MECHANISM UNIT FOR DRUG DELIVERY DEVICE AND DRUG DELIVERY DEVICE - Patent application

Abstract

A mechanism unit for a drug delivery device, comprising: a housing (10); a piston rod (30); and a dose setting and driving mechanism configured to perform a dose setting operation and a dose setting operation by transmitting a delivery force to the piston rod (30) to drive the piston rod (30) distally in the dose setting operation, wherein the dose setting and driving mechanism comprises a first driving member (40a), a second driving member (40b), and a clutch mechanism having at least two different states, a setting state and a delivery state, wherein in the setting state, the second driving member ( In the delivery state, the second drive member (40b) is rotatably fixed relative to the housing (10) at least against rotation in the delivery direction, and in the set state, the first drive member (40a) is rotatable relative to the second drive member (40b) at least in the delivery direction, and in the delivery state, the second drive member (40b) is non-rotatably locked relative to the first drive member (40a), at least against rotation of the second drive member (40b) relative to the first drive member in the delivery direction.

Description

[Technical Field]

[0001] The present disclosure relates to a mechanism unit for a drug delivery device. The present disclosure further relates to a drug delivery device including the mechanism unit, and a method for manufacturing the drug delivery device. [Background technology]

[0002] In drug delivery devices, particularly those operated by non-medically trained patients, it is paramount that the size of the dose to be delivered by the drug delivery device correspond as consistently as possible to the size set by the user while the device is being used to dispense a drug from a cartridge or reservoir. Drug delivery devices often use a piston rod that is moved by the device's drive mechanism and is positioned to drive a bung within the reservoir body of the drug-holding reservoir distally relative to the reservoir body to dispense the drug from the reservoir. During manufacture of the drug delivery device, the distance between the opposing distal ends of the piston rod and the proximal end of the bung can vary significantly after initial assembly of the device. From a manufacturing perspective, it may be possible to position the piston rod fairly accurately relative to the housing of the drive mechanism of the drug delivery device. However, it is usually difficult to ensure that the position of the bung relative to the reservoir body is accurately set, for example, for reservoirs with nominally the same liquid fill level due to the deformable materials typically used for the bung. Therefore, the initial position of the bung relative to the reservoir body may vary. While changes in the dimensions of the reservoir body can have a similar effect, the impact of the bung is more pronounced. The mentioned variations result in a large variation in the distance between the distal end of the piston rod and the proximal end of the bung in different devices after the devices are assembled. Therefore, the initial target distance between the piston rod and the bung to be achieved during the device assembly process must be selected to be large enough to take into account a wide range of possible positions of the bung relative to the reservoir body, for example, to avoid the piston rod already exerting undesirable pressure on the bung during assembly of the device when applying a mechanical preload to the bung. Therefore, the variability in the bung position often requires that a relatively large initial target distance be selected.

[0003] The defined initial position between the bung and the piston rod for various devices is achieved by a means that allows a variable connection between the drive mechanism and the reservoir or reservoir unit, i.e., that does not rely on fixed elements with defined positions in the respective units, the reservoir unit and the drive mechanism unit. Connection methods that allow a variable connection are, for example, adhesive or welded connections. However, if a more reliable connection were to be used, such as established by a securely fastening or locking feature, for example, for a form-fitting connection, the relative position between the bung and the piston rod after assembly of the device could vary considerably due to variations in the reservoir unit.

[0004] Before the first dose is administered to the patient, a so-called priming step may be used to achieve a defined position between the piston rod and the bung, and the user must perform a dose setting and delivery step before the first (self-)administration of the drug is performed. Such a procedure is often called an "air shot." However, this procedure remains unsatisfactory because it is uncertain whether the user will actually perform the step even if instructed to do so.

[0005] Furthermore, as the concentration of the drug in the reservoir increases, the initial distance between the piston rod and the bung may become so large that it is greater than the normal dose dispensed by the drug delivery device, for example, greater than the minimum settable dose or a larger dose, or even greater than the maximum settable dose dispensed by the drug delivery device in one dispensing operation. Thus, the first dose set to be dispensed is completely absorbed by the initial gap between the piston rod and the bung, which must be closed, and the drug is then dispensed by displacing the bung relative to the reservoir body. This is, of course, very problematic. Furthermore, because a significant gap may still exist after the first dose is dispensed, even if the priming dose is dispensed, the second dose may still be inaccurate.

[0006] An option for achieving a defined initial position is to set a dose after the device is assembled, conveniently before the device is provided to the user, and then activate the drive mechanism by dispensing the set dose until the piston rod reaches the desired position. However, drug delivery devices, particularly those configured to dispense variable, e.g., user-settable, doses, often include a mechanism for tracking the (end of) reservoir contents or the maximum amount dispensed from the reservoir. This mechanism is dimensioned to ensure that when the last dose is dispensed, some drug still remains in the reservoir, i.e., the reservoir is overfilled. This naturally corresponds to avoiding the risk of underdosing. Tracking mechanisms for tracking the (end of) reservoir contents usually have a tracking member that is moved toward an end position relative to the guide track when the dose is set, but is not moved relative to the guide track when the set dose is delivered. When the tracking member reaches the end position, the reservoir is considered empty. At the end position, (further) increase of the set dose is prevented by the tracking member.

[0007] Typically, drug delivery devices dispense doses in integer unit increments. Because the tracking element also moves during the first setting and dispensing of the dose, which is performed to eliminate the initial gap between the piston rod and the bung as described above, this results in the reservoir having to be overfilled with drug at least to an amount corresponding to the maximum initial distance between the piston rod and the bung when assembling various devices of nominally identical structure. This overfilled drug is therefore usually not dispensed and is therefore wasted. The amount of overfilled drug can be even greater than the maximum dose set in the device as described above. Summary of the Invention [Problem to be solved by the invention]

[0008] It is an object of the present disclosure to provide an improved assembly for a drug delivery device, an improved drug delivery device, and / or an improved method for manufacturing a drug delivery device. This object is achieved by the subject matter of the independent claims and may also be achieved by other subject matter disclosed. Further advantageous embodiments and improvements follow from the dependent claims and the following disclosure. [Means for solving the problem]

[0009] In one embodiment, there is provided a mechanism unit for a drug delivