the connector including an actuation tab, the actuation tab adapted to engage a surface portion of the drive tube in response to moving the connector axially, thereby operably connecting the connector to the drive mechanism and adapted to trigger the drive mechanism, the surface portion being oriented in a direction toward the actuation tab.

[0024] This allows the actuation tab to abut a surface portion of the drive-tube during actuation.

[0025] In a further aspect, the rest state includes the drive-tube can be disposed in a home position, the drive-tube can be disposed in a first axial position, the drive-tube is permitted to move in one axial direction and blocked by the housing in the other axial direction, and disposed in a first angular position, the drive-tube is rotationally blocked by the housing in one direction and constrained in the other rotational direction by the drive mechanism, the guide structure of the drive-tube abuts an axial portion of the housing assembly and a helical portion of the guide structure of the housing assembly, and the dispense state includes - a first dispensing position, in which the drive tube can be disposed in a second axial position and a first angular position, whereby the drive mechanism is activated; - a second dispensing position, in which the drive tube can be positioned at an axial position between the first and second axial positions, as well as at an angular position different from the first angular position, and in which the helical portion of the guide structure is slidably positioned along the helical portion of the guide structure of the housing, whereby a dose can be expelled.

[0026] In a further aspect, the connector is adapted to move the drive tube between a first axial position and a second axial position, whereby the position of the drive tube (180, 280) is changed from a home position to a first dosing position in response to moving the connector from the first axial position to the second axial position, and the drive mechanism is adapted to rotate the drive tube in response to actuation of the drive mechanism by setting the drive tube at the first dosing position, whereby the position of the drive tube is changed from the first dosing position to the second dosing position and to the home position.

[0027] In a further embodiment, the first and second positions of the connector are different from the first and second positions of the drive-tube.

[0028] In a further aspect, the axial distance between the first and second locations of the connector is greater than or equal to the axial distance between the first and second locations of the drive-tube.

[0029] In a further aspect, the motor mechanism includes a torsion drive spring for rotating the drive tube by unwinding, the drive spring is secured between the housing assembly and the drive tube, the drive spring is further compressible to move the drive tube axially during rotation, and the drive spring provides a return mechanism for returning the drive tube after actuation.

[0030] In a further aspect, the drive spring comprises a compressible section.

[0031] In a further aspect, the actuation tab of the connector includes a lateral surface portion and the engageable surface portion of the drive tube is lateral, whereby initiation of administration is provided by rotational movement induced by the torsional drive spring in response to actuation of the drive mechanism.

[0032] In a further aspect, the drug delivery device includes a spring base rotatably disposed relative to the housing assembly, and a one-way ratchet mechanism is provided between the rotatably disposed spring base and the housing assembly, whereby the spring can be tensioned by rotating the spring base.

[0033] In further or alternative aspects, the motor mechanism comprises a compressed drive spring, the actuation tab comprises a helical surface portion, the engageable surface portion of the drive tube for actuating the drive tube comprises a helical surface portion, the actuation tab is adapted to impart an initial rotation of the drive tube in the administration direction in response to engaging the tab and moving the drive tube between the distal and proximal positions against the biasing force of the compression spring, and the helical portion of the housing assembly and the compression spring are adapted to provide further rotation of the drive tube in response to the initial position whereby the complete fixed dose can be delivered.

[0034] In a further aspect, the piston rod includes an axially extending raceway and the drive tube includes an inward protrusion adapted to slidably engage the axial raceway, thereby rotationally locking the drive tube relative to the piston rod.

[0035] In a further embodiment, the axial portion and helical portion of the housing's guide structure are axial and helical surface portions, respectively, and the axial portion and helical portion of the drive-tube's guide structure are axial and helical surface portions, respectively.

[0036] In a further aspect, the movement of the connector from the first axial position to the second axial position is a pure axial movement.

[0037] In a further aspect, the first axial position is a distal position and the second axial position is a proximal position.

[0038] In a further aspect, the drug delivery device is an injection device.

[0039] In a further aspect, the medication delivery device further comprises a shield for operating the connector, the shield adapted to cover a portion of the needle cannula at a distal position and to expose the needle cannula at a proximal position, with the shield in the proximal position a needle can be inserted into the subject, and the shield adapted to move the connector between first and second axial positions in response to moving the shield from the distal to the proximal position, the first and second positions of the connector being the distal and proximal positions.

[0040] In further or alternative aspects, the piston rod is axially splined to the housing assembly whereby the piston rod is axially movable and rotationally locked relative to the housing assembly; the drive tube further comprises internal threads whereby the piston rod is operably disposed within the housing assembly; the piston rod further comprises external threads for threadably engaging the internal threads of the drive tube whereby the piston rod is operably disposed with the housing assembly and the drive tube; the piston rod is advanced during rotation of the drive tube; and the drive mechanism comprises a motor mechanism comprising a compression drive spring for axially moving the drive tube and the piston; the medication delivery device further comprising a connector having an angled actuation tab adapted to engage an angled surface of the drive tube and impart an initial rotation of the drive tube in the administration direction in response to engagement between the actuation tab and the drive tube against the biasing force of a compressed drive spring; The stationary state includes that the drive-tube can be disposed in a home position, the drive-tube can be disposed in a first axial position, the drive-tube is permitted to move in one axial direction and blocked by the housing in the other axial direction, and in a first angular position, the drive-tube is rotationally blocked by the housing in one direction and constrained in the other rotational direction by the drive mechanism, the guide structure of the drive-tube abuts an axial portion of the housing assembly and a helical portion of the guide structure of the housing assembly, The administration status is the drive tube is in a first dosing position, the drive tube being capable of being disposed in a second axial position and a first angular position, and an activation tab engages the drive tube against the biasing force of a compressed drive spring, thereby activating the drive mechanism; - a second dispensing position, in which the drive tube can be positioned at an axial position between the first and second axial positions, as well as at an angular position different from the first angular position, and in which the helical portion (189, 289) of the guide structure is slidably positioned at any position along the helical portion (157, 257) of the guide structure of the housing, whereby a dose can be expelled; the drive tube and the piston move together as the position of the drive tube changes from the home position to the first dispense position; the drive tube is rotatable relative to the piston rod in response to an angular position of the drive tube being changed from a first dispense position to a second dispense position, the change in angular position relative to the housing being induced by a helical guide surface of the housing and a compressed drive spring; At the same time, the drive tube is movable with the piston rod in response to the angular position of the drive tube being changed from the first dispense position to a home position, where a change in axial position relative to the housing is induced by a helical guide surface of the housing and a compressed drive spring; Thereby, the fixed dose has been delivered when the drive tube returns to a home position in response to actuation of the drive mechanism.

[0041] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Brief description of the drawings]

[0042] [Figure 1A] FIG. 1A shows an exploded view of an injection device according to a first embodiment of the present disclosure. [Figure 1B] FIG. 1B illustrates details of the cartridge holder of the embodiment shown in FIG. 1A. [Figure 1C]Figure 1C illustrates details of the shield-following and moving parts of the cleaning assembly of the embodiment shown in Figure 1A. Figure 1C illustrates the structure in both black and white and in grey scale of window W1, where the piston is separated from the chamber. [Fig. 1D-1F] Figures 1D-1F illustrate details of the shield-following portion, cannula, needle hub, and cartridge-engagement structure of the cleaning assembly of the embodiment shown in Figure 1A. In Figure 1F, window W2 illustrates the assembly in grayscale, and W3 illustrates a cross-section of the hub in grayscale to reveal the guides on the inner surface. [Figures 2A-2D] Figures 2A-2D illustrate further details of the cleaning assembly of the embodiment shown in Figure 1A. Figures 2B, 2C, and 2D illustrate the structure in both black and white and grayscale with windows W4, W5, and W6, respectively, to enhance assessability of the voids, angled surfaces, and separate parts. Window W6 is angled to show the slit in the hub. [Figure 3A-3F] 3A-3F illustrate details of the guide structure of the elongated housing structure of the embodiment shown in FIG. 1A. [Figure 4A-4B] 4A and 4B illustrate details of the zero adjustment nut of the embodiment shown in FIG. 1A. [Diagram 5] FIG. 5 illustrates further details of the zero adjustment mechanism provided on the elongated housing structure of the embodiment shown in FIG. 1A. [Figure 6] 6 illustrates a cross-sectional view of a proximal portion of the injection device of the embodiment of FIG. 1A. The illustrated injection device includes a piston washer. [Figure 7] FIG. 7 shows details of the piston rod of the embodiment shown in FIG. 1A. [Figure 8A-8B] 8A and 8B show details of the drive-tube of the embodiment shown in FIG. 1A. [Figure 9A-9B] 9A and 9B show details of the housing insert portion of the embodiment shown in FIG. 1A. [Figure 10A-10C]10A-10C show details of the elongated shield structure of the embodiment shown in FIG. 1A. [Figure 11A-11B] 11A and 11B show details of the connector of the embodiment shown in FIG. 1A. [Figure 12A-12B] 12A and 12B show cross-sectional views of the proximal end of an injection device from two different angles. The illustrated device is the same as the embodiment shown in FIG. 1A. [Figure 13A-13D] 13A-13D show details of the drive mechanism of the embodiment shown in FIG. 1A. [Figure 14A-14B] 14A and 14B show cross-sectional views of the entire injection device from two different angles. The illustrated device is the same as the embodiment shown in FIG. 1A. [Figure 15A-15B] Figures 15A and 15B illustrate user actions and states during operation of the injection device of Figure 1 A. Figure 15A illustrates an action to obtain a first fixed dose, and Figure 15B illustrates a subsequent dose. [Fig. 16A-16T] 16A-16T show the injection device of FIG. 1A in different states and intermediate positions, thereby providing detailed illustrations of the operation of the device. [Figure 17] FIG. 17 shows an exploded view of an injection device according to a second embodiment of the present disclosure. [Figure 18] FIG. 18 illustrates a detail of a cross-sectional view of the embodiment shown in FIG. [Figure 19] FIG. 19 illustrates details of the housing of the embodiment shown in FIG. [Figure 20] FIG. 20 illustrates details of the inner tubular portion of the housing of the embodiment shown in FIG. [Figure 21] FIG. 21 illustrates details of the relocking tube of the embodiment shown in FIG. [Figure 22] FIG. 22 illustrates details of the connector of the embodiment shown in FIG. [Figure 23A-23B] 23A and 23B illustrate details of the drive-tube of the embodiment shown in FIG. [Figure 24]FIG. 24 illustrates details of the elongated shield structure of the embodiment shown in FIG. [Figure 15A-15B] Figures 15A and 15B illustrate user actions and states during operation of the injection device of Figure 1 A. Figure 15A illustrates an action to obtain a first fixed dose, and Figure 15B illustrates a subsequent dose. [Fig. 25A-25G] 25A-25G show the injection device of FIG. 17 in different states and intermediate positions, thereby providing detailed illustrations of the operation of the device during the first dose. [Figure 26A-26B] 26A and 26B show the injection device of FIG. 17 in different states and intermediate positions during a subsequent dose.

[0043] In the figures, similar structures are primarily identified by similar reference numbers. The letter "a" following the reference number is used to indicate the distal end of the structure, and "b" following the number is used to indicate the proximal end. Reference numbers, including a first number followed by a "." and a second number, are used to indicate a functional or structural detail of the structure. In this manner, the first number indicates a primary (relatively large) structure, and the second number indicates a secondary (relatively small) structure or specific function. The letters c, d, and e following the reference number indicate features with rotational symmetry. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0044] When terms such as "top" and "bottom", "right" and "left", "horizontal" and "vertical", or similar relative expressions are used below, they only refer to the attached figures and not necessarily to the actual usage situation. The figures shown are schematic, and therefore the relative dimensions thereof as well as the configuration of different structures are intended to serve for illustrative purposes only. When the term member is used for a given component, it can be used to define a single component or a portion of a component having one or more functions.

[0045] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments.

[0046] It should also be understood that, although terms such as first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first subject may be referred to as a second subject, and similarly, a second subject may be referred to as a first subject, without departing from the scope of the present disclosure. A first subject and a second subject are both subjects, but are not the same subject. Furthermore, the terms "subject", "user", and "patient" are used interchangeably herein.

[0047] As used herein, the term "when" can be interpreted to mean "when" or "in the course of" or "upon determining" or "upon detecting," depending on the context. Similarly, the phrase "when determined" or "when [described condition or event] is detected" can be interpreted to mean "upon determining," or "upon determining," or "upon detecting [described condition or event]," depending on the context.

[0048] As used herein, the terms distal and proximal end are similar to terms from anatomy used to describe ends located away from or closest to the attachment point to the body. Thus, the distal end of an injection device is defined in the context of a user holding the device in an injection ready position, whereby the end having the injection needle is the distal end and the opposite end is the proximal end. Additionally, the distal and proximal ends of the individual components of the device are also defined in that context.

[0049] As used herein, trailing edge and leading edge are used to describe the edges of a structure that moves relative to another structure. The leading edge is the edge in the direction of movement and the trailing edge is the opposite. Thus, the leading edge and trailing edge are defined according to the direction of relative movement between the structures.

[0050] As used herein, rotational symmetry is a property of a structure when it looks the same or retains the same function after some rotation by partial turns. The degree of rotational symmetry of a structure is the number of distinct orientations that look the same for each rotation. Rotational symmetry of degree n, where n is 2 or more, is also called n-fold rotational symmetry or discrete rotational symmetry of degree n, where n is 2 or more, about a specific point (2D) or axis (3D), which means that a rotation by an angle of 360° / n does not change the object. The properties of a structure can relate to both the visible appearance and the functional capabilities of the structural features.

[0051] As used herein, the term clockwise direction is used to describe the direction in which the hands of a clock rotate when viewed from the front. Thus, clockwise rotation of an injection device is the clockwise rotation observed when viewing the device from the front of the distal end. Counterclockwise or anticlockwise rotation is defined as the opposite direction.

[0052] As used herein, the proximal face is the face of the device when viewed in a distal direction from the proximal end, and the distal face is the face of the device when viewed in a proximal direction from the distal end.

[0053] As used herein, the positive axial or longitudinal direction is defined from the proximal end to the distal end. The positive axial and distal directions are used interchangeably with the same meaning. Similarly, the definitions of the negative axial and proximal directions are used interchangeably with the same meaning. The central axis of the device is defined through the center of the injection device in the positive axial direction, also referred to as the longitudinal axis, with the same meaning.

[0054] As used herein, the positive radial direction is defined along a radial axis originating at the central axis and perpendicular to the central axis.

[0055] A positive circumferential or positive angular direction is defined relative to a point located a radial distance from the central axis, with the circumferential direction being counterclockwise and perpendicular to the axial and radial directions. Directions as used in this disclosure can be both positive and negative. For example, the term axial direction encompasses a positive axial direction from the proximal end to the distal end, and a negative axial direction in the opposite direction.

[0056] Both the radial and circumferential directions are referred to herein as lateral directions because they are orthogonal to the axial direction. The lateral plane is defined herein as the plane that spans two vectors, the radial and the circumferential, for a given coordinate along the axis and with the central axis as the normal vector.

[0057] As used herein, axial movement of a structure is used to describe movement, where the displacement vector of the structure has a component in the axial direction. Translational movement is used to describe uniform movement in the axial direction only. Pure, exact, or uniform axial movement is the same as translational motion, and these terms are used interchangeably.

[0058] Radial movement of a structure is used to describe movement, where the displacement vector of the structure has a component in the radial direction. Pure, strictly radial movement is used to describe uniform motion in only the radial direction. Thus, pure, strictly, and uniform radial movement are the same, and these terms are used interchangeably.

[0059] Circumferential, angular, or rotational movement of a structure is used to describe movement, where the displacement vector of the structure has a component in the circumferential direction. Pure, strictly circumferential movement is used to describe uniform motion in the circumferential direction only. Thus, pure, strictly, and uniform circumferential movement is the same as pure, strictly, and uniform angular or rotational movement, and these terms are used interchangeably. The definition of rotational movement for a structure also encompasses the special case where the structure includes a central axis that defines the axis of rotation. In this special case, all positions of the structure off the central axis undergo circumferential movement, while the displacement vector of positions on the central axis is zero. Hence, a structure that rotates around its own central axis and moves axially is said to perform rotational movement.

[0060] Helical motion of a structure is used to describe a combined axial and angular or rotational motion, where the displacement vector of the structure includes circumferential and axial components. The definition of helical motion for a structure also encompasses the special case where the structure includes a central axis that defines the axis of rotation. In this special case, all positions of the structure off the central axis undergo helical motion, but the displacement vectors of positions on the central axis include only axial components. Hence, a structure that rotates around its own central axis and moves axially is said to perform helical motion.

[0061] In this context, pure, exact, and uniform movement are abstract mathematical definitions, and these terms are used to describe an ideal or abstract movement of a device. Hence, structures within an actual device should not be expected to exhibit this ideal behavior, but rather, such structures should be expected to move in a pattern that approximates such ideal movement.

[0062] As used herein, a right-handed thread or helical portion is a thread or helical portion whose helix moves in a positive axial direction when the thread is turned clockwise. A right-handed thread is usually a default thread and is threaded in a positive axial direction by counterclockwise rotation, which is usually performed by the right hand. Similarly, a thread having a left-handed thread is threaded in a positive axial direction by clockwise rotation, and thus may be performed with the left hand, mirroring the movements of the right hand to operate a right-handed thread.

[0063] The embodiments of the present disclosure are described in detail in relation to an injection device adapted to provide multiple fixed doses. However, the injection device may also be adapted to provide only one predetermined fixed dose, the amount of drug being defined by a drive mechanism, including the number of rotations per dose and the pitch screw of the piston rod.

[0064] The embodiments of the present disclosure in which the injection device is adapted to provide a plurality of predetermined fixed doses are described in detail in relation to an injection device comprising a reusable integrated needle cannula with a washing chamber. However, in an alternative embodiment, a needle magazine as described in EP20157959.6, entitled an injection device with integrated needles and filed by Novo Nordisk, may be integrated in place of a single reusable needle.

[0065] First embodiment 1-16 illustrate a first embodiment of an injection device for delivering multiple fixed doses according to the present disclosure. FIG. 1A shows an exploded view of the injection device. FIGS. 1B-14 show further details of the individual structures and mechanisms. FIGS. 15A and 15B show a series of states during use of the injection device 100 in perspective views, thereby illustrating user actions from receiving the device, starting the device, and delivering multiple fixed doses. FIG. 16 illustrates in detail the interrelationship of the mechanical structures during operation. As used herein, states define a particular arrangement or configuration of the device, and states and operations provide a framework for describing the working principle of the device.

[0066] FIG. 1A shows the cap 105, the shield tip 119, the shield following portion 120.1 of the cleaning module 120 (see FIG. 2B), the needle hub 125 with the needle cannula 124, the housing insert portion 160, the tubular elongated needle shield structure 110, the cartridge holder 130, the cartridge 135, the tubular elongated housing structure 140, the connector 170, the shield return spring 107, the drive tube 180, the dose drive spring 108, the piston rod 109, and the spring base 165.

[0067] Housing Assembly The injection device includes a housing assembly, providing a rigid frame with guides and connectors for guiding and connecting other components of the device. The housing assembly includes a housing insert 160, a tubular elongated housing structure 140, a cartridge holder 130, and a spring base 165. After final assembly, these structures are fixedly connected and the housing assembly can provide a frame of reference for describing the relative movement and position of the other structures. The elongated housing structure 140 includes an internal thread for engaging with the external thread of the piston rod. The internal thread can be provided in the form of an integral nut member that is both rotationally and axially fixed to the housing structure 140. In one example, the nut member is an integral part of the housing structure 140. Alternatively, the nut member can be a separate part that is fixed to the housing during assembly of the injection device, for example by gluing or welding. The nut member is on an inner surface that includes an internal thread that engages with the external thread of the piston rod 109 to move the piston rod in a helical manner when the piston rod rotates relative to the housing structure. Alternatively, the internal thread is provided directly in the housing. The housing insert 160 includes a cap snap at the end of the track for bayonet coupling with a cap. The housing insert 160 further includes a proximal edge for guiding the shield. For further explanation, the housing assembly may be referred to as the housing for short, and the needle shield assembly may be referred to as the needle shield.

[0068] The injection device 100 comprises a drive mechanism and a trigger or activation mechanism. The drive mechanism comprises a piston rod 109, a drive spring 108, and a drive tube 180, the structures operatively disposed within the housing to eject a dose. The trigger mechanism comprises an elongated shield structure 110 and a connector 170, the structures operatively disposed within the housing to trigger the dose ejection mechanism.

[0069] Needle Shield Assembly The injection device further comprises a needle shield assembly comprising a shield tip 119 and an elongated shield structure 110. The elongated shield structure 110 comprises a window 111 for inspection of the medicament, the elongated shield being capable of being positioned in a first position where it overlaps the cartridge holder window 131 and in a second position where it does not overlap, with a solid portion of the elongated shield structure covering the window 131 in the second position.

[0070] Cartridge Holder The cartridge holder 130 is adapted to receive a cartridge 135. The cartridge holder includes a window 131 for inspecting the medicament in the cartridge 135. Figure 1B shows the cartridge holder 130 in profile with an axial rib 132 for axially guiding the needle hub, a flexible arm for engaging a neck portion 137 (Figure 1A) of the cartridge, and a proximally extending tab 130.1 for aligning and positioning the cartridge when inserted into the housing during assembly. A circumferentially extending flange 134 (Figure 1A) is provided on the inner surface of the distal end of the cartridge holder to provide a small axial clearance to the distal end surface of the cartridge after assembly and in the initial unpackaged state.

[0071] cartridge As further shown in Figure 1A, the elongated cartridge 135 comprises a distal end 135a sealed by a pierceable septum and an open proximal end 135 closed by a piston. The piston is not shown in Figure 1. The cartridge comprises a reservoir containing a plurality of fixed doses of medicament. At the distal end 135a a septum is provided which is capped by a cap. The cap and the main portion of the reservoir are separated by a neck portion 137.

[0072] Needle Assembly The injection device further comprises a needle assembly comprising a needle hub 125 and a reusable needle cannula 124. The cannula comprises a proximal end for piercing the pierceable septum and establishing fluid communication with the reservoir, and a distal end for insertion into the skin of a subject or user of the device.

[0073] Piston washer Although not shown in FIG. 1, the piston washer may be connected to the piston rod to provide a hold down for contacting the piston. Alternatively, a dose measuring module for measuring the relative rotation between the piston rod and the piston may be provided between the piston rod and the piston. Such a measuring module also provides a suitable hold down. Such a dose measuring module is described in WO2014 / 1128155, entitled "Dose capturing cartridge module for drug delivery device". Alternatively, the piston rod directly contacts the piston.

[0074] cap The cap 105 is adapted for releasable mounting to the housing insert 160. The cap comprises an inner surface with protrusions 105.2 (FIG. 16F) adapted to be guided by axial and circumferential cap mounting tracks 161, which will be described in detail below in the present application. The protrusions are further adapted to cooperate with snap locks 161.1, thereby releasably locking the cap 105 to the inner housing part 160. The cap is adapted to be mounted and dismounted by continuous axial and rotational movements, thereby providing a bayonet coupling together with the injection device. The inner surface of the cap 105 further comprises axially extending ribs 105.1 (FIG. 16A) protruding from the inner surface and adapted for the cap to transmit torque to the shield structure 110 through axially extending ribs 116 on the outer surface of the shield, as described below with reference to FIG. 16A.

[0075] Spring Base Spring base 165 is fixedly mounted at a proximal end to housing structure 140 and is adapted to receive and support compressible torsion drive spring 108 .

[0076] Drive spring The drive spring 108 is pre-tensioned or pre-wound and positioned between the spring base and the drive tube 180. The drive spring is further adapted to induce a torque on the drive tube, whereby the medication may be expelled. The drive spring comprises torsion sections 108.3, 108.4, with a relatively small spacing between the coils, and compressible section 108.4 adapted to transmit an axial force to the drive tube after compression and during ejection of the medication. The ability to drive the drive tube axially allows for the termination of the dose mechanism and allows for resetting of the drive tube.

[0077] Return spring Connector return spring 107 is positioned between spring base 165 and connector 170 and is adapted to bias the connector in a distal direction.

[0078] Washing Assembly Cleaning the needle between injections allows the same integrated needle to be used multiple times in a clean condition. Therefore, in an alternative embodiment of the present disclosure, the injection device comprises a cleaning assembly 120, as illustrated in FIG. 2B. The movable shield structure 110 is fixedly connected to the cleaning assembly 120 through a shield following portion 120.1, the principles of the cleaning module being disclosed in more detail in WO2019 / 101670. The cleaning assembly 120 comprises a cleaning agent that keeps the distal end of the needle cannula 124 clean between injections. The shield following portion 120.1 of the cleaning module is fixedly connected to the shield tip 119, which is again fixedly connected to the movably arranged elongated needle shield structure 110. The shield tip 119 may snap into the needle shield structure 110 via a resilient arm 119.1 that engages with the elongated shield structure 110, such that the washing chamber assembly 120 follows the axial and rotational movements of the movably arranged shield structure 110. The shield structure 110, which is connected to the washing assembly 120, is movably arranged relative to a needle cannula 124 that is fixed to the housing.

[0079] The cleaning assembly 120 preferably contains a chamber having a liquid agent, which in one example may be the same preservative contained in the liquid agent of the cartridge 135. In a preferred example, the cleaning agent is a pharmaceutical liquid agent containing the same preservative that is contained in the cartridge 135, which is loaded into the chamber of the cleaning module during start-up of the injection device. In an alternative embodiment, the cleaning agent is embedded within a porous plug. In a further alternative, the cleaning agent is embedded within the matrix of a solid plug.

[0080] The shield may be placed in different positions. The initial position is defined by an initial angular position and a corresponding initial axial position. The locked position is defined by a locked angular position and a corresponding locked axial position. The unlocked distal position is defined by an unlocked angular position and a corresponding distal unlocked axial position. The movable shield may be changed by a combination of rotation and proximal movement from the initial position to a locked position where the shield is axially locked. In both positions, the needle tip is covered by the shield and housed within the washing chamber assembly. In use, the shield may be further rotated and moved further proximally to the unlocked distal position, thereby exposing the tip. By moving the shield further proximally, the shield exposes a larger portion of the needle and an injection may be performed. After injection, the shield is returned to the locked position, thereby washing the needle tip.

[0081] If for any reason it is desirable to reuse the needle without cleaning it, the cleaning module may be omitted.

[0082] Returning to the illustrated embodiment 100, FIG. 1B illustrates a perspective view of the cartridge holder 130 having proximally extending tabs 130.1 for aligning and positioning the cartridge holder 130 relative to the housing 140 when inserted into the housing during assembly. FIG. 1C illustrates an exploded view of the cleaning module 120 comprising a shield following portion 120.1 and a movable portion 120.2 comprising a piston 122 and a piston rod 123 having a radially extending arm 123.1 for cooperating with the needle hub 125 and the shield following portion 120.1. The radially extending arm 123.1 comprises a chamber housing engagement surface 123.2 for engaging the cleaning chamber 120 and a hub engagement portion 123.3 for engaging the hub 125. The needle following portion 120.1 comprises a cleaning chamber housing 121 comprising a distal tubular portion, a central tubular portion, and a proximal tubular portion. The parts are integrally connected. A cap is provided on the distal end of the distal tubular part to cap the distal bulkhead onto the wash chamber housing. A shield tab 121.1 for fitting onto the shield tip 119 and a hub push tab 121.2 are provided on the outer surface of the central tubular part. Window W1 in FIG. 1C illustrates the same components in gray scale to better illustrate the inclined surfaces and void portions. As shown in FIG. 2B, the proximal end of the wash chamber housing 121 is provided with an inclined proximal surface guide 121.3 for guiding the piston rod 123 and piston 122 proximally in response to rotation. Window W3 in the figure supports understanding of the mechanism for guiding or pushing the piston rod proximally. The rotating piston rod 123 will provide a first well-defined axial movement by releasing the static friction, rotating it further and pushing it into the inclined surface 121.3 of the wash chamber. Shown on FIG. 2D is a cleaning agent reservoir 121.4 for surrounding the distal end of the needle cannula in a sterile condition prior to use and in a clean condition during use.

[0083] FIG. 1D shows in perspective view the relative positioning of the needle cannula 124, the movable part of the washing chamber 120.2 including the piston 122 and the piston rod 122, and the cartridge engagement structure including the hard part 126 and the soft inner plug (not shown in the figure). The soft inner plug may be made of rubber and may be adapted to surround the proximal end of the needle cannula in a sterile initial condition before use. The hard part 126 provides support for the soft inner plug and is adapted to move the cartridge proximally when the needle establishes a fluid connection with the drug in the reservoir and in response to moving the hub 125 proximally. The soft plug may be pierced by the proximal sharp end of the needle cannula. The hard part 126 includes a radially extending hub engagement tab 126.1 and a radially extending cartridge engagement tab 126.2. The rigid portion further comprises a distally extending blocking portion 126.3 for blocking further axial movement of the hub when the hub is in the proximal position. As seen in FIG. 2D, the blocking portion 126.3 is adapted to engage with a small recess or circumferential slit 125.7 in the hub after a small relative rotation. The rigid portion 126 comprises a proximal surface at a proximal end 126b that abuts a distal surface of the assembled cartridge. Hence, proximal movement of the rigid portion 126 of the cartridge engagement structure provides proximal movement of the cartridge.

[0084] 1E illustrates a perspective view of the needle hub 125. The hub 125 comprises a central circular disk portion 125.9 and a proximally extending skirt portion 125.11 extending from the disk portion. The skirt portion 125.11 is adapted to encircle the distal end of the cartridge 135 and the cartridge engagement structure comprising the rigid portion 126. The needle hub 125 further comprises an axially extending finger 125.1 extending proximally from the skirt portion 125.11 and adapted to cooperate with an axially extending rib 132 of the cartridge holder to permit relative axial movement and prevent relative rotational movement between the hub and the cartridge holder. From the distal surface of the central disc portion 125.9 extend two axial tube portions (angular sections, curved like a tube but not extending 360 degrees in the circumferential direction) or flanges 125.12 connecting the tubular portion 125.13 with the central portion 125.9. The tubular portions are adapted to surround the cleaning assembly 120. As best seen in FIG. 2D, an adhesive tower 125.10 for securing a needle cannula is provided centrally on the central disc portion 125.9. The hub 125 further comprises a track provided on the skirt portion 125.11 and adapted to guide the rotational movement of the cartridge-engaging structure. The track comprises a proximal axial portion 125.2 providing an initial position for the hub engagement tab 126.1 of the cartridge engagement structure, and a helical portion 125.3 for rotating the tab 126.1 and thereby the rigid portion 126 of the cartridge engagement structure in response to guided proximal movement of the needle hub 125. The track further comprises a distal axial portion 125.4 adapted to allow or guide the relative axial movement or tab 126.1 and thereby the rigid portion 126 of the cartridge engagement structure upon completion of rotation. A rib 128 is provided on the inner surface of the axially extending flange 125.12, which projects in a negative radial direction, i.e., towards the center of the hub 125. The rib 128 comprises an axially extending surface 128.1 that is flush with the edge of the flange 125.12. The axially extending surface 128.1 provides a rotational stop for engagement with the piston rod 123.At the distal end of the rib 128, a circumferentially extending surface 128.2 is further provided (see also window W3 in FIG. 1F and FIG. 2D). The circumferentially extending surface 128.2 provides an axial stop for engaging with the pressure tab 121.2 of the chamber housing.

[0085] FIG. 1F illustrates the assembly of the modules shown in FIG. 1D with the hub 125 shown in FIG. 1E in an initial state and in an unpackaged state before a fluid connection is established between the needle cannula and the reservoir of the cartridge 135. Note that an axial clearance is provided between the blocking portion 126.3 and the proximal surface of the central portion 125.9, which allows for relative axial movement between the hub 125 and the rigid portion 126 of the cartridge engagement structure abutting the cartridge 135. The clearance therefore allows the needle cannula to be inserted into the cartridge in response to the relative axial movement. Window W2 illustrates the entire assembly shown in black and white on a gray scale. Window W3 illustrates the inner surface of the needle hub 125 and the guide 128 having surfaces 128.1 and 128.2.

[0086] FIG. 2A illustrates a perspective view of the washing chamber housing 121 positioned in the needle hub 125 in an unpackaged state. The tubular portion 125.13 surrounds the proximal portion of the washing chamber housing, and the radially extending hub push tab 121.2 rests on the distal support surface 127 of the hub in a first angular position. As will be described in detail later in this application, upon initialization, the needle shield is adapted to be guided in a proximal helical movement. When the washing chamber housing is secured to the needle shield, the push tab 121.2 performs a proximal helical movement relative to the rotationally fixed needle hub in response to initialization. The needle hub is axially movable between a distal and a proximal position. When the needle hub is axially movably positioned on the cartridge holder 130, the push tab 121.2 of the chamber housing urges the needle hub from a distal to a proximal position in response to the needle shield moving from an initial to a locked position. Further, during the axial movement of the shield, the push tab 121.2 is also rotated together with the shield from the initial to the locked angular position. In the locked angular position, the push tab 121.2 is angularly aligned with the notch 125.5 of the tubular portion 125.13 of the needle hub and aligned with the axial stop surface 128.2. An axial clearance is provided between the push tab 125.2 and the axial stop surface 128.2. Between the initial and locked angular positions of the shield, the hub moves a proximal distance to connect the proximal end of the needle cannula 124 with the reservoir of the cartridge 135. The proximal movement of the hub further provides a rotation of the cartridge engagement structure, whereby the tab 126.2 having the cam surface is rotated and forced into the axial clearance between the distal surface of the distal end of the cartridge and the proximal surface of the circumferentially extending flange 134 (see FIG. 1A). This increases the axial clearance between the cartridge and the circumferential flange 134, urging the cartridge proximally relative to the cartridge and deflecting the neck engagement arm 133. In the locked position of the shield, which corresponds to the proximal position of the hub 125, contact is established between the blocking portion 126.3 of the cartridge engagement structure and the central hub portion 125.9. In this position, the wash chamber housing can move proximally until it abuts the stop surface 128.2.When the shield 120.1 and shield following portion 120.1 are in the locked position, the shield following portion is adapted to move in a further proximal helical movement together with the shield to a distal unlocked position. When the shield and shield following portion 120.1 are in the distal unlocked position, the shield and shield following portion may move further in a strictly proximal direction to deliver a dose through the needle.

[0087] FIG. 2B illustrates a perspective view of the wash chamber piston rod 123 disposed within the wash chamber housing 121. As illustrated, the inclined surface 121.3 on the proximal surface of the chamber housing 121 is axially aligned with the axially extending surface 123.2 of the piston rod. In this initial position, the piston rod surface 123.3 is disposed in abutment with the rotational stop 128.1 of the hub 125 and is therefore unable to move in a counterclockwise direction relative to the hub. A circumferential clearance is initially provided between the inclined surface 121.3 and the chamber housing engagement surface 123.2, and in response to proximal helical movement of the chamber housing, the inclined surface 121.3 and the engagement surface 123.2 will approach and engage each other to come into contact. Any static or adhesive friction between the plunger 122 and the chamber housing 123 is thereby overcome by the relative rotation. In response to further rotation of the shield to the locked position, the ramp surface induces a proximally directed force on the piston rod 123, causing the piston rod 123 and plunger to be withdrawn from the wash chamber housing.

[0088] When the plunger 136 in the cartridge 130 is positioned against the piston rod 109, proximal movement of the cartridge relative to the cartridge holder (which is part of the housing assembly) will induce overpressure in the cartridge. If the reservoir is in fluid contact with the needle cannula, liquid will flow into the wash chamber. The additional feature of withdrawing the plunger 122 from the wash chamber housing 121 is provided to overcome adhesion friction between the plunger and the chamber housing 121, but withdrawal will also add flow between the reservoir and the chamber housing 121 when a fluid connection is established.

[0089] Housing Structure 3A and 3B illustrate perspective views of features disposed on the inner surface of the tubular housing structure 140 in an axial cut of the housing. In FIG. 3B, the axial cut is provided in a plane including the central axis of the window 141, and in FIG. 3A, the cut is rotated 90 degrees around the central axis, whereby one of the windows 141c is visible behind the cut plane. As seen in FIGS. 3C-3F, the tubular housing structure 140 comprises an outer tubular portion 143 and an inner tubular portion 154. In the illustrated example, the inner tubular portion 154 is integrally connected to the outer tubular portion. The outer tubular portion comprises an outer surface having an outer diameter and an inner surface having an inner diameter. Similarly, the inner tubular portion comprises an outer surface having an outer diameter and an inner surface having an inner diameter.

[0090] In Fig. 3A and Fig. 3B, the inner tubular portion 154 has been removed to obtain a clear view of the structure between the outer tubular portion 143 and the inner tubular portion 154. The figure illustrates a distal guide structure of the housing 142 protruding from the inner surface. The distal guide structure 142 is adapted to guide the shield structure 110. The figure further illustrates a central guide structure of the housing 144c and a proximal guide structure of the housing 146c. A central guide structure 144d, positioned 180 degrees from 144c in rotational symmetry, is also shown on Fig. 3D. The central guide structure 144 also protrudes from the inner surface and provides an integral connection between the outer tubular portion 143 and the inner tubular portion 154. The central guide structure is further adapted to guide the connector 170 and the shield structure 110. The proximal guide structure 146c forms a recess in its surface and is adapted to guide the connector 170. Distal, central, and proximal guides 142c, 144c, and 146c all have corresponding guides positioned with rotational symmetry, not all of which are shown or indicated, however, for example, reference to distal guide 142 may refer to any of the rotationally symmetrically positioned distal guides, and in the illustrated example 142, may refer to either or both of distal guides 142c and 142d.

[0091] The distal guide 142 comprises a first axial portion 142.1, a first transverse portion 142.2, a second axial portion 142.3, a second transverse portion 142.4, and a third axial portion 142.5 that provides a rotational stop. The central guide comprises a proximal transverse portion 144.1, a first axial portion 144.2, a distal transverse portion 144.3, and a second axial portion 144.4. The proximal guide comprises a first axial portion 146.1, a first transverse portion 146.2, a second axial portion 146.3, a third axial portion 146.4, a ramp portion 146.5, and a flush portion 146.6. Collectively, the guide surfaces provide a closed track that allows for annular guiding of the connector. The surfaces of the lateral portions extend radially and circumferentially, the surfaces of the axial portions extend axially and radially, and the surface of the ramp portion 146.4 extends from the bottom of the recess to the surface of the flush portion 446.5, which extends axially and circumferentially and is flush with the inner surface.

[0092] FIG. 3C corresponds to the cut shown in FIG. 3A, with the inner tubular portion 154 remaining. Note that the central guide 144 is positioned in the annular space between the outer tubular portion 143 and the inner tubular portion 154. FIG. 3D illustrates a perspective view of the housing structure 140 with a tubular cut made. The tubular cut is made in a plane that includes the inner surface of the housing structure, and the cut removes the structure outside of that plane. Thereby, only the structure on the inner surface is visible. FIG. 3D shows an internal connecting structure 140.3 for connecting with the housing insert portion 160. The connecting structure 140.3 is adapted to angularly position the insert portion relative to the housing structure 140. FIG. 3D further shows a rib 140.1, which together with the radial surface of the guide 142 supports the radial center position of the shield structure 110. A proximally positioned rib 140.2 supports the radial position of the return spring 107. At the proximal end, proximal to the rib 140.2, a portion of the elongated housing structure 140 is shown. FIG. 3E corresponds to the cut shown in FIG. 3B, with the inner tubular portion 154 remaining as in FIG. 3C. FIG. 3F shows a perspective view in FIG. 3D, but the structure is seen from a different angle revealing details of the proximal guide 146c. The proximal guide 146c is seen as a peripheral edge of a recess, but the edge is positioned in a plane with the inner surface. As can be seen, the guides 142, 144, 146 are provided with a two-fold rotational symmetry. With respect to the proximal guide 146c, the other rotationally shifted guides are not visible due to the angle of the perspective view.

[0093] 3A-3F therefore collectively show technical details of the housing structure 140 according to the first embodiment. The distal guide 142 of the housing is adapted to rotate and axially guide the shield along connected guide surfaces comprising a first axial portion 142.1, a first transverse portion 142.2, a second axial portion 142.3 and a second transverse portion 142.4. The central guide is adapted to rotate and axially guide the connector and comprises a proximal transverse portion 144.1, a first axial portion 144.2, a distal transverse portion 144.3 and a second axial portion 144.4. As explained below, the first axial portion 144.2 of the central guide 144 further provides a rotation stop for the shield 110 during injection. The proximal guide is adapted to guide the connector through an axial and rotational actuation cycle and comprises a first axial portion 143.1 adapted to provide a rotational stop to guide proximal axial movement, a first transverse portion 146.2 to guide rotational counterclockwise movement, and a second axial portion 146.2 adapted to provide a rotational stop to guide distal axial movement together with a third axial portion 146.3. The proximal guide further comprises a ramp portion 146.5 and a flush portion to guide the connector back to the beginning of an actuation or administration cycle.

[0094] Zero point adjustment mechanism 4A and 4B show perspective views of a zero-point adjustment nut 106 according to an alternative embodiment of the present disclosure. As shown, the distal face is visible at the distal end 106a in FIG. 3A and the proximal face is visible at the proximal end 106b in FIG. 3B. The adjustment nut 106 comprises an inner thread 106.1 for engaging with the outer thread 109.1 of the piston rod 109 and an outer thread portion 106.2 for engaging with the inner thread 154.2 of the housing. The outer thread 106.2 is provided proximally on the nut 106 in the illustrated embodiment and is shown as two outer thread portions protruding from the outer surface. The outer thread 106.2 may be made of any number of outer thread portions. Alternatively, the threaded connection 106.2, 154.2 between the nut 106 and the housing may be replaced by a purely rotating guide.

[0095] Furthermore, ratchet arms 106.3 are provided on the outer surface of the adjustment nut 106. In an embodiment of the present disclosure, two ratchet arms 106.3c and 106.3d are positioned with two-fold rotational symmetry at the distal end 106a of the adjustment nut 106. Any suitable number of ratchet arms 106.3 may be provided. However, at least two ratchet arms with rotational symmetry are preferred to increase the rotational stability of the adjustment nut 106. The two-fold rotational symmetry means that a rotation through an angle of 180 degrees around the central axis of the nut 106 does not change the appearance of the nut 106.

[0096] FIG. 5 shows a perspective view of the elongated housing structure 140 cut in half, whereby the inner surface of the structure is visible. The elongated housing structure defines a distal end 140a and a proximal end 140b. As can also be seen in the figure, on the inner surface of the elongated housing structure 140, an inner tubular portion 154 adapted to support the adjustment nut 106 is provided. The inner tubular portion 154 is also illustrated as a half tube due to the cut. The illustrated embodiment comprises an axial tooth 154.3 adapted to engage with the ratchet arm 106.3 of the nut, allowing the adjustment nut 106 to rotate in only one direction. The allowed direction of rotation is clockwise, which means that the interface of the ratchet arm 106.3 and the tooth 154.3 prevents the counterclockwise rotation of the nut relative to the housing. The prevented or blocked direction of the adjustment nut 106 is the same direction as the direction of rotation of the piston rod as the piston rod advances distally during administration. In this way, the adjustment nut cannot be unintentionally displaced during administration.

[0097] In some embodiments, the inner tubular portion 154 further comprises an internal thread 154.2 oriented such that the adjustment nut 106 is helically threaded in the proximal direction when rotated in the permitted clockwise direction. The threaded connection 106.2, 154.2 between the nut and the housing thereby provides an additional gear mechanism between the rotation of the adjustment nut 106 and the axial displacement of the rotationally fixed piston rod 109, which may be useful, for example, to compensate for a relatively large pitch threaded connection between the adjustment nut 106 and the piston rod 109.

[0098] During assembly of the injection device, it is desirable to ensure that the distance or gap between the piston rod 109 and the piston 136 in the cartridge 135 is minimized. Minimizing the gap ensures that medicament is expelled from the reservoir in response to moving the piston rod 109 in a distal direction. When the washer 104 is attached to the piston rod 109 as disclosed in the preferred embodiment shown in FIG. 6, the objective is to minimize the gap between the distal surface of the washer 104 and the proximal surface of the piston 136 such that the washer 104 and the piston 136 abut against each other when the injection device is placed in a state allowing storage and when the device is ready to be delivered to an end user. In the following, elimination of the gap will be described with reference to the piston rod abutting the piston, but the same considerations apply when the gap between the piston and the washer is eliminated.

[0099] When the adjustment nut is rotated relative to the housing structure during final assembly, the piston rod 109 is spirally advanced in a distal direction until the piston rod 109 or washer 104 abuts the piston 136 inside the cartridge 135. In embodiments with a threaded connection 106.2, 154.2 between the nut and the housing, the advancement of the piston rod relative to the housing is compensated or opposed by proximal movement of the adjustment nut relative to the housing.

[0100] Rotation of the adjustment nut is preferably performed by using a special tool in the production line that is adapted to engage and impart rotation to the adjustment nut. In one preferred example, the piston rod 109 is positioned to engage with the adjustment nut to provide a subassembly that is then positioned within the inner tubular portion 154 of the housing. Thereafter, an electronic computerized instrument is used to detect the relative position of the piston 136 within the cartridge 135 used for that particular injection device. When the position of the piston 136 and the position of the piston rod 109 are obtained, the computer can determine the required angular displacement of the adjustment nut 106 positioned to position the piston rod in abutment with the piston 136 when the injection device is assembled.

[0101] During assembly, the position of the proximal end of the piston rod 104 is therefore adjusted by rotating the adjustment nut in a unidirectional interface with the inner tubular portion 154. What is important here is that the adjustment nut can be rotated in a direction that advances the piston rod 109 into contact with the piston 136.

[0102] After assembly, the piston rod 109 or washer 104 abuts against the piston 136 and prevents further clockwise rotation of the adjusting nut. Furthermore, in either assembled state, there is no external interface between the nut 106 and the external surroundings. Therefore, there is no possibility to contact the external surface with an external tool and apply an external torque to the nut.

[0103] A result of the above is that the adjustment nut 106 is self-locking with respect to the housing structure and does not need to be physically secured to the housing. As such, it is not necessary to weld or glue the nut member 11 to the housing.

[0104] Drive mechanism FIG. 6 shows a cross-sectional view of the proximal portion of the injection device after a zero-point adjustment between the piston 136 and the washer 104. The piston rod 109 is positioned in a proximal position indicating that the first dose has not been expelled. FIG. 7 shows a perspective view of the piston rod 109, illustrating in detail the external thread 109.1 and the axial track 109.2. FIGS. 8A and 8B illustrate the drive tube 180 in perspective views from different angles. The figures show a tab 183c protruding from the outer surface and providing a structure for cooperation with the connector 170 during actuation of the drive tube 180 and for relocking of the shield structure 110 after the dose has been expelled. The tab 183 comprises a distally oriented surface 183.1 (distal surface or distally oriented surface means that at least a component of the normal vector is oriented in the distal direction) and an axial portion 183.2 providing an angularly oriented surface for cooperation with the connector 170. The figure also shows a helical structure 184c that protrudes from the outer surface and is adapted to axially block the connector during administration in response to an uncompleted attempt to stop administration. Tab 183 is positioned proximal to a lateral opening provided in the helical structure 184. The figure further illustrates an axial surface 182c that cooperates with the housing during activation and is adapted to provide a rotational stop that defines the end of the dose. Features 182, 183 and 184 will be described in detail below in the application.

[0105] The drive tube 180 includes an inward protrusion 180.2 that protrudes from the inner surface and is adapted to engage with an axial track 109.2 of the piston rod 109. The piston rod 109 is adapted to be slidably disposed within the drive tube, thereby allowing relative axial displacement but preventing relative rotation. The drive tube 180 includes a ratchet arm 181c for engaging with the teeth 165.1 on the inside of the tubular spring base 165, thereby forming a one-way ratchet interface, whereby the drive tube 180 is rotatable only in one direction, which in the disclosed example is the counterclockwise direction for dispensing a dose. The ratchet arm 181c thus prevents clockwise rotation of the piston rod 109. In the illustrated example, the drive tube includes two ratchet arms 181c, 181d arranged with two-fold rotational symmetry. The ratchet arm 181 provides a dose click sound during ejection in response to the drive tube 180 and piston rod 135 rotating in a counterclockwise direction.

[0106] The engagement between the piston rod 109 and the drive tube 180 prevents relative rotation, therefore, when the adjustment nut 106 rotates clockwise during zero adjustment, the nut induces distal translation of the piston rod 109 because the drive tube is locked against clockwise rotation.

[0107] The torque-delivery drive spring 108 shown in Figure 1, in an embodiment according to the present disclosure, is disposed inside the drive tube 180 and is fixedly attached at each end to the drive tube and spring base 165. The distal end includes distal attachment means 108.1 fixedly attached to the drive tube 180 and proximal attachment means 108.2 fixedly attached to the spring base 165. The drive spring is wound or tensioned during assembly, thereby storing energy to rotate the drive tube with sufficient torque to thereby deliver multiple doses without further tension.

[0108] Incorporating a torsion spring into the drive mechanism offers several advantages. The inventors of the present invention recognized that for one embodiment configured with a compression spring, the compression spring advances into the cartridge as it releases energy. If the injection device were designed without allowing the compression spring to advance into the cartridge, the overall length of the device would increase. Therefore, in a limited length configuration, the diameter of the spring is limited by the diameter of the cartridge. The inventors of the present invention found that the torsion spring does not need to extend into the cartridge to limit the overall length of the device. Therefore, a torsion drive spring is not limited by the diameter of the cartridge or the piston rod, which is advantageous in limited length configurations.

[0109] The torsion drive spring according to an embodiment of the present disclosure is located proximal to the cartridge and on the outside of the piston rod 109. The torsion drive spring thereby allows the spring to encompass a larger volume, thereby increasing the mass, i.e., the amount of spring material (e.g., steel). In other words, the performance related to long-term storage and administration can be improved because the material or mass used can be increased. With increased mass, the internal stress of the spring can be reduced and / or the spring outer diameter can be flattened, thus minimizing the variation in administration time between the first and last administration of the device. The inventors of the present invention have also found that if the maximum internal stress of the spring is reduced, the stress induced in the plastic components supporting the spring is also reduced, which is necessary to enable long-term storage.

[0110] The present inventors have further found that in one embodiment where the torsion drive spring is disposed inside the drive tube, the drive tube can be adapted to provide dose clicks, allowing for an increase in the number of dose clicks by increasing the diameter, and therefore the number of dose clicks can be increased without extending the axial length of the device.

[0111] According to one embodiment of the present disclosure, the outer surface of the drive tube comprises a dose click providing structure adapted to provide a dose click, e.g., a ratchet arm that rides on teeth provided on a surrounding structure. Alternatively, the ratchet arm is provided on a surrounding structure and teeth on the drive tube. As the circumference of the outer surface of the drive tube 180 increases with the diameter of the drive tube, the number of dose clicks also increases. In the case of a rotary drive tube, the number of dose clicks is determined as the relationship between the circumference of the drive tube and the distance between the dose click providing structure, e.g., the distance between the teeth (number of dose clicks = 2 * pi * radius / distance between teeth). Hence, the number of dose clicks can be increased by increasing the radius, but without increasing the length of the spring and, thereby, the length of the device. In contrast, to increase the number of dose clicks of a piston driven by a compression spring disposed within the piston, the length of the compression spring must be increased. In the case of a compression spring, the number of dose clicks is determined by dividing the axial extension of the spring by the distance between the teeth (number of dose clicks = axial extension / distance between teeth).

[0112] Furthermore, the inventors of the present invention have discovered that the energy required to release the trigger mechanism, i.e., the actuation energy, is a function of the internal stress of the drive spring. Therefore, actuation of a dose engine enabled by a torsion drive spring requires less force than a similar design based on a compression spring.

[0113] Additionally, the inventors have found that embodiments with drive mechanisms based on torsion drive springs are easier to assemble than equivalent compression drive spring based embodiments: compared to compression springs, torsion springs are relatively short and therefore easier to handle.

[0114] The rotating drive tube is readily adapted to work with an electronic dose capture device, which registers the rotating structure during administration, as described in WO2019 / 110494, entitled "Drug delivery system with multipolar magnet and sensor system."

[0115] Housing insert 9A and 9B illustrate two different perspective views of the housing insert 160, which is fixedly attached to the distal end of the elongated housing structure 110 via alignment and snap structures 160c.3. The housing insert comprises a cap mounting track 161. As can be seen, the cap mounting track 161c comprises an axially extending track portion 161c.2 having a proximal and distal end, and a circumferentially extending track portion 161c.3 having a first end and a second end. At a first end of the circumferential track, a snap lock 161c.1 is positioned, and a second end is connected to a proximal end of the axially extending track 161c.2, whereby the track portion forms a track for a bayonet coupling to cooperate with an inner protrusion of the cap 105. At a second end of the track 161c, a rotation stop 161c.4 is also provided. The housing insert portion 160 further comprises an axially extending slit 163c on its inner surface for cooperating with an axially extending rib 116c on the outer surface of the shield, as will be described below (see FIG. 10A). The inner housing portion 160 further comprises a proximal guide 162 for guiding the shield 110. The illustrated proximal guide 162d extends in the circumferential direction, in a counterclockwise direction, the guide comprises a helical portion 162d.1, a lateral portion 162d.2 having zero pitch, and an axial portion 162d.3. Alternatively, a threaded connection may be used for the bayonet connection.

[0116] Long and narrow shield structure 10A and 10B show perspective views of a cylindrical elongated shield structure 110 disposed inside a tubular housing 140. In FIG. 10A, the distal face of the shield structure 110 can be seen, and in FIG. 10B, the proximal face can be seen. FIG. 10C shows a portion of the shield structure in a side perspective view. The elongated shield structure 110 comprises a tubular portion with an outer surface having an outer diameter and an inner surface having an inner diameter. An axially extending rib 116c is disposed at the distal end ant protruding from the outer surface. The rib is adapted to cooperate with an internal rib of the cap 105 and with a slit 163 on the inner surface of the housing insert portion 165.

[0117] The shield structure 110 further comprises a stepped helical guide 112 disposed on the outer surface and adapted to cooperate with the proximal guide 162 of the housing insert and the distal guide 142 of the housing. The stepped helical guide 112 is provided in an annular space between the outer surface of the tubular portion of the shield structure 110 and the inner surface of the outer tubular portion 143 of the housing. The stepped helical guide comprises a continuous protruding structure extending axially and circumferentially, comprising a proximal lateral protruding portion, a proximal left helical protruding portion, a central lateral protruding portion, a distal left helical protruding portion, and a distal lateral protruding portion. The continuous protruding structure comprises a plurality of axially and circumferentially oriented surface portions that provide a guide surface (circumferential surface or circumferentially oriented surface means that at least a component of the normal vector is oriented in the circumferential direction). The surface portions can be seen in FIG. 10 and are referred to by the following terms and reference numbers: a proximal axial guide portion 112.1, a first proximal lateral guide portion 112.2, a second proximal lateral guide portion 112.3, a first proximal helical guide portion 112.4, a second proximal helical guide portion 112.5, a first central lateral guide portion 112.6, a second central lateral guide portion 112.7, a first distal helical guide portion 112.8, a second distal helical guide portion 112.9, a first distal lateral guide portion 112.10, a second distal lateral guide portion 112.11, and a distal axial guide portion 112.12. In this manner, guide portions 112.2, 112.4, 112.6, 112.8, and 112.10 provide a distal surface of the stepped spiral guide 112, and guide portions 112.3, 112.5, 112.7, 112.9, and 112.11 provide a proximal surface.

[0118] The elongated shield structure 110 further comprises a proximal guide 114 positioned at a proximal end of the shield structure 110. In FIG. 10A the distal face is visible, and in FIG. 10B the proximal face is visible. The proximal guide 114 is adapted to cooperate with the connector 170 of the housing and the central guide 144. The proximal guide 114 extends axially and circumferentially and comprises a first left helical portion 114.1, a first right helical portion 114.2, a second right helical portion 114.3, a second left helical portion 114.4, a first axial portion 114.5, a first lateral portion 114.6, a second axial portion 114.7, a third axial portion 114.8, and a second lateral portion 114.9.

[0119] Guide portions 114.1-114.9 are all surface portions, with guide portions 114.1, 114.2, 114.3, 114.4, and 114.9 providing the proximal face of proximal guide 114 and surface portion 114.6 providing the distal face, i.e., visible from proximal and distal positions, respectively. Proximal face guide portions 114.1, 114.2, 114.3, and 114.4 are adapted to cooperate with the connector during actuation.

[0120] A guide portion 114.6 on the distal face of the proximal guide is adapted to cooperate with the connector during administration in response to premature release of pressure on the shield, which will be described in detail later in the application.

[0121] The third axial portion 114.8 is adapted to cooperate with the central guide 144 of the housing to provide a rotational stop to prevent further counterclockwise rotation of the shield relative to the housing and during administration. Similarly, the second transverse portion 114.9 provides an axial stop to cooperate with the central guide 144 to prevent further proximal movement of the shield during administration.

[0122] Proximal guide 114 includes a locking structure 115 that includes guide portions 114.4 and 114.5, and in the illustrated embodiment, locking structure 115 is part of a hook-like structure that is adapted to releasably lock to a corresponding hook-like structure of connector 170 during administration, as will be described in detail below.

[0123] The shield further comprises a click arm 113, with an axial surface portion 113.1 providing a rotational stop. In an initial state, the click arm is radially compressed by the inner surface of the housing insert portion 160.

[0124] connector 11A and 11B show perspective views of a connector 170 disposed inside the tubular housing 140 and between the elongated shield structure 110 and the drive tube. The connector 170 is adapted to establish a connection between the shield and the drive tube and to actuate the drive tube 180. The connector 170 is further operatively connected with an automatic relocking mechanism adapted to automatically relock the shield at the end of the dose. The connector 170 comprises a distal guide 172 adapted to cooperate with the proximal guide 114 of the shield. The distal guide 172 extends circumferentially and axially and comprises a left helical portion 172.1, a right helical portion 172.2, a first axial portion 172.3, a lateral portion 172.4, and a second axial portion 172.5.

[0125] Guide portions 172.1-114.5 are all surface portions, with guide portions 114.1 and 114.2 providing the distal face of distal guide 172 and surface portion 172.4 providing the proximal face. Distal face guide portions 172.1 and 172.2 are adapted to cooperate with the shield's proximal guide during actuation. Proximal face guide portion 172.4 is adapted to cooperate with the shield's proximal guide guide portion 114.6 during administration in response to premature release of pressure on the shield, which will be described in detail later in this application.

[0126] The return spring 107 biases the connector in a distal direction, and thus the left helical portion biases the connector in a clockwise direction and the shield in a counterclockwise direction in response to establishing engagement between the left helical portion 172.1 and the first left helical portion 114.1 of the shield's proximal guide or establishing engagement between the left helical portion 172.1 and the second left helical portion 114.1 of the shield's proximal guide.

[0127] The distal guide 172 includes a locking structure 171 including a left helical portion 172.1 and a first axial portion 172.3. The locking structure 171 is part of a hook-like structure adapted to releasably lock with a corresponding hook-like structure of the proximal guide 114 of the shield. In response to the second left helical portion 114.4 of the locking structure 115 of the shield being abutted with the left helical portion 172.1 of the locking structure 171 of the connector under axial compression from the return spring 107, a releasable lock between the hook-like structures is established. This biases the shield in a counterclockwise direction and biases the connector towards a counterclockwise direction such that an abutment is established between the first axial portion 172.3 of the connector and the first axial portion 114.5 of the shield. To release the lock, the friction established at the abutment between the two left-handed helical portions 114.4 and 172.1 must be overcome in response to counterclockwise rotation of the connector.

[0128] The connector 170 comprises a tubular portion 170.1 having a full 360 degree circumference and two axially extending tubular portions 170.2 formed by two cutouts in the tube, thereby providing only a fraction of the circumference. The connector 170 has an outer surface having an outer diameter and an inner surface having an inner diameter. As illustrated in Figs. 12A and 12B, which are cross-sectional views of the proximal end of the injection device, the outer surface of the connector is disposed in close proximity to the inner surface of the outer tubular portion 143 of the housing. The connector surrounds the inner tubular portion 154 of the housing and the drive tube 180. The inner diameter of the connector is larger than the outer diameter of the tubular portion of the shield structure 110, and therefore the guide portions 172.1-172.4 are provided with shoulders projecting in a negative radial direction to allow contact between the proximal guide 114 of the shield and the distal guide 172 of the connector.

[0129] The connector further includes a central guide 174 adapted to cooperate with the housing central guide 144, thereby controlling the position of the connector relative to the housing. The connector central guide extends axially and circumferentially and includes a first axial portion 174.1 providing rotational stops, a first lateral portion 174.2, a second axial portion 174.3, a left-handed helical portion 174.4, a third axial portion 174.5, a fourth axial portion 174.6, and a second lateral portion 174.7.

[0130] The connector's central guide 174 defines a blocking structure comprising a second lateral portion 174.7 adapted to prevent unintended axial movement of the connector and thereby unintended actuation of the drive-tube 180.

[0131] The central guide 174 further defines a seat or locking structure 173 having a first lateral portion 174.2 and a second axial portion 174.3, the locking structure adapted to provide a rotational lock to prevent rotation and distal movement of the connector in the initial position, in which the connector 170 is in its distal-most position.

[0132] Connector 170 further includes an actuation tab 178 disposed on the inner surface and extending radially from the inner surface in a negative radial direction. Actuation tab 178 includes a first lateral portion 178.1 providing a proximal contact surface adapted to actuate drive tube 180. Actuation tab further includes an axial portion 178.2 adapted to release the automatic relocking mechanism in response to a clockwise impact from drive tube 180, and a second lateral portion 178.3 providing a retention portion to prevent split doses in response to premature release of pressure against the shield.

[0133] The connector further comprises a proximal guide in the form of a click arm 176 adapted to cooperate with the proximal guide 146 of the housing. A circle around the click arms 176c and 176d arranged with two-fold symmetry in their relaxed state defines a diameter larger than the outer diameter of the connector and larger than the inner diameter of the housing. Thus, in response to placing the connector 170 inside the outer tubular portion 143 of the housing with the click arm 176 in contact with the inner surface, the click arm is deflected in a negative radial direction. In this position, the click arm 176 exerts a radial force radially on the inner surface of the housing. The click arm comprises a first axial portion 176.1 for cooperating with the axial guide portions 146.1 and 146.3 of the proximal guide of the housing, and an axially and circumferentially extending outer surface portion 176.2 adapted to cooperate with the axial portion 146.4, the ramp portion 146.5 and the flush portion 146.6.

[0134] Proximal Part of the Injection Device Returning to Figures 12A and 12B, Figures 12A and 12B illustrate cross sections of the proximal end of the device. Figure 12A illustrates a central cross section with windows 141 (although they are located on the distal portion of the device that are not visible in Figure 12). Figure 12B illustrates a central cross section rotated 90 degrees relative to Figure 12A. Drive-tube 180, as shown in Figure 12B, comprises four tubular portions: first tubular portion 185, second tubular portion 186, third tubular portion 187, and fourth tubular portion 188.

[0135] The first tubular portion 185 is also a distal tubular portion and is disposed inside the inner tubular portion 154 of the housing. The distal tubular portion comprises an outer tubular portion 185.1 in contact with the inner tubular portion 154. The outer tubular portion 185.1 further comprises an axial surface portion 182c connected to the second tubular portion 186 and adapted to define the end of the dose and to cooperate with the housing during activation. The outer tubular portion 185.1 further comprises a distal helical surface portion 189c adapted to cooperate with a proximal helical surface portion of the inner tubular portion 154 of the housing during administration (see also FIG. 8A). The distal tubular portion 185 further comprises an intermediate tubular portion 185.2 extending in the proximal direction. A proximal portion of the intermediate tubular portion 185.2 is surrounded by a second tubular portion 186, thereby defining an annular spring receiving space that provides a distal base for the drive spring 108. An outer surface of the proximal portion of the intermediate tubular portion 185.2 defines a spring snap 180.2 for axially engaging the drive spring 108 in response to axial insertion of the drive spring into the annular spring receiving space. The distal tubular portion 185 further comprises an inner tubular portion 185.3 extending distally from the intermediate tubular portion and comprising an inward protrusion 180.2 adapted to engage an axial track 109.2 of the piston rod 109.

[0136] The second tubular portion 186 comprises protruding helical structures 184c and 184d on the outer surface. The second tubular portion 186 further comprises an axial surface portion 182d arranged in two-fold rotational symmetry with the axial surface portion 182c and adapted to cooperate with the housing during activation and to define the end of the dose. The second tubular portion 186 further comprises a distal helical surface portion 189d arranged in two-fold rotational symmetry with the distal helical surface portion 189c and adapted to cooperate with the proximal helical surface portion 157d of the inner tubular portion 154 of the housing during administration (see also FIG. 8A, and FIG. 13A). The protruding helical structure 184 protrudes from the outer surface of the second tubular portion 186 and extends to the inner surface of the connector 170. The helical structure 184 is adapted to axially block the connector during administration in response to an incomplete release of pressure on the connector, whereby the helical structure 184 blocks axial movement of the activation tab 178 which protrudes inwardly from the inner surface of the connector 170.

[0137] The second tubular portion 186 and the third tubular portion 187 are surrounded by the return spring 107. Together with the inner tubular portion 165.2 of the spring base 165, the second and third tubular portions 186, 187 define an annular space that accommodates a portion of the drive spring 108. The fourth tubular portion 188 of the drive tube 180 is also the proximal tubular portion and includes a ratchet arm 181c for engaging the teeth 165.1 on the inside of the outer tubular portion 165.3 of the spring base.

[0138] Starting mechanism FIG 13A illustrates a perspective view of the housing inner tubular portion 154 and drive tube 180, with the distal tubular portion 185 inserted within the inner tubular portion 154 and therefore not visible in the view, where the drive tube 180 is in a home position. Before the first dose, the home position is also referred to as the start position. After the first dose, the home position is also referred to as the end of dose position. FIG 13B illustrates a cross section taken along line CC as indicated, viewed from the proximal end. FIG 13C illustrates cross section CC as viewed from the distal end.

[0139] FIG. 13A further illustrates an actuation tab 178 on the inner surface of connector 170 (only the tab, the rest of the connector is not shown in FIG. 13A). The connector with actuation tab 178 is positioned so that it contacts protruding tab 183, ready to impart proximal movement to the drive tube, thereby actuating the drive tube. Drive tube 180 is biased distally and counterclockwise by a drive spring. In FIG. 13A, the drive tube is illustrated in a rest position, with axial surface portion 182 abutting axial surface portion 156 of inner tubular portion 154 of the housing, thereby preventing counterclockwise rotation of drive tube 180. In the rest position, distal helical surface portion 182 also abuts proximal helical surface portion 157 of inner tubular portion 154 of the housing, thereby preventing distal movement of drive tube 180.

[0140] 13D illustrates in detail the proximal end of helical surface portion 157d.1, which defines the beginning of the helical dispensing actuation, and the distal end of helical surface portion 157d.2, which defines the end of the helical dispensing actuation. Similarly, distal helical surface portion 189d defines a leading point or edge 189d.1 and a trailing point or edge 189d.2. In response to moving the connector proximally, actuation tab 178 induces proximal movement of drive tube 180 when it is placed in abutment with protruding tab 183. This causes leading edge 189d.1 to move proximally along axial surface portion 182d until it passes the proximal end of the axial surface portion and reaches start point 157d.1 of the helical dispensing trajectory. Due to the counterclockwise bias of the drive tube 189, the drive tube 189 rotates in a counterclockwise direction and due to the distal bias, the leading edge 189d.1 is forced into contact with the helical dose trajectory of the inner tubular portion 154. The drive tube with the leading edge 189d.1 then travels along the helical dose trajectory in a distal helical motion until it reaches the end point 157d.2. It can be seen that a small depression is at the end point 157d.2 of the helical dose trajectory. However, the depression is smaller than the extension of the helical surface portion 189d and therefore will not affect the helical movement of the leading edge 189d.1. The same effect can be obtained by the angularly shifted surface portion 182c and the distal helical surface portion 189c.

[0141] Cross section of the injection device in the activated state Figures 14A and 14B illustrate cross sections of injection device 100. Figure 14A corresponds to Figure 12A and illustrates a central cross section with window 141. Figure 14B illustrates a central cross section of the device after a 90 degree rotation relative to the view of Figure 14A. Drive tube 180 comprises four tubular sections, as shown in Figure 12B.

[0142] 14 illustrates device 100 in an actuated state, where the shield is rotated to actuate the device. The shield has moved proximally in a helical motion along with needle assembly 120. The proximal movement of the shield induces proximal movement of needle hub 125, whereby needle 124 has established a fluid connection with a reservoir within cartridge 135. Cartridge 135 and plunger 136 have also been moved in a proximal direction, and due to abutment with washer 104, the plunger has been stopped from moving proximally, whereby the chamber of cleaning assembly 120 has been filled (washer 104 is shown in FIG. 6 but not in FIG. 14).

[0143] Device Operation Fig. 15 is used to explain the working principle of an embodiment of the present disclosure from a user's perspective, a more detailed explanation of the working principle will be explained below with reference to Fig. 16. Fig. 15A shows a user action of the injection device 100 to obtain a first dose, and Fig. 15B shows the action to obtain a subsequent dose, which can be any of the fixed doses in a sequence between the first and last dose of the multiple fixed doses. The injection device may be stored and delivered in a secondary packaging, and in the unpackaged state (A1), the injection device has been unpacked from the secondary packaging.

[0144] As illustrated in FIG. 15A, when a user wishes to obtain a first fixed dose, the injection device is unpacked and thereby provided in an unpackaged state (A1). The injection device is then activated by the user. Activation may be performed by gripping the main part 102 of the device with the right hand and the cap 105 with the left hand. The user then rotates the cap in a counterclockwise direction (for the illustrated example). This causes the cap to disengage the cap snap 161.1 of the housing assembly and engage with the needle shield, whereby the needle shield follows the rotation of the cap 105 until the cap 105 is rotated to the rotation stop 161.4. Due to the stepped spiral guide 112 of the shield and the proximal guide 162 of the housing assembly, the needle shield undergoes a combined proximal and rotational movement in response to the user rotating the cap. Furthermore, this initial rotation of the cap and the combined rotation and proximal movement of the needle shield causes the needle cannula 124 to pierce the septum of the cartridge 135, thereby establishing fluid communication with the drug reservoir within the cartridge 135. Furthermore, in this action, the cartridge 135 is displaced proximally and pressed against the piston rod 109 or piston washer 104. As the cannula establishes a fluid connection and as the piston is placed against the piston rod, the integrated needle is primed, as will be described in detail below. When the cap reaches the rotation stop, the injection device is positioned in the cap unlocked and in the starting state (B1), and the cap is unlocked and positioned to be removed. The starting state is also shown in cross section in FIG. 15.

[0145] In the following step, the user pulls on the cap 105 of the injection device, which places the injection device in an uncapped state (C1) and the shield is locked against axial translation.

[0146] The user then manually rotates the shield in a counterclockwise direction, which places the device in a shield unlocked state (D1), where the shield is placed in an unlocked position and can be pushed proximally into the housing. Due to the guide between the shield and the housing 112, 162, the shield undergoes a combined proximal and rotational movement when operated between the capped and shield unlocked states. During the needle shield rotational unlocking movement, the needle shield does not cover the cartridge inspection window 141 in the housing, whereby the medication in the cartridge can be inspected. In addition, the piston 136 is also visible at the inspection window 141, and the position of the piston 136 relative to the fixed dose graduations on the housing indicates the progression of the piston during use, thereby indicating the number of fixed doses remaining in the reservoir. In FIG. 15A, in the shield unlocked state (D1), the piston 136 is placed in an initial position, with four doses remaining in the reservoir. During proximal movement of the needle shield, the distal end of the needle tip protrudes through a septum at the distal end of the cleaning assembly 120, thereby relieving any excess pressure on the needle.

[0147] Thereafter, the user presses the needle shield against the injection site, which displaces the shield and connector 170 proximally against the force of the shield return spring 107. This inserts the needle into the patient's skin or subcutaneous layer. This action causes the axial movement of the shield to trigger the drive mechanism and a fixed dose is delivered through the needle cannula in the dosed state (E1). At the end of the dose, the piston 136 has moved to the next position indicated by the fixed dose remaining scale on the housing, and the injection device can be removed from the injection site. A cutout window in the remaining scale indicates the piston in the next position. As the piston 136 progresses under the dosed state, it may be useful to define metastable states for each dosed state, i.e., an initial dosed state (E2.1) and a final dosed state (E2.2), where the piston is in a pressurized proximal position and a relaxed distal position, respectively.

[0148] After the dose is completed, the user removes the device from the skin, which releases pressure from the shield. As a result, the shield moves distally due to the action of the return spring 107. Due to the guides 112, 162 between the shield and the housing, and the guides 114, 142 between the shield and the connector 170, the shield undergoes a distal movement and then a combined distal and rotational movement, which causes the shield to automatically return to the relocked state (F1).

[0149] The user then applies the cap 105 by axial movement to place the device in the capped state (G1), which is the last state shown in the sequence shown in Figure 15 A. The cap-unlocked and capped states are technically different within the same sequence in that the cartridge contains fewer doses in the capped state.

[0150] Finally, the cap is turned, thereby snap-locking into the housing assembly, into the cap-locked state (A2) illustrated in FIG. 15B.

[0151] The cap-locked state (A2) differs from the out-of-box state (A1) in that the device has been triggered. This is illustrated in FIG. 15A and FIG. 15B as the shield in state (A2) is shifted proximally and rotationally compared to the position of the shield in state (A1). Furthermore, in state (A2), the cartridge contains fewer doses than in state (A1). When the user turns the cap to obtain a subsequent dose, the cap is turned to the cap-unlocked position without rotating the shield, since the shield has already been turned to the triggered but axially locked position. The cap-unlocked state (B2) differs from the cap-unlocked state (B1) in that in state (B2), the cartridge contains fewer doses than in state (B1), and corresponding differences can be observed between C1-C2, D1-D2...G1-G2, A2-A3, B2-B3..., etc. This pattern of movement can continue until the final dose is delivered and it becomes impossible to trigger the drive mechanism again.

[0152] Detailed description of the operation of the device Figures 16A-16T collectively illustrate the relative and functional arrangement of different structures during a series of states of the injection device 100, thereby illustrating the operation of the device in detail.

[0153] In one embodiment of the present disclosure, an injection device 100 for sequentially delivering multiple fixed doses comprises a housing with an elongated housing structure 140, a cartridge holder 130, and a housing insert 160, a shield with an internal thread, an elongated shield structure 110 and a needle tip 119, a needle hub 125 with a fixedly attached needle cannula 104, a cap 105 adapted to be removably mounted on the housing and cover a distal end of the shield, a cartridge 135 having a movably disposed cartridge plunger 136, and a drive mechanism comprising a torsion drive spring 108, a drive tube 180, and a piston rod 109 having an external thread for cooperating with the internal thread of the housing, the piston rod being disposed in connection with the plunger 136, and the torsion spring adapted to provide a torque for rotating the drive tube 180 relative to the housing. The drive tube comprises a ratchet mechanism that ensures rotation in the administration direction and prevents rotation in the non-administration direction. The drive tube is axially splined with the piston rod, thereby allowing relative axial movement and preventing relative rotation. The drive tube is adapted to advance the piston rod in response to rotating the drive tube in a dispensing direction, and due to the threaded connection with the housing, the piston rod is adapted to advance the plunger 136 in the cartridge 135 to eject the fixed dose. The drive mechanism is adapted to be activated by changing the drive tube from a distal position, where the drive mechanism is in a stationary mode, to a proximal position, where the drive mechanism is in a dispensing mode. In the distal position, the drive tube is rotationally locked to the housing. In the proximal position, the drive tube is rotationally unlocked from the housing, and the torque provided may rotate the drive tube through a predetermined angle to eject the fixed dose. In the stationary mode of the drive mechanism, the piston rod is rotationally and axially locked, where the piston rod is rotationally locked to the housing through the splined connection with the drive tube 180 and axially locked through the threaded connection with the housing.

[0154] The torsion spring is pre-tensioned to deliver multiple doses without binding during use. The drive mechanism is adapted to change modes upon activation, and as described below, the drive mechanism is adapted to be repeatably activated until the last dose is expelled.

[0155] The cap may be disposed in an axially locked position and an axially unlocked position. The cap may be repositioned by rotating the cap relative to the housing. When the cap is in the axially unlocked position, the cap may be removed from the housing.

[0156] The needle hub 125 is movably disposed on the housing and may be moved between a distal position and a proximal position relative to the housing. The needle hub 125 is disposed in connection with the cartridge and rotationally locked relative to the housing. When the needle hub is in the distal position, the proximal end of the needle cannula is disposed distally relative to the puncturable septum of the cartridge. With the needle hub 125 in the proximal position, the needle cannula extends through the septum and is positioned in fluid communication with the reservoir of the cartridge. In response to moving the needle hub from the distal to the proximal position, the needle cannula punctures the septum of the cartridge and moves the cartridge a proximal distance relative to the housing and the axially locked piston rod.

[0157] The shield may be disposed in different positions. The initial position is defined by an initial angular position and a corresponding initial axial position. The locked position is defined by a locked angular position and a corresponding locked axial position. The unlocked distal position is defined by an unlocked angular position and a corresponding distal unlocked axial position. The unlocked proximal position is defined by an unlocked angular position and a corresponding proximal unlocked axial position. In the initial position, the shield is adapted to prevent axial and clockwise movement and adapted to allow counterclockwise movement. In the locked position, the shield is adapted to prevent clockwise and axial movement. In this position, the shield is further adapted to allow counterclockwise rotation. In the unlocked distal position, the shield is adapted to prevent counterclockwise and distal movement of the shield and further adapted to allow proximal movement. In the unlocked distal position, the shield is further adapted to allow clockwise rotation if the applied torque exceeds a predetermined threshold. When the shield is in the initial and locked positions, the needle tip is covered by the shield. In the unlocked position, the shield is adapted to be moved proximally from the unlocked distal position, where the needle tip is not covered by the shield and pressure in the reservoir may be released, to the unlocked proximal position, where the needle tip extends further from the shield and may be inserted into the subcutaneous layer of the subject. The shield may be manually operated between different positions by a user. As viewed with respect to the shield in the initial position, the locked position, the distal unlocked position, and the proximal unlocked position, a set of four different angles and axial positions is defined, i.e., three different angles and four different axial positions.

[0158] The connector can be placed in an initial position defined by an initial angle and an initial axial position, which is rotationally locked and positioned in a central guide 144 of the housing, which also prevents distal movement of the connector. The connector is biased in the distal direction by a return spring 107.

[0159] 16A-16T collectively illustrate the injection device 100 positioned in different states and intermediate configurations, with the outer portion of the housing and the outer portion of the cap cut away to illustrate a portion of the internal structure.

[0160] FIG 16A illustrates the injection device in an unpackaged state, showing the cap 105, shield structure 110, housing insert 160, cartridge holder 130, connector 170, drive tube 180, and return spring 107, as well as the spring base 165. In FIG 16A, reference numbers are also provided for the proximal guide 162 of the housing insert, the stepped spiral guide 112 of the shield, and the distal guide 142 of the housing. The user receives the device from the pharmacy and unpacks the device from the secondary packaging. By unpacking, the user has provided the injection device in an unpackaged state.

[0161] Figures 16B-16E collectively illustrate intermediate positions between the unwrapped illustrated in Figure 16A and the cap unlocked state illustrated in Figure 16F. In Figure 16B, reference numbers are shown for details of the proximal guide 162 and the distal guide 142, in particular the helical portion 162.1, the lateral portion 162.2, the axial portion 162.3, the first axial portion 142.1, the first lateral portion 142.2, the second axial portion 142.3, and the second lateral portion 142.4. Reference numbers are shown for details of the stepped helical guide 112 in Figures 16C and 16E. In particular, the proximal axial guide portion 112.1, the first proximal lateral guide portion 112.2, the second proximal lateral guide portion 112.3, the first proximal helical guide portion 112.4, the second proximal helical guide portion 112.5, the first central lateral guide portion 112.6, the second central lateral guide portion 112.7, the first distal helical guide portion 112.8, the second distal helical guide portion 112.9, the first distal lateral guide portion 112.10, the second distal lateral guide portion 112.11, and the distal axial guide portion 112.12. Reference numerals for details of the proximal guide 114 of the shield are shown in FIG. 16DC. In particular, the first left helical portion 114.1, the first right helical portion 114.2, and the second right helical portion 114.3. Reference numbers for details of the connector's distal guide 172 are shown in Figure 16C, in particular the left helical portion 172.1, the right helical portion 172.2 and the first axial portion 172.3.

[0162] Unpackaged state The first user action is to rotate the cap counterclockwise until it reaches the cap axial unlocked position, which causes the shield to change from the initial position to a locked position, which causes the device to change from an unpacked state, through several intermediate positions, to a cap unlocked state, also called a shield actuation state.

[0163] More specifically, Fig. 16A illustrates the arrangement of the injection device as provided in an unpackaged state. The cap 105 is placed in an axially locked position and the shield is placed in an initial position. A small circumferential clearance is provided between the axially extending rib 116 projecting from the inner surface of the cap and the axially extending rib 105.1 projecting from the outer surface of the shield. The protrusions on the inner surface of the cap 105.2 are releasably retained in the cap mounting track 161 by snap locks 161.1.

[0164] FIG. 16B illustrates a first intermediate configuration of the injection device. Circumferential clearance has been eliminated by rotation, and abutment is provided between the axially extending rib 116 of the cap and the axially extending rib 105.1 of the shield. Further rotation will transmit torque from the cap to the shield. In the first intermediate configuration, circumferential clearance is provided between the first proximal helical guide 112.4 of the shield and the helical portion 162.1 of the housing insert, allowing relative counterclockwise rotation between the shield and the housing. Furthermore, only a small axial clearance is provided between the first proximal lateral guide portion 112.2 of the shield and the lateral portion 162.2 of the housing, preventing distal movement of the shield beyond the axial clearance. Similarly, only a small axial clearance is provided between the second proximal lateral guide portion 112.3 of the shield and the first lateral portion 142.2 of the housing, preventing proximal movement beyond the axial clearance.

[0165] In the second intermediate position of the injection device illustrated in Fig. 16C, the circumferential clearance between the stepped spiral guide 112 of the housing and the proximal guide 162 is eliminated to provide an abutment between the first proximal spiral guide 112.4 of the shield and the spiral portion 162.1 of the housing. In this position, a circumferential clearance is further provided between the second proximal lateral guide portion 112.3 of the shield and the first lateral portion 142.2 of the housing, whereby the lateral portion 142.2 does not impede axial movement.

[0166] In the third intermediate position of the injection device illustrated in FIG. 16D, the shield has been further rotated. In response to the rotation, the abutment between the helical guide portion of the shield and the housing provides a combined rotational and proximal movement relative to the housing. Thus, the stepped helical guide 112 has been moved proximally along the helical guide portion 162.1. The stepped helical guide portion comprises a leading edge and a trailing edge defined according to the direction of the relative movement between the shield and the housing. Due to the relative movement, the area of ​​abutment becomes progressively smaller until the trailing edge of the first proximal helical guide portion 112.4 reaches the proximal edge of the helical portion 162.1. In this position of minimum abutment, the abutment between the stepped helical guide and the housing is shifted from an abutment between the helical portions to an abutment between the lateral portions, whereby in response to a further counterclockwise rotation, the shield is guided in a pure rotation. In FIG. 16D, an abutment between the first proximal helical guide portion 112.4 of the shield and the helical portion 162.1 of the housing is provided between the distal portion (closer to the trailing edge) and the trailing edge of the first proximal helical guide portion 112.4. Furthermore, as illustrated in FIG. 16D, the connector is disposed in an initial angular and axial position, rotationally locked to the housing and prevented from distal movement, and the connector is biased in the distal direction by the return spring 107. Due to the proximal helical movement of the shield, a rest position abutment is established between the first left helical portion 114.1 of the proximal guide of the shield and the left helical portion 172.1 of the connector. In this position of the shield, a small axial clearance is provided between the second proximal helical guide portion 112.5 and the first lateral portion 142.2, thereby preventing pure axial movement in the proximal direction beyond the clearance.

[0167] In the fourth intermediate position of the injection device illustrated in FIG. 16E, the shield has been rotated further. The abutment between the lateral portion of the stepped spiral guide 112 and the housing provides a pure rotation. The stepped spiral guide 112 has therefore been moved in a counterclockwise direction along the lateral portion 162.2. The lateral guide portion 162.1 defines first and second edges, the second edge being in a counterclockwise position relative to the first edge. The first central lateral portion 112.6 comprises front and rear edges defined according to the direction of relative movement between the shield and the housing. Due to the relative movement, the area of ​​abutment becomes progressively smaller until the rear edge of the first central lateral guide portion 112.6 reaches the second edge of the spiral portion 162.2. In this position of minimum abutment, the abutment between the stepped helical guide and the housing is shifted from an abutment between the lateral portions to an abutment between the helical portions, thereby guiding the shield in a helical movement in response to further counterclockwise rotation. In FIG. 16E, an abutment is provided between the first central lateral guide portion 112.6 of the shield and the lateral portion 162.2 of the housing, between the center and rear edges of the guide portions. In the illustrated arrangement, a small axial clearance is provided between the second central lateral guide portion 112.7 and the first lateral portion 142.2 of the housing, thereby limiting proximal movement.

[0168] Cap unlocked, shield activated and locked In the cap unlocked and shield locked condition, as illustrated in FIG. 16F, the cap 105 is placed in an axial unlocked position and the shield is placed in a locked position. The cap is positioned with a protrusion 105.2 on the inner surface of the cap at the second end of the circumferential track portion 161.3, whereby the protrusion 105.1 is angularly aligned with the axial track portion 161.2 and can be moved distally. The shield is placed in a locked position and an abutment is established between the stepped helical guide 112 and both the lateral portion 162.2 and the helical portion 162.1. In addition to the abutment between the first left helical portion 114.1 of the proximal guide of the shield and the first left helical portion 172.1 of the connector, an additional abutment is provided between the first right helical portion 114.2 and the right helical portion 172.2. Due to the proximal movement of the shield, the connector has been moved proximally relative to the initial axial position and against the biasing force of the spring 107. The connector is still rotationally locked. To prevent clockwise rotation towards the unwrapped state, the axial surface portion 113.1 of the click arm abuts the axial portion 162.3 of the housing. The click 113 has been radially deflected from the compressed state behind the housing insert portion 162.

[0169] Cap removed A second user action is to pull the cap in a distal direction, which causes the device to change from the cap unlocked state to the cap removed state.

[0170] In the state illustrated in Fig. 16G, the cap has been removed from the main part 102 of the injection device shown in Fig. 16F. The position of the shield has not changed relative to the arrangement of Fig. 16F and is still in the locked position. The shield is axially locked but is allowed to perform a proximal helical movement guided by the abutment between the stepped helical guide 112 and the helical portion 162.1 of the housing.

[0171] Shield unlocked A third user action is to rotate the shield in a locked position in a counterclockwise direction until it reaches an unlocked position, thereby changing the device from an uncapped state through several intermediate positions to a shield unlocked state.

[0172] FIG. 16H illustrates a first intermediate position in which the shield is rotated. In response to the rotation, the abutment between the helical guide portion of the shield and the housing provides a combined rotational and proximal movement relative to the housing. Thus, the stepped helical guide 112 is moved proximally along the helical guide portion 162.1. The stepped helical guide portion comprises leading and trailing edges defined according to the direction of relative movement between the shield and the housing. Due to the relative movement, the area of ​​abutment becomes progressively smaller until the trailing edge of the first distal helical guide portion 112.8 reaches the proximal edge of the helical portion 162.1. In this position of minimum abutment, the abutment between the stepped helical guide and the housing is shifted from an abutment between the helical portions to an abutment between the lateral portions, whereby in response to further counterclockwise rotation, the shield is guided in a pure rotation. In FIG. 16H, the abutment between the first distal helical guide portion 112.8 of the shield and the helical portion 162.1 of the housing is provided between the proximal portion (close to the leading edge) and the trailing edge of the first distal helical guide portion 112.8. Furthermore, in the position of the shield illustrated in FIG. 16H, an abutment is established between the first left helical portion 114.1 of the proximal guide of the shield and the first left helical portion 172.1 of the connector. In this position of the shield, a small axial clearance is provided between the second proximal helical guide portion 112.5 and the first lateral portion 142.2, thereby preventing pure axial movement in the proximal direction beyond the clearance. Due to the proximal helical movement of the shield, the connector abutting the shield has been moved further in the proximal direction. Due to the rotational movement of the shield and the connector being rotationally locked by the housing's central guide 144, the shield 110 rotates relative to the connector 170, causing the right-handed helical portion 172.2 to slide along the first right-handed helical portion 114.2, thereby moving the first left-handed helical portion 172.1 out of abutment with the first left-handed helical portion 114.1 of the shield's proximal guide.

[0173] From the first intermediate position shown in FIG. 16H to the shield unlocked position shown in FIG. 16K1, the shield rotates in a proximal helical motion guided by the first distal helical portion 112.8, followed by a pure rotational motion guided by the first lateral portion 112.10. An arrangement for guiding the pure rotational motion is illustrated in FIG. 16J. The proximal rotational movement of the shield 110 relative to the housing 140 moves the shield 110 relative to the connector 170, which moves the connector relative to the housing. The right helical portion 172.2 slides from the first right helical portion 114.2 (FIG. 16H) along the second right helical portion until the trailing edge of the helical portion 172.2 reaches the proximal edge of the second right helical portion (FIG. 16J). Once the trailing edge has passed, a new abutment is established between the second left helical portion 114.4 and the left helical portion 172.1 of the connector as the locking structure 171 of the distal guide of the connector moves into engagement with the locking structure 115 of the proximal guide of the shield (FIG. 16K1). As the left helical portions 114.4, 172.1 of the locking structures 115, 171 abut under the biasing force of the return spring 107, the shield is biased in a counterclockwise direction, whereby the distal axial guide portion 112.12 contacts and is rotationally stopped by the third axial portion 142.5 of the housing. Due to the biasing force and the helical engagement, a releasable locking mechanism is provided. To release the lock, a torque exceeding the release threshold torque is required. As described above, the connector 170 is moving simultaneously relative to the housing. The connector 170 has been pushed out of its rotational engagement with the housing's central guide 144 (FIG. 16H). This has caused the trailing edge of the second axial guide portion 174.3 to pass the distal end of the intermediate guide's first axial portion 144.2, thereby shifting the first axial portion 144.2 from abutting with the second axial guide portion 174.3 to abutting with the left helical portion 174.4. The connector 170 is guided along the left helical portion 174.4 until the connector's click arm 176 abuts the housing's proximal guide's first axial portion 146.1, as shown in FIG. 16K1. FIG. 16K2 illustrates the relative orientation of the connector 170 to the drive tube 180 with the connector's angle portion removed.The remaining portion includes the actuation tab. The position of actuation tab 178 is indicated by lateral portion 178.1 and axial portion 178.2. As shown, lateral portion 178.1 abuts lateral portion 183.1 of protruding tab 183 of the drive tube. Connector 170 is thereby positioned to transmit force and proximal movement to the drive tube. FIGS. 16K3 and 16K4 show the arrangement of FIG. 16K2 from the opposite side (180 degree rotation about the central axial axis). As also shown in FIG. 16K3, upon placing the shield in the shield-locked state, the connector has translated the drive tube a small distance proximally relative to its initial position, thereby revealing proximal helical surface portion 157 (see FIG. 16K3). The initial position of drive tube 180 is shown in FIG. 13A. FIG. 16K4 illustrates the injection device in grayscale, which provides a better impression of the surface orientation and extension of different structures.

[0174] Administration status A fourth user action is to rotate the shield, which is in the unlocked distal position, proximally until it reaches the unlocked proximal position, thereby changing the device from the shield unlocked state through several intermediate positions to the administration state.

[0175] From the shield unlocked state shown in FIG. 16K1 to the first configuration of the injection device shown in FIG. 16L1, the shield is forced axially from an unlocked distal position to an unlocked proximal position, whereby the activation tab 178 is forced through a lateral opening in the outer helical structure 184. The proximal movement of the shield causes the shield to move the interlocked connector 170. The connector abutting the drive tube 180 moves the drive tube 180 from a distal rest position where the drive tube is rotationally locked by the housing to a proximal rotated position where the drive tube rotates relative to the housing. The proximal movement compresses the torsionally tensioned drive spring 109 into a compressed state. From the first configuration of the device in the dispense state (FIG. 16L1) to the last illustrated configuration in the dispense state (FIG. 16N1), the drive-tube has rotated 360 degrees, i.e., a full rotation, during distal helical movement back to the initial position in the housing (FIGS. 13A and 13N3) where it is rotationally locked to the housing, thereby expelling a fixed dose. The rotational movement of the drive-tube has caused the drive-tube with the leading edge of distal helical surface portion 189 to move counterclockwise along proximal helical surface portion 157 of inner tubular portion 154 of the housing from the starting dispense position illustrated in FIG. 16L3 to the mid-shield unlocked position illustrated in FIG. 16M3 and FIG. 16M4 where axial portion 183.2 abuts against axial portion 178.2 of tab 178, as shown in FIG. 16M2. The drive tube, having a leading edge of distal helical surface portion 189, continues its distal helical movement along surface portion 157 until it reaches axial surface portion 156 of inner housing tubular portion 154. The drive tube is rotated by torsionally pretensioned drive spring 108, and the helical surface portion of the drive tube remains in contact with the housing helical surface portion 157 as the compressed drive spring 108 unfolds during unwinding. This returns the drive tube to its initial position, which corresponds to the drive tube reaching a stop-dose position, and further counterclockwise rotation is prevented, as illustrated in Figures 13A and 13N3.In this position, actuation tab 178 can be moved proximally through a lateral opening in outer helical structure 184 in response to release of the axially and proximally directed force on the shield, i.e., release of pressure on shield tip 119 as the device is lifted from the skin. As viewed with the drive tube in the start dispense position, mid shield unlocked position, and stop dispense position, three different sets of angular and axial positions are defined, i.e., three different angular coordinates and three different axial coordinates.

[0176] Initializing the automatic relocking mechanism During rotation of the drive tube 189 from the mid-shield unlocked position to the stop-dose position, the drive tube provides a torque to the connector that exceeds the release threshold torque, causing the connector's locking structure 171 to disengage from the shield's locking structure 115 and the connector to rotate into abutment with a rotational stop provided within the housing. By disengaging the locking structures from one another, the automatic shield relocking mechanism is initiated.

[0177] During counterclockwise rotation, the trailing edge of the left helical portion 172.1 moves slightly proximally along the second left helical portion until the proximal edge of the second left helical portion 114.1 is surpassed. The connector thereby shifts from abutment with the left helical portion 114.4 of the shield to abutment with the right helical portion 114.3 of the shield, i.e., the abutment between the right helical portion 172.2 of the connector and the second right helical portion 114.3 of the shield is re-established. Due to the right helical abutment, the connector is biased counterclockwise under the distally directed biasing force of the return spring 107. However, during rotation of the connector, the connector arm 176 rotates along the first lateral portion 146.2 of the proximal guide of the housing and to an angular position of abutment between the axial surface 176.1 of the connector arm and the second axial portion 143.3 of the proximal guide of the housing. An optional and additional abutment is provided between the third axial portion 174.5 of the connector's central guide and the first axial portion 144.2 of the housing's central guide, which prevents further counterclockwise rotation of the connector 170. As the shield 110, in this unlocked proximal position, is prevented from clockwise rotation due to the abutment between the distal axial guide portion 112.12 of the shield's stepped helical guide and the second axial portion 142.3 of the housing's distal guide, and possibly due to the optional abutment between the third axial portion 114.8 of the shield's proximal guide and the second axial portion 144.4 of the housing's central guide, the connector may only move the shield axially with a pure axial movement.

[0178] Split dose prevention During actuation of the drive tube 180, the connector is moved in a pure proximal axial direction until the actuation tab 178 reaches the position shown by the patterned rectangle in FIG. 16L3. As described above, this movement of the connector results in the drive tube 180 being moved between a distal rest position where the drive tube is rotationally locked by the housing, to a proximal rotated position where the drive tube will rotate relative to the housing due to the torsion provided by the drive spring 108. This axial movement causes the actuation tab to be moved through a lateral opening in the helix 184, and as the drive tube reaches the proximal rotated position, it begins to rotate and an outer helix 184 protruding from the outer surface of the drive tube rotates into lateral overlap with the actuation tab 178, thereby holding the actuation tab and connector in a position proximal of the helix 184. During rotational movement of the connector from the start-dosing position seen in FIG. 16L3 to the stop-dosing position seen in FIG. 16N3, the activation tab 178 is retained on the proximal side of the helix 184 of the drive tube, thereby preventing a split dose. If pressure is released prematurely, i.e., before the stop-dosing position is reached, the connector and shield will be moved distally until axial abutment between the distally oriented retention portion 178.3 of the activation tab 178 and the helix 184. Thereafter, if the axial proximal force on the shield is not re-established, the activation tab will slide along the helix 184 as the drive tube rotates to the stop-dosing position, thereby causing the activation tab to be moved in a pure distal axial direction through a lateral opening in the helix 184.

[0179] Figures 16M1-16M3 illustrate the same configuration of injection device 100. Figure 16M2 illustrates the device from the same angle as Figure 16M1, but with the angled portion of the connector cut away. Figures 16M2 and 16M3 are views from opposite locations (rotated 180 degrees about the central axial axis). Figure 16M4 illustrates Figure 16M3 in grayscale.

[0180] Figures 16N1-16N3 illustrate the same configuration of injection device 100. Figure 16N2 illustrates the device from the same angle as Figure 16N1, but with the angled portion of the connector cut away. Figures 16N2 and 16N3 are views from opposite locations (rotated 180 degrees about the central axial axis).

[0181] Relocked state A fifth user action is to release the axially directed force on the shield by lifting the needle tip 119 from the skin, whereby the shield, which is in the unlocked proximal position, is moved distally until it reaches the locked position, thereby changing the device from the administered state, through several intermediate positions, to the relocked state.

[0182] From the final configuration in the dispensed state shown in FIG. 16N1 to the intermediate configuration shown in FIG. 16P, the shield 110 has been moved axially by the connector 170 from an unlocked proximal position to an unlocked distal position, whereby the activation tab 178 has been moved through a lateral opening in the outer helix 184. From the intermediate configuration shown in FIG. 16P to the intermediate configuration shown in FIG. 16Q, the connector rotates the shield in a clockwise direction. From the intermediate configuration shown in FIG. 16Q to the relocked state shown in FIG. 16S, the shield has been moved by the connector 170 in a distal direction during clockwise rotation.

[0183] During distal movement, the right-handed helical portion 172.2 of the connector abuts the second right-handed helical portion 114.2 of the shield. Due to the helical abutment between the connector and the shield, the shield is urged in a clockwise direction, thereby urging the distal axial portion 112.12 toward the second axial portion 142.3 of the housing. The shield is therefore guided axially along the distal guide of the housing until the trailing edge of the helical portion 172.2 reaches the distal edge of the second axial portion 142.2, thereby allowing the shield to rotate in a clockwise direction in response to further distal movement, as illustrated in the intermediate position shown in FIG. 16P. During clockwise rotation, illustrated by the intermediate configuration shown in Figures 16P-Q, the stepped helical guide 112 slides between the first lateral portion 142.2 and the lateral portion 162.2, while the connector urges the shield 110 to slide along the shield's proximal guide 114. When the trailing edge of the first distal lateral guide portion 112.10 reaches the edge between the lateral portion 162.2 and the helical portion 162.1 (Figure 16Q), the shield may move in a combined distal and rotational movement guided by the connector moving along the second right helical portion 114.3 to a rest position abutting the first left helical portion 114.1 of the proximal guide (Figure 16S).

[0184] During distal movement of the shield, the connector 170 moves in a distal direction guided by the first axial portion 144.2 of the housing's central guide, which prevents counterclockwise rotation, as illustrated in the final configuration of the administered state (FIG. 16N1) and the intermediate configurations of FIGS. 16P and 16Q. When the leading edge of the left helical portion 174.4 reaches the proximal edge of the first shaft portion 144.2, clockwise rotation of the connector is initiated. During distal movement, the connector arm or click arm 176 moves along the axial guide portions 146.3 and 146.4 and along the ramp portion 146.4 to the flush surface portion 146.5, whereby the click arm 176 is radially compressed, as shown in FIG. 16Q. As the connector 170 is moved further distally, the left helical portion 174.4 slides along the central guide 144 of the housing, inducing a clockwise rotation until the trailing edge of the helical portion 174.4 reaches the proximal edge of the first axial portion 144.2. In this position, the connector has nearly reached a rest position with the proximal guide of the shield, the left helical portion 172.1 abutting the first left helical portion 114.1, and the connector arm has returned to abutment with the first axial portion 146.1 of the proximal guide, as illustrated in FIG. 16R. The connector arm has thereby been reset to its initial position, ready to guide the connector during a new activation and administration cycle. From the intermediate position of FIG. 16R to the relocked position of FIG. 16S, the connector is moved distally into the seat where the first lateral portion 144.1 abuts the first axial portion 174.2 and the axial portions 144.1, 144.2, 174.1, and 174.3 prevent rotation.

[0185] With the cap on, with the cap locked The fifth user action is to put on the cap as illustrated in Fig. 16T, whereby the protrusion 105.2 is inserted into the axial track portion 161.2, whereby the cap can be rotated to place the device in the cap locked state shown in Fig. 15B (the cap locked state is not shown in connection with the detailed description of the actions). As seen in Fig. 16T, the axially extending rib is in a position to move away from the protrusion 116 when the cap is rotated to the locked position. Hence, there is no interaction between the cap 105 and the shield 110 when the cap is locked.

[0186] Second embodiment Figures 17-26 illustrate a second embodiment 200 of an injection device for delivering multiple fixed doses according to the present disclosure. Figure 17 shows an exploded view of the injection device, and Figure 18 shows a cross-sectional view. Figures 18-23 show further details of the individual structures and mechanisms. Figures 25 and 26 illustrate in detail the interrelationship of the mechanical structures during operation.

[0187] FIG. 17 shows the cap 205, the shield tip 219, the shield follower part 220.1 of the cleaning module, which also includes a movable part, corresponding to the movable part 120.2 of the first embodiment 1. FIG. 17 further shows the needle hub 225 with the needle cannula 224, the tubular elongated housing structure 240, and the housing cap part 260 connected at the distal end of the housing structure 240. The figure further shows the tubular elongated needle shield structure 210, the cartridge holder 230, the cartridge 235, the connector 270, the shield return spring 207, the drive tube 280, the dose drive spring 208, the piston rod 209, and the spring base 265. The figure further shows the piston washer 204 with a ratchet arm and an external thread for engaging the toothed ring and the internal thread on the inner surface of the piston rod 209, respectively, whereby a zero point adjustment for the piston in the cartridge 235 can be performed. 18 illustrates a cross-sectional view of the injection device 200, with the injection device in an unpackaged state. The cross-sectional plane cuts through the window 211 in the shield.

[0188] Housing Assembly The injection device includes a housing assembly, providing a rigid frame with guides and connectors for guiding and connecting other components of the device. The housing assembly includes a housing cap portion 260, a tubular elongated housing structure 240, a cartridge holder 230 with a window 231, and a spring base 265. After final assembly, these structures are fixedly connected and the housing assembly may provide a frame of reference for describing the relative movement and position of the other structures. The elongated housing structure 140 includes an internal thread 254.3 for engaging with the external thread of the piston rod.

[0189] The injection device 200 comprises a drive mechanism and a trigger or activation mechanism. The drive mechanism comprises a piston rod 209, a drive spring 208, and a drive tube 280, the structures operatively disposed within the housing to eject a dose. The trigger mechanism comprises an elongated shield structure 210 and a connector 280, the structures operatively disposed within the housing to trigger the dose ejection mechanism.

[0190] The tubular portion 254 comprises a central guide 244 comprising an outer axial portion 244.1 symmetrically disposed about the longitudinal axis at a first radial position and thereby defining a first diameter, and an inner axial portion 244.2 symmetrically disposed about the longitudinal axis at a second radial position and thereby defining a second diameter.

[0191] Needle Shield Assembly The injection device further comprises a needle shield assembly comprising a shield tip 219 and an elongated shield structure 210. The elongated shield structure 110 comprises a window 211 for inspection of the medication, the elongated shield being capable of being positioned in a first position where it overlaps the cartridge holder window 231 and in a second position where it does not overlap, with a solid portion of the elongated shield structure covering the window 231 in the second position.

[0192] Cartridges and Cartridge Holders The cartridge holder 230 is adapted to receive the cartridge 235. The cartridge holder includes a window 231 for inspecting the medication in the cartridge 235. The cartridge 135 and the cartridge holder 230 are structurally and functionally similar to the cartridge 135 and the cartridge holder 130 of the first embodiment, respectively.

[0193] Needle Assembly The needle assembly, including needle hub 225 and needle 224, is structurally and functionally similar to the needle assembly of the first embodiment.

[0194] cap The cap 205 is adapted for removable mounting to the housing cap portion 260. The cap includes an inner surface having protrusions adapted to mate with the bayonet coupling tracks. The inner surface of the cap 105 further includes axially extending ribs (not shown) protruding from the inner surface and adapted to transmit torque to the shield structure 110 through axially extending ribs 216 on the outer surface of the shield. The cap 205 is structurally and functionally similar to the cap 105 of the first embodiment, except that the cap 205 also encloses the shield and a major portion of the cartridge.

[0195] Spring Base The spring base 265 is fixedly mounted to the housing structure 240 at a proximal end and is adapted to receive and support the compressible torsion drive spring 108 .

[0196] Drive spring The drive spring 208 is pre-tensioned or wound and positioned between the spring base and the drive tube 280. The drive spring is further adapted to induce a torque on the drive tube, which may cause the medication to be expelled. The drive spring comprises a torsion and compressible section. The ability to drive the drive tube axially allows for the termination of the dose mechanism and allows for resetting of the drive tube.

[0197] Return spring Connector return spring 207 is positioned between spring base 265 and relock tube 279 and is adapted to bias the relock tube in a distal direction. In the return configuration, relock tube 279 abuts shield 210, which engages the connector, thereby allowing shield 210 and connector 270 to be returned together with relock tube 279.

[0198] Washing Assembly The cleaning assembly is structurally and functionally similar to the cleaning assembly of the first embodiment.

[0199] Housing Structure 19 illustrates a perspective view of features disposed on an inner surface of tubular housing structure 240 in an axial cut of the housing. As seen in FIG. 19, tubular housing structure 240 comprises an outer tubular portion 243 and an inner tubular portion 254. In the illustrated example, inner tubular portion 254 is integrally connected to the outer tubular portion. The outer tubular portion comprises an outer surface having an outer diameter and an inner surface having an inner diameter, the outer tubular portion adapted to accommodate a drive mechanism assembly and a relocking tube 279.

[0200] Housing structure 240 includes a guide structure including an axial surface portion 256 providing a sliding surface and rotational stop, and a helical surface portion 257 providing a sliding surface adapted to guide drive tube 280 during administration.

[0201] 20 details the inner tubular portion 254 in a perspective view with the outer tubular portion 243 cut away. The inner tubular portion comprises a tubular drive tube engaging portion 254.1 for receiving a distal portion of the drive tube, and a tubular drive piston rod engaging portion 254.2 with threads 254.3 for threadably engaging the piston rod 209. The piston rod engaging portion further comprises a connector 254.4 for providing a snap connection with the cartridge holder 230.

[0202] Zero point adjustment mechanism As can be seen in FIG. 17, the piston washer is provided with external threads and ratchet arms to cooperate with threads and a toothed ring on the inner surface of the piston, thereby allowing zero point adjustment, similar to the method described for the first embodiment.

[0203] Drive mechanism The structure and function of the drive mechanism of the second embodiment are similar to those of the first embodiment. In particular, the drive tube 280 is axially splined to the piston rod. Figures 23A and 23B illustrate the drive tube 280 in perspective views from different angles. As seen in Figure 23, as a deviation with respect to the first embodiment, the drive tube 280 of the second embodiment comprises a closed guide track 284 comprising a first lateral portion 284.1, a right-handed helical portion 284.2, and a left-handed helical portion 284.3. The lateral guide portion 284.1 comprises a proximally oriented surface that provides a connector seat, where the connector seats before and after actuation of the drive tube. The lateral portion further comprises an abutment structure 283, comprising a distally oriented surface portion 283.1 that provides an abutment surface for abutting the connector during actuation. The right helical portion 284.2 comprises a distal surface that provides an abutment surface for the connector in response to premature release of shield pressure, i.e., a split dose prevention feature. The left helical portion 284.3 provides a ramp surface for rotating the connector at the end of the dose, thereby initiating a reset of the shield. As with the first embodiment 100, the drive tube of the injection device 200 comprises a guide structure comprising an axial surface portion 282 adapted to slidably engage an axial surface portion 256 of the housing in a rotationally locked arrangement, and a helical surface portion 289 for slidably engaging a helical surface portion 257 of the housing during administration.

[0204] The same considerations for incorporating a torsion spring into the drive mechanism of the second embodiment provide the same advantages as mentioned in the first embodiment.

[0205] Long and narrow shield structure 24 shows a perspective view of a cylindrical elongated shield structure 210. The proximal portion of the shield is to be disposed inside a connector 270 which is again disposed inside the housing portions 240, 260. The elongated shield structure 210 comprises a tubular portion with an outer surface having an outer diameter and an inner surface having an inner diameter. An axially extending rib 216 is positioned at the distal end ant protruding from the outer surface. The rib is adapted to cooperate with an internal rib of the cap 205.

[0206] The shield structure 210 further includes a radial guide 212 disposed at a proximal end and extending radially therefrom, whereby the shield is adapted to cooperate with a connector 270 .

[0207] The elongated shield structure 210 further comprises a proximal guide 214 positioned at the proximal end of the shield structure 210. In FIG. 24, the proximal face of the proximal guide can be seen. The proximal guide 214 is adapted to cooperate with the connector 270 and the relocking tube 279. The proximal guide 214 extends axially and circumferentially and comprises a first lateral portion 214.1, an axial portion 214.2, a right-handed helical portion 214.3, and a second lateral portion 214.4. The proximal guide 214 further comprises a notch 214.5 that provides a rotational lock for locking the shield in the shield start-up state, which can be returned to the unwrapped state. The notch provides a right-handed helical guide portion 214.6. The guide portions 214.1-214.4 are all surface portions and provide the proximal face of the proximal guide 214.

[0208] connector 22 shows a perspective view of a connector 270 disposed inside tubular housing portions 240, 260 and between elongated shield structure 110 and the drive tube. Connector 270 is adapted to establish a connection between shield 210 and drive tube 280 and to actuate drive tube 280. Connector 270 includes a distal guide 272 adapted to cooperate with proximal guide 114 of the shield. Distal guide 272 includes a circumferentially extending, distally oriented surface, lateral surface portion 272.1.

[0209] The connector further comprises a stepped helical track 274 for cooperating with the radial guide 212 of the shield. The stepped helical track comprises a distal lateral portion 274.1, a distal helical portion 274.2, a central lateral portion 274.3, a proximal helical portion 274.4, and a proximal lateral portion 274.5. Due to the helical portion of the stepped helical track, rotational movement of the shield 210 can be translated into proximal movement of the shield, and due to the lateral portion of the stepped helical track 274, a distally directed force on the shield can be translated to the connector 270, thereby causing the shield to move distally. If the shield exerts a distal force on the helical portion of the stepped helical track 244, the connector can move distally or both distally and rotationally.

[0210] The connector 270 comprises a first tubular portion 270.1 having a full 360 degree circumference and a second tubular portion 270.2 having two notches, whereby the remaining portion of the second tubular portion forms two axially extending tube portions 276. The first tubular portion comprises a stepped helical track 274, and the two axially extending tube portions 276 comprise a distal lateral surface 272.1 forming a distal guide 272, a first axial surface providing a first axial guide 276.1, and a second axial surface positioned clockwise relative to the first surface providing a second axial guide 276.2. A shield may be disposed within the first tubular portion 270.1 with a radial guide 212 extending through the stepped helical track 274. The axially extending tube portion 276 extends proximally from the inner surface of the first tubular portion 270.1 and therefore has a smaller diameter. A lateral surface portion 272.1 is provided on a distally oriented surface of the axially extending tube portion 276, and the diameter of the tube portion 276 corresponds to the diameter of the shield 210, so that the proximal guide 214 having a proximally oriented surface is adapted to cooperate with the lateral guide portion 272.1. The diameter of the axially extending tube portion 276 further corresponds to the diameter of the inner axial portion 244.2 of the central guide, whereby the axially extending tube portion 276 can cooperate with the inner axial portion 244.2. The connector 270 has an outer surface having an outer diameter and an inner surface having an inner diameter. 18, a cross-sectional view of the injection device 200, an outer surface of the connector first tubular portion 270.1 is disposed in close proximity to an inner surface of the tubular housing cap portion 260. An axially extending tube portion 276 surrounds the housing inner tubular portion 254 and the drive tube 280. The axially extending arm 276 is further adapted to cooperate with a central guide 244.1 of the housing, thereby guiding movement of the connector relative to the housing.

[0211] The connector 270 further includes an actuation tab 278 disposed at the proximal end of the axially extending tube portion 270.2 and extending radially from the inner surface, i.e., toward the center of the tubular portion. The actuation tab 278 extends into the drive tube closed guide track 284. The actuation tab 278 includes a first lateral portion 278.1 providing a proximally oriented contact surface adapted to engage a distally oriented surface 283.1 of an abutment structure in the lateral portion 284.1 of the closed guide track, thereby enabling proximal movement and actuation of the drive tube 280. The actuation tab 278 further includes a proximally oriented surface portion 278.2 adapted to engage a distally oriented surface of the closed guide track 284, such that the connector may be guided during a dose cycle such that a split dose may be prevented in response to premature release of proximal pressure on the shield. In response to guiding the proximal portion 278.2 of the actuation tab along the left helical guide portion 284.3, the shield relocking mechanism is actuated.

[0212] relocking tube The relock tube 279 comprises a first tubular portion 279.1 and a second tubular portion having two notches such that the remaining portion of the second tubular portion forms two axially extending tube portions 279.2. The relock tube comprises an axially extending guide track 279.4 that extends a relatively small distance from the proximal end (e.g., 1 / 10 of the length of the relock tube) to the distal end. The two axially extending tube portions 279.2 comprise an axial guide portion 279.5, a first lateral guide portion 279.6, a right helical portion 279.7, and a second lateral portion 279.8. The axially extending tube portion 279.2 further comprises an axial portion 279.9 that provides a rotation stop and an axial guide for the connector. The axially extending tube portion 279.2 extends proximally from the inner surface of the first tubular portion 279.1 and therefore has a smaller diameter. The helical and lateral guide portions 279.6-279.8 are provided on a distally oriented surface of the axially extending tube portion 279.2, and the proximal guide 214 having a proximally oriented surface is adapted to cooperate with the helical and lateral guide portions 279.6-279.8, since the diameter of the tube portion 279.2 corresponds to the diameter of the shield 210. The diameter of the axially extending tube portion 279.2 further corresponds to the diameter of the inner axial portion 244.2 of the central guide. The diameter of the first tubular portion corresponds to the diameter of the outer axial portion 244.1 of the central guide. An axially extending guide track 279.4 is adapted to cooperate with the central guide outer portion 244.1 such that the relock tube 279 is rotationally locked and axially guided between a distal position defined by a proximal end of the guide track 279.4 and a proximal position (FIG. 18 shows that there may be axial play between the outer portion 244.1 and the proximal end of the track). The relock tube 279 has an outer surface having an outer diameter and an inner surface having an inner diameter. As illustrated in FIG. 18, the outer surface of the relock tube first tubular portion 279.1 is disposed in close proximity to the inner surface of the housing outer tubular portion 243, and the return spring is located between the spring base 265 and the proximal edge of the relock tube 279 such that the relock tube may be biased distally in response to proximal movement.An axially extending tube portion 279.2 surrounds the housing inner tubular portion 254 and may cooperate with the connector's axially extending tube portion 270.2.

[0213] Detailed description of the operation of the device 25A-26B collectively illustrate the relative and functional arrangement of different structures during a series of states of the injection device 200, thereby illustrating the operation of the device in detail.

[0214] In one embodiment of the present disclosure, an injection device 200 for sequentially delivering multiple fixed doses comprises a housing with an elongated housing structure 240, a cartridge holder 230, and a housing insert 260, a shield with an internal thread, an elongated shield structure 210 and a needle tip 219, a needle hub 225 with a fixedly attached needle cannula 204, a cap 205 adapted to be removably mounted on the housing and cover a major portion of the shield, a cartridge 235 having a movably arranged cartridge plunger or piston 236, and a drive mechanism comprising a torsion drive spring 208, a drive tube 280, and a piston rod 209 having an external thread for cooperating with the internal thread of the housing, the piston rod being arranged in connection with the piston 236, and the torsion spring being adapted to provide a torque for rotating the drive tube 280 relative to the housing. The drive tube comprises a ratchet mechanism 281, 265.1 that ensures rotation in the administration direction and prevents the non-administration direction. The drive tube is axially splined with the piston rod, thereby allowing relative axial movement and preventing relative rotation. The drive tube is adapted to advance the piston rod in response to rotating the drive tube in a dispensing direction, and due to the threaded connection with the housing, the piston rod is adapted to advance the piston 236 in the cartridge 235 to eject the fixed dose. The drive mechanism is adapted to be activated by changing the drive tube from a distal position, where the drive mechanism is in a stationary mode, to a proximal position, where the drive mechanism is in a dispensing mode. In the distal position, the drive tube is rotationally locked to the housing. In the proximal position, the drive tube is rotationally unlocked from the housing, and the torque provided may rotate the drive tube through a predetermined angle to eject the fixed dose. In the stationary mode of the drive mechanism, the piston rod is rotationally and axially locked, where the piston rod is rotationally locked to the housing through the splined connection with the drive tube 280 and axially locked through the threaded connection with the housing.

[0215] The torsion spring 208 is pre-tensioned to deliver multiple doses without binding during use. The drive mechanism is adapted to change modes upon activation, and as described below, the drive mechanism is adapted to be repeatedly activated until the last dose is expelled.

[0216] The cap may be disposed in an axially locked position and an axially unlocked position. The cap may be repositioned by rotating the cap relative to the housing. When the cap is in the axially unlocked position, the cap may be removed from the housing.

[0217] The shield may be disposed in different positions. The initial position is defined by an initial angular position and a corresponding initial axial position. The disengaged position is defined by a disengaged angular position and a corresponding disengaged axial position. The disengaged distal position is defined by a disengaged angular position and a corresponding distally engaged axial position. The disengaged proximal position is defined by a disengaged angular position and a corresponding proximally engaged axial position. In the initial position, the shield is adapted to allow counterclockwise movement. In the disengaged position, the shield is adapted to prevent clockwise movement and allow clockwise movement. The shield does not engage with the connector in the sense that proximal movement of the shield is not translated into proximal movement of the connector, whereby the shield cannot actuate the drive tube in this position. In the disengaged distal position, the shield is adapted to prevent counterclockwise and distal movement of the shield and is further adapted to allow proximal movement. In the engaged distal position, the shield is further adapted to allow clockwise rotation if the applied torque exceeds a predetermined threshold. When the shield is in the initial and disengaged positions, the needle tip is covered by the shield. In the engaged position, the shield is adapted to be moved proximally from the engaged distal position, where the needle tip is not covered by the shield and pressure in the reservoir may be released, to an engaged proximal position, where the needle tip may extend further from the shield and be inserted into the subcutaneous layer of the subject. In this position, further proximal movement may be prevented by blocking the shield tip 119 relative to the needle hub 125. The shield may be manually operated between different positions by a user. As viewed with respect to the shield in the initial position, the disengaged position, the distal engaged position, and the proximal engaged position, a set of four different angles and axial positions is defined, i.e., three different angular positions and four different axial positions.

[0218] The connector may be positioned in an initial or first position defined by a first angle and a corresponding distal position, and the connector is allowed to move to a proximal position, guided along the rotationally locked relocking tube 279, until the connector 270 meets an axial stop on the housing or until the shield tip 219 abuts the hub 225. Thus, the connector may be further positioned in a second position defined by the first angular position and a proximal position. Additionally, the connector may be positioned in a third position defined by a second angular position and a corresponding distal position, the first and third positions being defined by the same axial position.

[0219] Figures 25A-26B collectively illustrate a portion of the injection device 200 arranged in different states and intermediate configurations, with the entire outer portion of the housing and cap cut away to illustrate a portion of the internal structure. Each illustrated state is illustrated in a view in which a portion of the internal components is hidden by the connector and relock tube, e.g., Figure 25B1, and each illustrated state is illustrated in a view in which an outer portion of the relock tube and a portion of the outer portion of the connector are removed, e.g., Figure 25B3. Some illustrated states are also provided in grayscale illustrations, e.g., Figure 25B2 corresponding to Figure 25B1, and Figure 25B4 corresponding to Figure 25B3.

[0220] Unpackaged state Figure 25A illustrates a portion of the injection device 200 in an unpackaged state, showing the shield structure 210, the cartridge holder 230, the connector 270, the drive tube 280 and return spring 207, the relock tube 279, and the spring base 265. Figure 25A1 illustrates a portion of the injection device in black and white, while Figure 25A2 illustrates the same in greyscale to better illustrate the different components of the structure.

[0221] Cap unlocked The first user action is to rotate the cap counterclockwise until it reaches the axially unlocked position, which changes the shield from the initial position to the disengaged position, thereby changing from the unwrapped state to the cap unlocked state, as shown in FIG. 25B1 and FIG. 25B2. In the cap unlocked state, the cap can be moved axially. The cap unlocked state is also referred to as the shield activated state as the shield activates the device without engaging the connector, or the shield disengaged state as the shield cannot activate the drive mechanism. In contrast to embodiment 100, the shield 210 of embodiment 200 is not necessarily axially locked to the housing in this state, but since the shield does not engage the connector, axial movement cannot be transferred from the shield to the connector, and the connector cannot move to activate the drive tube 280. When the shield's radial guide 212 engages the stepped helical track 274 of the connector 270, the radial guide 212 abuts a proximal surface of the stepped helical track's distal helical guide portion 274.2 during the shield's proximal spiral movement from the initial to the disengaged position. In the disengaged position, the radial guide rests on the central lateral portion 273.4 and is not proximally present on the track 274. During the shield's proximal spiral movement, the shield moves the relock tube 279 proximally against the bias of the return spring 208, and in the disengaged position, the axially extending portion 279.2 of the relock tube has moved into the notch 214.5, thereby providing the rotational lock. When the shield is in the disengaged position, the right helical portion 279.7 of the relock tube abuts the right helical guide portion 214.6 of the notch and the right helical portion 214.3 of the proximal guide, thereby biasing the shield distally. A distal force is transferred from the shield to the connector through the abutment between the radial guide 212 and the track 274, thereby biasing the connector distally as well. Thus, in the following conditions, the relock tube 279, shield 210, and connector are biased distally. In FIG. 25B, the shield does not appear to extend to the spring base and therefore is not compressed.However, even if the illustrated embodiment is slightly inaccurate, the shield is at least slightly compressed in this state, otherwise components would rattle inside the device when going from up to down or vice versa.

[0222] Cap removed A second user action is to pull the cap in a distal direction, which causes the device to change from the cap unlocked state to the cap removed state.

[0223] As the cap is not shown in FIGS. 25A-26B, FIGS. 25B1 and 25B2 also illustrate the state in which the cap has been removed.

[0224] Shield engaged or activated A third user action is to rotate the shield, which is in the disengaged or unactivated position (because the drive mechanism cannot be activated), in a counterclockwise direction until it reaches the engaged distal or activated position, thereby changing the device from the uncapped state to the shield unlocked state.

[0225] From the disengaged position of the shield, to the engaged distal position of the shield shown in Figures 25C1 and 25C2, the shield rotates in a proximal helical movement guided by distal helical portion 274.4, followed by a pure rotational movement guided by proximal lateral portion 274.5. During the proximal helical movement of the shield along distal helical portion 274.4, right helical guide portion 214.6 of the notch and right helical portion 214.3 of the shield abut and slide against right helical portion 279.7 of the relock tube, thereby forcing the rotationally locked relock tube 279 in a proximal direction. During pure rotational movement of the shield, the abutment between the helical portion 279.7 of the relock tube and the helical portions 214.7, 214.3 of the shield shifts to an abutment between only the right helical portions 214.3, 279.7, and then to an abutment between the second lateral portion 214.4 of the proximal guide and the first lateral guide portion 279.6 of the relock tube. Because the abutment surface between the second lateral portion 214.4 of the shield and the first lateral portion 279.6 of the relock tube extends in a direction perpendicular to the biasing force of the return spring, the abutment provides a rest position for the relock tube 279 and the shield 210. Due to the biasing force and the abutment between the lateral portions 214.4, 279.6, a releasable locking mechanism is provided between the shield 210 and the relock tube 279. A torque exceeding a release threshold torque is required to release the lock. During the helical movement of the shield, the first transverse surface portion 214.1 of the proximal guide of the shield and the transverse surface portion 272.1 are abutted, and during the pure rotational movement, the shield slides relative to the connector until the abutment between the axial portion 276.1 of the axially extending portion 276 and the axial portion 214.2 of the axial guide. Therefore, releasing the lock and thereby establishing the abutment between the helical portion 214.3, 279.7 of the shield and the relocking tube also disengages the shield and the transverse portions 214.1, 272.1 of the connector. Another axial portion 276.2 of the axially extending tube portion 276 of the connector is rotationally locked in the counterclockwise direction relative to the rotationally locked axial portion 279.9 of the relocking tube, which is slidably arranged in the central guide 244 engaged in the axial track 279.4. The actuation tabs 278 of the connector seat within lateral portions 284.1 of the closed guide tracks within the drive tube.In the engaged distal position, the shield is adapted to move the connector proximally to actuate the drive tube.

[0226] Administration status A fourth user action is to push the shield in a proximal direction from the engaged distal position until it reaches the engaged proximal position, thereby changing the device from the shield unlocked state to the dispensed state. The dispensed state is illustrated by the configuration shown in Figures 25D-25E.

[0227] From the shield engaged distal position to the shield engaged proximal position shown in FIGS. 25D1 and 25D2, the shield moves in a proximal and pure axial movement guided by the relock tube moving along central guide 144. During the proximal movement of the shield, the shield causes the engaged relock tube 179 to translate proximally to compress the return spring 208, and further, the shield causes the engaged connector to translate proximally, whereby the actuation tab 278 engages the proximal surface of the closed guide track lateral portion 284.1, and the drive tube is also translated proximally. The drive tube has thereby been moved from a distal position where it is rotationally locked to the housing to a proximal position where it is rotationally unlocked from the housing. As illustrated in Fig. 25D2, the torque provided by drive spring 207 rotates the drive tube and the actuation tab slides out of lateral portion 284.1 and into right helical portion 284.2 of the closed guide track. Fig. 25D also reveals axial portion 282 for abutting axial portion 257 of inner tubular portion 254 of the housing (see Fig. 19) and helical portion 256 of the housing for abutting helical portion 289 of the drive tube (see Fig. 23).

[0228] 25E illustrates another arrangement of a dispense state following the arrangement of FIG. 25D where drive tube 180 has rotated further during dispense such that actuation tab 278 is disposed at the proximal end of right helical portion 284.2 and abutment just changes from right helical portion 284.2 to left helical portion 284.3. As in the above arrangement, the connector abuts against shield proximal guide axial portion 114.2 and relock tube first lateral guide portion 279.6 abuts against shield proximal guide second lateral portion 214.4 to transmit axial distal force from relock tube 279, through shield 210, to connector 270.

[0229] Initializing the automatic relocking mechanism When the drive tube stops rotating by reaching the end of dose, the proximal portion 278.2 of the activation tab 278 is disengaged in a right-handed helical trajectory, thereby preventing the connector from further moving in a distal direction. Because axial movement of the connector is not prevented by the drive tube, the connector will move axially in the distal direction and rotate in response to releasing pressure from the shield, which will move the connector into engagement with the left-handed helical portion 184.3 of the drive tube. This has initiated the automatic relocking mechanism.

[0230] Split dose prevention During the administration cycle, the activation tab 278 is engaged in the closed guide track 284. Thus, in response to lifting the shield from the skin, before the dose is completed, the activation tab will be blocked by the first lateral portion 284.1 or the right helical portion 284.2 of the guide track 284, and the drive tube will continue to rotate until the dose is completed. Upon completion of rotation, the connector will push the connector distally along with the activation tab and shield, preventing a split or interrupted dose, thereby ensuring that the next dose is obtained correctly. If the shield were to extend to a distal position, the needle tip would be positioned in the wash chamber, which could create overpressure in the wash chamber. Overpressure could unintentionally stop administration.

[0231] Relocked state A fifth user action is to release the axially directed force on the shield by lifting the needle tip 219 from the skin, whereby the shield, from the engaged proximal position, is moved distally until it reaches the disengaged position, thereby changing the device from the administered state, through the intermediate position shown in FIG. 25F, to the disengaged or unactivated state shown in FIG. 25G.

[0232] Automatic relocking mechanism FIG. 25F illustrates an intermediate position between the dispensed state and the disengaged state shown in FIG. 25G, where the drive tube has rotated into abutment with axial portion 257, thereby completing the dose. During rotation of the drive tube and in response to releasing pressure from the shield, activation tab 278 has shifted into abutment with left helical portion 284.3, and due to compression from return spring 207, activation tab 278 is caused to move along a left helical trajectory, thereby rotating connector 270 to a second angle and distal position. Force from the compression spring is transferred from the relock tube through the shield to the connector. During rotation of the connector, it is rotated due to abutment between the connector and axial portion 214.2 of the shield's proximal guide. Due to rotation of the shield and once the relock tube is rotationally locked, the abutment between the shield and the relock tube has shifted into abutment between right helical portion 214.3 of the shield and right helical guide 274.7 of the relock tube. The helical abutment surface allows axial movement of the relock tube 279 to be translated into rotational movement of the shield, and when the relock tube is biased distally, it is moved distally and the shield is rotated to a disengaged position, thereby disengaging the first lateral portion 214.1 of the shield's locking structure 215 from abutment with the lateral portion 272.1 of the connector's distally oriented lateral guide portion 272. Because the two lateral portions 214.1, 272.1 are lateral, they can be slid in response to the application of relative rotation.

[0233] With the cap on, with the cap locked A fifth user action is to place a cap, not illustrated, on the injection device 200, whereby a protrusion on the inner surface of the cap is inserted into an axial track on the housing, whereby the cap can be turned to place the device in a cap-locked state. The cap-locked state of the injection device 200 is not illustrated. When the cap 205 is rotated back to the locked state, it does not engage the shield, and therefore the shield is not pushed towards the initial position.

[0234] 26A and 26B illustrate two configurations in obtaining a second or subsequent dose if the connector does not rotate back to its first position. Once the relock tube is moved to its distal position, the connector 270 may be left in a third position having a second angular position, as shown in FIG. 25G2, or may be forced by the shield 210 to rotate to a first position having a first angular position as the radial guide slides distally along the proximal helical guide 274.4. In the latter case, the new dose will start from the configuration shown in FIG. 25B. In the first case, the new dose will start from the configuration shown in FIG. 25G2 and continue to the configuration shown in FIG. 26A, where the shield urges the relock tube proximally until the axial portion 214.2 of the shield abuts the axially extending portion 270.2 of the connector. In response to further rotation, the connector is forced back to the first position having a first angular position as shown in Figure 26. From here, the next dose continues as described beginning with Figure 25C.

[0235] Additional Embodiments The additional alternative embodiments described are not individually illustrated or provided with reference numbers, however the features of the alternative embodiments correspond to the features of the illustrated embodiment, whereby the features of the alternative embodiments provide one or more functions similar to or equivalent to the features of the illustrated embodiment.

[0236] In an alternative embodiment there is provided a drug delivery device for delivering a predetermined fixed dose, the drug delivery device comprising: a housing assembly; a drug reservoir having a piston; a drive mechanism comprising a piston rod for advancing a piston to expel the medicament, and a drive tube, the drive mechanism adapted to deliver a predetermined fixed dose in response to actuation; an actuation mechanism for actuating the drive mechanism in response to axially moving the drive-tube; the housing assembly comprises a guide structure for guiding the drive tube during activation and delivery of the dose, the guide structure comprising an axial portion providing a sliding surface for guiding the drive tube during activation and for providing a rotational stop that defines an end of the dose, and a helical portion providing a sliding surface adapted to guide the drive tube during administration; The drive tube includes an axial portion adapted to slidably engage the axial portion of the housing assembly for actuation and a helical portion for slidably engaging the helical portion of the housing assembly during administration.

[0237] Thereby a drug delivery device is provided, where the drive mechanism comprises a helix and an axial guide portion which provides a fixed dose upon actuation.

[0238] The helical portion of the housing assembly corresponds to the helical portion 157, 257 of the housing of the first and second embodiments, and the axial portion of the housing assembly corresponds to the axial portion 156, 256 of the housing of the first and second embodiments. The drive tube, torsion drive spring, and piston rod correspond to the drive tube 180, 280, torsion drive spring 108, 208, and piston rod 109, 209. The axial portion of the drive tube corresponds to the axial portion 182, 282 of the drive tube of the first and second embodiments, and the helical portion of the drive tube corresponds to the helical portion 189, 289 of the drive tube of the first and second embodiments.

[0239] In an alternative embodiment, the guide structure of the housing assembly is a closed guide that provides an actuation cycle for the drive-tube, and the start position and end of dose position of the drive-tube are the same.

[0240] In an alternative embodiment, the housing assembly further includes internal threads and the piston rod includes external threads that engage the internal threads of the housing assembly.

[0241] In an alternative embodiment, the drive tube is axially splined to the piston rod.

[0242] In an alternative embodiment, the drive mechanism further comprises a motor mechanism for imparting rotation of the drive tube to deliver the dose in response to actuation of the drive mechanism. The drive tube is axially splined to the piston rod, thereby rotationally locking the drive tube relative to the piston rod. The drive mechanism further comprises a return mechanism for axially moving the drive tube, thereby returning the drive tube after actuation, whereby the drive tube is reset to an initial position after actuation.

[0243] In an alternative embodiment, the trigger mechanism includes a movably disposed connector, the connector including an actuation tab, the actuation tab adapted to engage a surface portion of the drive tube in response to moving the connector axially, thereby operably connecting the connector to the drive mechanism and adapted to trigger the drive mechanism, the surface portion being oriented in a direction toward the actuation tab.

[0244] The connectors and actuation tabs correspond to the connectors 170, 270 and actuation tabs 178, 278 of the first and second embodiments. The surface portions correspond to the distally oriented surfaces 183.1, 283.1 of the first and second embodiments.

[0245] In an alternative embodiment, the drug delivery device comprises: a stationary state, in which the drive-tube is disposed in a first axial position and a first angular position, the drive-tube is locked to the housing, and the guide structure of the drive-tube abuts an axial portion of the housing assembly and a helical portion of the guide structure of the housing assembly; - a first dosing state, in which the drive-tube can be disposed in a second axial position and a first angular position, whereby the drive mechanism is activated; - a second dosing state, in which the helical portion of the guide structure is slidably disposed along the helical portion of the guide structure of the housing assembly, thereby allowing a dose to be expelled.

[0246] In an alternative embodiment, the connector is adapted to move the drive tube between a first axial position and a second axial position, whereby the medication delivery device is changed from a rest state to a first dosing state in response to moving the connector from the first axial position to the second axial position, and the drive mechanism is adapted to rotate the drive tube, whereby the injection device is changed from the first dosing state, through the second dosing state to a resting state in response to setting the injection device at the first dosing state.

[0247] the first and second positions of the connector are different from the first and second positions of the drive-tube; The axial distance between the first and second locations of the connector is greater than or equal to the axial distance between the first and second locations of the drive-tube.

[0248] In an alternative embodiment, the motor mechanism includes a torsion drive spring for rotating the drive tube by unwinding, the drive spring is fixed between the housing assembly and the drive tube, the drive spring is further compressible to move the drive tube axially distally during rotation, and the drive spring provides a return mechanism for returning the drive tube after actuation.

[0249] In an alternative embodiment, the drive spring comprises a compressible section, which corresponds to the compressible section 108.4 of the first and second embodiments.

[0250] In an alternative embodiment, the actuation tab includes a lateral surface portion and the engageable surface portion of the drive tube is lateral, whereby initiation of administration is provided by rotational movement induced by a torsional drive spring.

[0251] In an alternative embodiment, the drug delivery device includes a spring base rotatably disposed relative to a housing assembly, and a one-way ratchet mechanism is provided between the rotatably disposed spring base and the housing assembly, whereby the spring can be tensioned by rotating the spring base, whereby the torsion spring can be wound instead of or in addition to being pretensioned.

[0252] In an alternative embodiment, the motor mechanism includes a compressed drive spring, the actuation tab includes a helical surface portion, the engageable surface portion of the drive tube for actuating the drive tube includes a helical surface portion, the actuation tab is adapted to impart an initial rotation of the drive tube in the administration direction in response to engaging the tab and moving the drive tube between distal and proximal positions against the biasing force of the compression spring, and the helical portion of the housing assembly and the compression spring are adapted to provide further rotation of the drive tube in response to the initial position, whereby the complete fixed dose can be delivered.

[0253] The tabs correspond to tabs 183, 283 of the first and second illustrated embodiments.

[0254] In an alternative embodiment, the piston rod includes an axially extending raceway and the drive tube includes an inward protrusion adapted to slidably engage the axial raceway, whereby the drive tube is rotationally locked relative to the piston rod.

[0255] In an alternative embodiment, the axial and helical portions of the housing's guide structure are axial and helical surface portions, respectively, and the axial and helical portions of the drive-tube's guide structure are axial and helical surface portions, respectively.

[0256] In an alternative embodiment, the movement of the connector from the first axial position to the second axial position is a pure axial movement.

[0257] In an alternative embodiment, the first axial position is a distal position and the second axial position is a proximal position.

[0258] In an alternative embodiment, the drug delivery device is an injection device.

[0259] In an alternative embodiment, an injection device includes a shield for operating the connector, the shield adapted to cover a portion of the needle cannula at a distal position and to expose the needle cannula at a proximal position, with the shield in the proximal position a needle can be inserted into a subject, and the shield adapted to move the connector between first and second axial positions in response to moving the shield from the distal to the proximal position, the first and second positions of the connector being the distal and proximal positions.

[0260] The shield and needle cannula correspond to the shields 110, 210 and needle cannulas 124, 224 of the first and second embodiments.

[0261] In an alternative embodiment, there is provided a drug delivery device 100, 200 for delivering a fixed dose, the drug delivery device comprising: a housing assembly; a drug reservoir having a piston; a drive mechanism comprising a piston rod 109, 209 operably disposed within the housing assembly and adapted to advance the piston to expel medicament during dosing, and a drive tube 180, 280 operably disposed with the piston rod 109, 209, the drive tube 180, 280 being axially movable relative to the housing assembly and adapted to be rotationally blocked in a stationary state and adapted to be axially movable and rotatable relative to the housing in a dosing state, the drive mechanism being adapted for axial movement and rotation of the drive tube 180, 280 in the dosing state, thereby advancing the piston rod 109, 209 to deliver a fixed dose in response to actuation; an actuation mechanism for actuating the drive mechanism in response to axially moving the drive-tube; the housing assembly comprises a guide structure for guiding the drive tube during actuation and delivery of the dose, the guide structure comprising an axial portion 156, 256 providing a sliding surface for guiding the drive tube during actuation and for providing a rotational stop that defines an end position of the dose, and a helical portion 157, 257 providing a sliding surface adapted to guide the drive tube 180, 280 during administration; a drive tube (180, 280) comprising an axial portion adapted to slidably engage an axial portion (182, 282) of the housing assembly for actuation and a helical portion (189, 289) for slidably engaging a helical portion of the housing assembly during administration; The drug delivery device 100, 200 whereby the drive tube 180, 280 is guided along the axial portion 156, 256 without rotation, thereby allowing it to be changed from a stationary state to a dosing state during activation, and whereby the drive tube 180, 280 can be axially moved and rotated by the drive mechanism in the dosing state, whereby the drive tube 180, 280 is guided along the helical portion 189, 289 to the end position of the dose, thereby allowing it to be changed from a dosing state to a stationary state in response to activation of the drive mechanism.

[0262] In an alternative embodiment, the housing assembly further comprises internal threads and the piston rod 109, 209 comprises external threads that engage with the internal threads of the housing assembly, whereby the piston rod is operably disposed within the housing.

[0263] In an alternative embodiment, the drive tube 180, 280 is axially splined to the piston rod, thereby permitting relative axial movement and preventing relative rotation, such that the piston rod 109, 209 is advanced in response to rotation of the drive tube (180, 280), thereby operatively disposing the drive tube with the piston rod.

[0264] In an alternative embodiment, the piston rod is axially splined to the housing assembly whereby the piston rod is axially movable and rotationally locked relative to the housing assembly; the drive tube further comprises internal threads, and the piston rod further comprises external threads for threadably engaging the internal threads of the drive tube whereby the piston rod is operatively disposed with the housing assembly and the drive tube, the piston rod being advanced upon rotation of the drive tube; and the drive mechanism comprises a motor mechanism comprising a compression drive spring for axially moving the drive tube and the piston; the medication delivery device further comprising a connector having an angled actuation tab adapted to engage an angled surface of the drive tube and impart an initial rotation of the drive tube in the administration direction in response to engagement between the actuation tab and the drive tube against the biasing force of a compressed drive spring; The stationary state includes that the drive-tube can be disposed in a home position, the drive-tube can be disposed in a first axial position, the drive-tube is permitted to move in one axial direction and blocked by the housing in the other axial direction, and in a first angular position, the drive-tube is rotationally blocked by the housing in one direction and constrained in the other rotational direction by the drive mechanism, the guide structure of the drive-tube abuts an axial portion of the housing assembly and a helical portion of the guide structure of the housing assembly, The administration status is the drive tube is in a first dosing position, the drive tube being capable of being disposed in a second axial position and a first angular position, and an activation tab engages the drive tube against the biasing force of a compressed drive spring, thereby activating the drive mechanism; - a second dispensing position, in which the drive tube can be positioned at an axial position between the first and second axial positions, as well as at an angular position different from the first angular position, and in which the helical portion (189, 289) of the guide structure is slidably positioned at any position along the helical portion (157, 257) of the guide structure of the housing, whereby a dose can be expelled; the drive tube and the piston move together as the position of the drive tube changes from the home position to the first dispense position; the drive tube is rotatable relative to the piston rod in response to an angular position of the drive tube being changed from a first dispense position to a second dispense position, the change in angular position relative to the housing being induced by a helical guide surface of the housing and a compressed drive spring; At the same time, the drive tube is movable with the piston rod in response to the angular position of the drive tube being changed from the first dispense position to a home position, where a change in axial position relative to the housing is induced by a helical guide surface of the housing and a compressed drive spring; Thereby, the fixed dose has been delivered when the drive tube returns to a home position in response to actuation of the drive mechanism.

[0265] Further embodiments In a further embodiment, the drug delivery device comprises an integrated reusable needle having a needle wash chamber 120 .

[0266] In an alternative embodiment, the drug delivery device includes an integrated needle magazine and stores a plurality of needles.

[0267] First List of Embodiments 1. A drug delivery device (100, 200) for delivering a fixed dose, the drug delivery device comprising: a housing assembly; a drug reservoir having a piston; - a drive mechanism comprising a piston rod (109, 209) for advancing a piston to expel medicament during administration, and a drive tube (180, 280) connected to the piston rod (109, 209), the drive tube (180,) being adapted to be rotatably arranged during administration, thereby advancing the piston rod (109, 209), the drive mechanism being adapted to deliver a predetermined fixed dose in response to actuation; an actuation mechanism for actuating the drive mechanism in response to axially moving the drive-tube; the housing assembly comprises a guide structure for guiding the drive tube during actuation and delivery of the dose, the guide structure comprising an axial portion (156, 256) providing a sliding surface for guiding the drive tube during actuation and for providing a rotational stop that defines an end of the dose, and a helical portion (157, 257) providing a sliding surface adapted to guide the drive tube (180, 280) during administration; The drive tube (180, 280) comprises an axial portion adapted to slidably engage with the axial portion (182, 282) of the housing assembly for actuation, and a helical portion (189, 289) for slidably engaging with the helical portion of the housing assembly during administration. 2. The drug delivery device as described in embodiment 1, wherein the guide structure (156, 157, 256, 257) of the housing assembly is a closed guide that provides an operating cycle for the drive tube, and the starting position and the end position of the dose of the drive tube are the same. 3. A drug delivery device as described in embodiment 1 or 2, wherein the housing assembly further comprises an internal thread, and the piston rod (109, 209) comprises an external thread that engages with the internal thread of the housing assembly. 4. The drug delivery device of any of embodiments 1-3, wherein the drive tube is axially splined to the piston rod. 5. The drive mechanism further comprises a motor mechanism for imparting rotation of the drive tube to deliver the dose in response to actuation of the drive mechanism; the drive tube is axially splined to the piston rod such that the drive tube (180, 280) is rotationally locked to the piston rod (109, 209); 5. The medication delivery device of any of embodiments 1-4, wherein the drive mechanism further comprises a return mechanism for axially moving the drive-tube thereby returning the drive-tube after actuation. 6. A drug delivery device as described in any of embodiments 1 to 5, wherein the trigger mechanism comprises a movably arranged connector (170, 270), the connector comprising an activation tab (178, 278) adapted to engage a surface portion (183.1, 283.1) of the drive tube in response to moving the connector in the axial direction, thereby operably connecting the connector to the drive mechanism and adapted to trigger the drive mechanism, and the surface portion (183.1, 283.1) is oriented in a direction toward the activation tab (178, 278). 7. A drug delivery device comprising: a stationary state, in which the drive-tube (180) is disposed in a first axial position and a first angular position, the drive-tube is locked to the housing, and the drive-tube guide structure (182, 189, 282, 289) abuts the housing assembly axial portion (156, 256) and the housing assembly guide structure helical portion (157, 257); a first dosing state, in which the drive-tube (180, 280) can be disposed in a second axial position and a first angular position, whereby the drive mechanism is activated; - a second dosing state, in which the helical portion (189, 289) of the guide structure is slidably positioned along the helical portion (157, 257) of the guide structure of the housing assembly, thereby allowing a dose to be expelled. 8. The drug delivery device of embodiment 7, wherein the connector (170, 270) is adapted to move the drive tube between a first axial position and a second axial position, whereby the drug delivery device (100, 200) is changed from a rest state to a first dosing state in response to moving the connector (170, 270) from the first axial position to the second axial position, and the drive mechanism is adapted to rotate the drive tube, whereby the injection device is changed from the first dosing state, through the second dosing state, to a resting state in response to setting the injection device at the first dosing state. 9. A drug delivery device as described in embodiments 1 to 8, wherein the motor mechanism comprises a torsional drive spring (108, 208) for rotating the drive tube by unwinding, the drive spring (108, 208) is fixed between the housing assembly and the drive tube (180, 280), the drive spring is further compressible to move the drive tube axially distally during rotation, and the drive spring provides a return mechanism for returning the drive tube after activation. 10. The drug delivery device of embodiment 9, wherein the drive spring (108, 208) comprises a compressible section (108.4). 11. The drug delivery device of embodiment 9 or 10, wherein the activation tab (178, 278) has a lateral surface portion and the engageable surface portion (183.1, 283.1) of the drive tube is lateral, whereby initiation of administration is provided by a rotational movement induced by a torsional drive spring. 12. The medication delivery device of any of embodiments 1-8, wherein the motor mechanism comprises a compression drive spring, the actuation tab (178, 278) comprises a helical surface portion, the engageable surface portion (183.1, 283.1) of the drive tube for actuating the drive tube comprises a helical surface portion, the actuation tab is adapted to impart an initial rotation of the drive tube in the administration direction in response to engaging the tab (183, 283) and moving the drive tube between distal and proximal positions against the biasing force of the compression spring, and the helical portion (157.257) of the housing assembly and the compression spring are adapted to provide further rotation of the drive tube in response to the initial position, whereby a complete fixed dose can be delivered. 13. A drug delivery device as described in any of embodiments 1-12, wherein the piston rod (109, 209) has an axially extending track (109.2) and the drive tube (180, 280) has an inward protrusion (180.2) adapted to slidably engage with the axial track (109.2), thereby rotationally locking the drive tube (180, 280) relative to the piston rod (109, 210). 14. A drug delivery device as described in any of embodiments 1 to 13, further comprising a shield (110, 210) for operating the connector (170, 270), the shield adapted to cover a portion of the needle cannula (124) at a distal position and to expose the needle cannula at a proximal position, with the shield in the proximal position a needle can be inserted into the subject, and the shield adapted to move the connector (170, 270) between first and second axial positions in response to moving the shield from the distal to the proximal position, the first and second positions of the connector being the distal and proximal positions. 15. The drug delivery device of embodiment 1 or 2, wherein the piston rod is axially splined to the housing assembly, whereby the piston rod is axially movable and rotationally locked relative to the housing assembly; the drive tube (180, 280) further comprises an internal thread, and the piston rod (109, 209) further comprises an external thread for threadably engaging with the internal thread of the drive tube (180, 280), whereby the piston rod is operatively connected to the housing assembly and the drive tube, and the piston rod is advanced during rotation; and the motor mechanism comprises a compressed drive spring for axially moving the drive tube and the piston, whereby the drive mechanism, and the drive and return guides are adapted to return the drive tube to the first position.

[0268] Second List of Embodiments 1. A drug delivery device (100, 200) for delivering a fixed dose, the drug delivery device comprising: a housing assembly; a drug reservoir having a piston; a drive mechanism comprising: a piston rod (109, 209) operably disposed within the housing assembly and adapted to advance the piston to expel medicament during dosing; and a drive tube (180, 280) operably disposed with the piston rod (109, 209), the drive tube (180, 280) being axially movable relative to the housing assembly and adapted to be rotationally blocked in a stationary state and adapted to be axially movable and rotatable relative to the housing in a dosing state, the drive mechanism being adapted for axial movement and rotation of the drive tube (180, 280) in the dosing state, thereby advancing the piston rod (109, 209) to deliver a fixed dose in response to actuation; an actuation mechanism for actuating the drive mechanism in response to axially moving the drive-tube; the housing assembly comprises a guide structure for guiding the drive tube during actuation and delivery of the dose, the guide structure comprising an axial portion (156, 256) providing a sliding surface for guiding the drive tube during actuation and for providing a rotational stop that defines an end position of the dose, and a helical portion (157, 257) providing a sliding surface adapted to guide the drive tube (180, 280) during administration; a drive tube (180, 280) comprising an axial portion adapted to slidably engage an axial portion (182, 282) of the housing assembly for actuation and a helical portion (189, 289) for slidably engaging a helical portion of the housing assembly during administration; A drug delivery device (100, 200) whereby the drive tube (180, 280) is guided along the axial portion (156, 256) without rotation, thereby allowing it to be changed from a stationary state to a dosing state during actuation, and whereby the drive tube (180, 280) can be axially moved and rotated by the drive mechanism in the dosing state, whereby the drive tube (180, 280) is guided along the helical portion (189, 289) to an end position of the dose, thereby allowing it to be changed from a stationary state in response to actuation of the drive mechanism. 2. The drug delivery device as described in embodiment 1, wherein the guide structure (156, 157, 256, 257) of the housing assembly is a closed guide that provides an operating cycle for the drive tube, and the starting position and the end position of the dose of the drive tube are the same. 3. A drug delivery device as described in embodiment 1 or 2, wherein the housing assembly further comprises an internal thread, and the piston rod (109, 209) comprises an external thread that engages with the internal thread of the housing assembly. 4. A drug delivery device as described in any of embodiments 1 to 3, wherein the drive tube is axially splined to the piston rod, thereby allowing relative axial movement and preventing relative rotation, whereby the piston rod (109, 209) is advanced in response to rotation of the drive tube (180, 280). 5. The drive mechanism further comprises a motor mechanism for imparting rotation of the drive tube to deliver the dose in response to actuation of the drive mechanism; a drive tube is axially splined to the piston rod such that the drive tube (180, 280) is axially movable and rotationally locked relative to the piston rod (109, 209); 5. The medication delivery device of any of embodiments 1-4, wherein the drive mechanism further comprises a return mechanism for axially moving the drive-tube thereby returning the drive-tube after actuation. 6. A drug delivery device as described in any of embodiments 1 to 5, wherein the trigger mechanism comprises a movably arranged connector (170, 270), the connector comprising an activation tab (178, 278) adapted to engage a surface portion (183.1, 283.1) of the drive tube in response to moving the connector in the axial direction, thereby operably connecting the connector to the drive mechanism and adapted to trigger the drive mechanism, and the surface portion (183.1, 283.1) is oriented in a direction toward the activation tab (178, 278). 7. The rest state includes that the drive-tube (180) can be disposed in a home position, the drive-tube (180, 280) can be disposed in a first axial position, the drive-tube is permitted to move in one axial direction and blocked by the housing in the other axial direction, and in a first angular position, the drive-tube is rotationally blocked by the housing in one direction and constrained in the other rotational direction by the drive mechanism, the drive-tube's guide structure (182, 189, 282, 289) abuts the axial portion (156, 256) of the housing assembly and the helical portion (157, 257) of the housing assembly's guide structure, and the dispense state includes - a first dispensing position, in which the drive-tube (180, 280) can be disposed in a second axial position and a first angular position, whereby the drive mechanism is activated; - a second dispensing position, in which the drive tube can be positioned at an axial position between the first and second axial positions, as well as at an angular position different from the first angular position, and in which the helical portion (189, 289) of the guide structure is slidably arranged along the helical portion (157, 257) of the guide structure of the housing, thereby allowing a dose to be expelled. 8. The drug delivery device of embodiment 7, wherein the connector (170, 270) is adapted to move the drive tube between a first axial position and a second axial position, whereby a position of the drive tube (180, 280) is changed from a home position to a first dispensing position in response to moving the connector (170, 270) from the first axial position to the second axial position, and the drive mechanism is adapted to rotate the drive tube (180, 280) in response to activation of the drive mechanism by setting the drive tube (180, 280) at the first dispensing position, whereby a position of the drive tube (180, 280) is changed from the first dispensing position to the second dispensing position and to the home position. 9. A drug delivery device as described in embodiments 1 to 8, wherein the motor mechanism comprises a torsional drive spring (108, 208) for rotating the drive tube by unwinding, the drive spring (108, 208) is fixed between the housing assembly and the drive tube (180, 280), the drive spring is further compressible to move the drive tube axially during rotation, and the drive spring provides a return mechanism for returning the drive tube after activation. 10. The drug delivery device of embodiment 9, wherein the drive spring (108, 208) comprises a compressible section (108.4). 11. The drug delivery device of embodiment 9 or 10, wherein the activation tabs (178, 278) of the connectors (170, 270) have lateral surface portions and the engageable surface portions (183.1, 283.1) of the drive tube are lateral, whereby initiation of administration can be provided by rotational movement induced by the torsional drive spring in response to activation of the drive mechanism. 12. The medication delivery device of any of embodiments 1-8, wherein the motor mechanism comprises a compression drive spring, the actuation tab (178, 278) comprises a helical surface portion, the engageable surface portion (183.1, 283.1) of the drive tube for actuating the drive tube comprises a helical surface portion, the actuation tab is adapted to impart an initial rotation of the drive tube in the administration direction in response to engaging the tab (183, 283) and moving the drive tube between distal and proximal positions against the biasing force of the compression spring, and the helical portion (157.257) of the housing assembly and the compression spring are adapted to provide further rotation of the drive tube in response to the initial position, whereby a complete fixed dose can be delivered. 13. A drug delivery device as described in any of embodiments 1 to 12, wherein the piston rod (109, 209) has an axially extending track (109.2) and the drive tube (180, 280) has an inward protrusion (180.2) adapted to slidably engage with the axial track (109.2), whereby the drive tube (180, 280) is rotationally locked relative to the piston rod (109, 210) and allowed to move axially. 14. A drug delivery device as described in any of embodiments 1 to 13, further comprising a shield (110, 210) for operating the connector (170, 270), the shield adapted to cover a portion of the needle cannula (124) at a distal position and to expose the needle cannula at a proximal position, with the shield in the proximal position a needle can be inserted into the subject, and the shield adapted to move the connector (170, 270) between first and second axial positions in response to moving the shield from the distal to the proximal position, the first and second positions of the connector being the distal and proximal positions. 15. A piston rod is axially splined to the housing assembly whereby the piston rod is axially movable and rotationally locked relative to the housing assembly; the drive tube further comprises internal threads whereby the piston rod is operably disposed within the housing assembly; the piston rod further comprises external threads for threadably engaging the internal threads of the drive tube whereby the piston rod is operably disposed with the housing assembly and the drive tube; the piston rod is advanced upon rotation of the drive tube; and the drive mechanism comprises a motor mechanism comprising a compression drive spring for axially moving the drive tube and the piston; the medication delivery device further comprising a connector having an angled actuation tab adapted to engage an angled surface of the drive tube and impart an initial rotation of the drive tube in the administration direction in response to engagement between the actuation tab and the drive tube against the biasing force of a compressed drive spring; The stationary state includes that the drive-tube can be disposed in a home position, the drive-tube can be disposed in a first axial position, the drive-tube is permitted to move in one axial direction and blocked by the housing in the other axial direction, and in a first angular position, the drive-tube is rotationally blocked by the housing in one direction and constrained in the other rotational direction by the drive mechanism, the guide structure of the drive-tube abuts an axial portion of the housing assembly and a helical portion of the guide structure of the housing assembly, The administration status is the drive tube is in a first dosing position, the drive tube being capable of being disposed in a second axial position and a first angular position, and an activation tab engages the drive tube against the biasing force of a compressed drive spring, thereby activating the drive mechanism; - a second dispensing position, in which the drive tube can be positioned at an axial position between the first and second axial positions, as well as at an angular position different from the first angular position, and in which the helical portion (189, 289) of the guide structure is slidably positioned at any position along the helical portion (157, 257) of the guide structure of the housing, whereby a dose can be expelled; the drive tube and the piston move together as the position of the drive tube changes from the home position to the first dispense position; the drive tube is rotatable relative to the piston rod in response to an angular position of the drive tube being changed from a first dispense position to a second dispense position, the change in angular position relative to the housing being induced by a helical guide surface of the housing and a compressed drive spring; At the same time, the drive tube is movable with the piston rod in response to the angular position of the drive tube being changed from the first dispense position to a home position, where a change in axial position relative to the housing is induced by a helical guide surface of the housing and a compressed drive spring; 3. A medication delivery device as described in embodiment 1 or 2, whereby the fixed dose has been delivered when the drive tube returns to a home position in response to activation of the drive mechanism.

[0269] In the above description of the exemplary embodiments, different structures and means for providing the described functionality for the different components have been described to the extent that the concept of the invention is clear to those skilled in the art. The detailed construction and specification for the different components are considered to be the subject of normal design procedures carried out by those skilled in the art along the lines described herein.

Claims

1. A drug delivery device (100, 200) for delivering a fixed dose, said drug delivery device comprising: a housing assembly; a drug reservoir having a piston; a drive mechanism comprising a piston rod (109, 209) operably disposed within said housing assembly and adapted to advance said piston to expel medicament during dosing, and a drive tube (180, 280) operably disposed with said piston rod (109, 209), said drive tube (180, 280) being axially movable relative to said housing assembly and adapted to be rotationally blocked in a stationary state and adapted to be axially movable and rotatable relative to said housing assembly in a dosing state, said drive mechanism being adapted for axial movement and rotation of said drive tube (180, 280) in said dosing state, thereby advancing the piston rod (109, 209) to deliver said fixed dose in response to actuation; an actuation mechanism for actuating the drive mechanism in response to axial movement of the drive-tube; the housing assembly comprises a guide structure for guiding the drive tube during activation and delivery of a dose, the guide structure comprising an axial portion (156, 256) providing a sliding surface for guiding the drive tube during activation and for providing a rotational stop that defines an end position of a dose, and a circumferential portion (157, 257) providing a sliding surface adapted to guide the drive tube (180, 280) during administration; said drive tube (180, 280) comprising a guide structure comprising an axial portion (182, 282) adapted for slidable engagement with said axial portion (156, 256) of said housing assembly for actuation, and a circumferential portion (189, 289) for slidable engagement with said circumferential portion (157, 257) of said housing assembly during administration; a drive tube (180, 280) that is guided along the axial portion (156, 256) of the housing assembly without rotation, thereby allowing it to be changed from the stationary state to the dosing state during activation, and wherein the drive tube (180, 280) can be axially moved and rotated by the drive mechanism in the dosing state, thereby allowing it to be guided along the circumferential portion (157, 257) of the housing assembly to an end position of the dose, thereby allowing it to be changed from the dosing state to the stationary state in response to activation of the drive mechanism.

2. 2. The medication delivery device of claim 1, wherein the guide structure (156, 157, 256, 257) of the housing assembly is a closed guide that provides a working cycle of the drive-tube, and a starting position and an end-of-dose position of the drive-tube are the same.

3. 3. The drug delivery device of claim 1, wherein the circumferential portion (157, 257) of the guide structure of the housing assembly is a helical portion (157, 257) or a stepped portion having at least one step, and the circumferential portion (189, 289) of the guide structure of the drive tube (180, 280) is a helical portion (189, 289) corresponding to the helical portion (157, 257) of the housing assembly, or a stepped portion having at least one step corresponding to the stepped portion of the housing assembly.

4. 4. The drug delivery device of claim 1, wherein the drive tube is axially splined to the piston rod, thereby allowing relative axial movement and preventing relative rotation, whereby the piston rod (109, 209) is advanced in response to rotation of the drive tube (180, 280).

5. the drive mechanism further comprising a motor mechanism for imparting rotation of the drive tube to deliver a dose in response to actuation of the drive mechanism; the drive tube is axially splined to the piston rod such that the drive tube (180, 280) is axially movable and rotationally locked relative to the piston rod (109, 209); The medication delivery device of any one of claims 1 to 4, wherein the drive mechanism further comprises a return mechanism for axially moving the drive-tube thereby returning the drive-tube after actuation.

6. 6. The drug delivery device of claim 1, wherein the trigger mechanism comprises a movably arranged connector (170, 270), the connector comprising an actuation tab (178, 278) adapted to engage a surface portion (183.1, 283.1) of the drive tube in response to moving the connector in an axial direction, thereby operably connecting the connector to the drive mechanism and adapted to trigger the drive mechanism, the surface portion (183.1, 283.1) being oriented in a direction toward the actuation tab (178, 278).

7. The rest state includes that the drive-tube (180) can be disposed in a home position, the drive-tube (180, 280) can be disposed in a first axial position, the drive-tube is allowed to move in one axial direction and blocked by the housing assembly in another axial direction, and in a first angular position, the drive-tube is rotationally blocked by the housing assembly in one direction and constrained in the other rotational direction by the drive mechanism, the guide structure (182, 189, 282, 289) of the drive-tube abuts the axial portion (156, 256) of the housing assembly and the circumferential portion (157, 257) of the guide structure of the housing assembly, and the dispense state includes that the drive-tube (180, 280) can be disposed in a home position, the drive-tube (180, 280) can be disposed in a first axial position, the drive-tube is allowed to move in one axial direction and blocked by the housing assembly in another axial direction, and in a first angular position, the drive-tube is rotationally blocked by the housing assembly in one direction and constrained in the other rotational direction by the drive mechanism, the guide structure (182, 189, 282, 289) of the drive-tube abuts the axial portion (156, 256) of the housing assembly and the circumferential portion (157, 257) of the guide structure of the housing assembly, and the dispense state includes - a first dispensing position, in which the drive-tube (180, 280) can be arranged in a second axial position and in the first angular position, whereby the drive mechanism is activated; - a second dispensing position, in which the drive tube can be positioned at an axial position between the first and second axial positions, as well as at an angular position different from the first angular position, and in which the circumferential portion (189, 289) of the guide structure is slidably arranged along the circumferential portion (157, 257) of the guide structure of the housing assembly, whereby a dose can be expelled.

8. 8. The drug delivery device of claim 7, wherein the connector (170, 270) is adapted to move the drive tube between the first axial position and the second axial position, whereby a position of the drive tube (180, 280) is changed from the home position to the first dispensing position in response to moving the connector (170, 270) from the first axial position to the second axial position, and the drive mechanism is adapted to rotate the drive tube (180, 280) in response to activation of the drive mechanism by setting the drive tube (180, 280) at the first dispensing position, whereby a position of the drive tube (180, 280) is changed from the first dispensing position to the second dispensing position and to the home position.

9. The drug delivery device of claim 6, which is based on claim 5, wherein the motor mechanism comprises a torsion drive spring (108, 208) for rotating the drive tube by unwinding, the torsion drive spring (108, 208) is fixed between the housing assembly and the drive tube (180, 280), the torsion drive spring is further compressible to move the drive tube axially during rotation, and the torsion drive spring provides a return mechanism for returning the drive tube after activation.

10. 10. The medication delivery device of claim 9, wherein the torsion drive spring (108, 208) comprises a compressible section (108.4).

11. 11. The medication delivery device of claim 9 or 10, wherein the activation tab (178, 278) of the connector (170, 270) comprises a lateral surface portion and the surface portion (183.1, 283.1) of the drive tube is lateral, whereby initiation of administration can be provided by rotational movement induced by the torsion drive spring in response to activation of the drive mechanism.

12. 7. The medication delivery device of claim 6, wherein the motor mechanism comprises a compression drive spring, the actuation tab (178, 278) comprises a helical surface portion, the surface portion (183.1, 283.1) of the drive tube for actuating the drive tube comprises a helical surface portion, the actuation tab (183, 283) is adapted to impart an initial rotation of the drive tube in an administration direction in response to engaging a tab (183, 283) of the drive tube and moving the drive tube between its distal and proximal positions against the biasing force of the compression drive spring, and the circumferential portion (157, 257) of the housing assembly and the compression drive spring are adapted to provide further rotation of the drive tube in response to the initial rotation, whereby a complete fixed dose can be delivered.

13. 13. The drug delivery device of any one of claims 1 to 12, wherein the piston rod (109, 209) comprises an axially extending track (109.2) and the drive tube (180, 280) comprises an inward protrusion (180.2) adapted to slidably engage the axial track (109.2), whereby the drive tube (180, 280) is rotationally locked relative to the piston rod (109, 210) and allowed to move axially.

14. 9. The drug delivery device of claim 8, further comprising a shield (110, 210) for operating the connector (170, 270), the shield adapted to cover a portion of a needle cannula (124) at a distal position and to expose the needle cannula at a proximal position, with the shield in the proximal position the needle cannula can be inserted into a subject, the shield adapted to move the connector (170, 270) between the first and second axial positions in response to moving the shield from the distal position to the proximal position, the first and second axial positions of the connector being distal and proximal positions.

15. the piston rod is axially splined to the housing assembly whereby the piston rod is axially movable and rotationally locked relative to the housing assembly; the drive tube further comprises internal threads whereby the piston rod is operably disposed within the housing assembly; the piston rod further comprises external threads for threadably engaging the internal threads of the drive tube whereby the piston rod is operably disposed with the housing assembly and the drive tube, the piston rod being advanced during rotation of the drive tube; and the drive mechanism comprises a motor mechanism comprising a compression drive spring for axially moving the drive tube and the piston; the medication delivery device further comprising a connector having a ramped actuation tab adapted to engage a ramped surface of the drive tube and impart an initial rotation of the drive tube in an administration direction in response to engagement between the ramped actuation tab and the drive tube against a biasing force of the compressed drive spring; The resting state includes that the drive-tube can be disposed in a home position, the drive-tube can be disposed in a first axial position, the drive-tube is allowed to move in one axial direction and blocked by the housing assembly in another axial direction, and in a first angular position, the drive-tube is rotationally blocked by the housing assembly in one direction and constrained in the other rotational direction by the drive mechanism, the guide structure of the drive-tube abuts the axial portion of the housing assembly and a helical portion of the guide structure of the housing assembly, The administration state is - a first dispensed position, the drive tube being capable of being disposed in a second axial position and the first angular position, the ramped actuation tab engaging the drive tube against the biasing force of the compressed drive spring, thereby actuating the drive mechanism; a second dispensing position, in which the drive-tube can be positioned at an axial position between the first and second axial positions, as well as at an angular position different from the first angular position, and in which a helical portion of the guide structure of the drive-tube is slidably positioned at any position along the helical portion of the guide structure of the housing assembly, whereby a dose can be expelled; the drive tube and the piston move together as the position of the drive tube changes from the home position to the first dispense position; the drive tube is rotatable relative to the piston rod in response to the angular position of the drive tube being changed from the first dispense position to the second dispense position, the change in angular position relative to the housing assembly being induced by the helical portion of the housing assembly and the compression drive spring; at the same time, the drive tube is movable with the piston rod in response to the axial position of the drive tube being changed from the first dispense position to the home position, the change in axial position relative to the housing assembly being induced by the helical portion of the housing assembly and the compression drive spring; 3. A medication delivery device according to claim 1 or 2, whereby a fixed dose has been delivered when the drive tube returns to the home position in response to actuation of the drive mechanism.

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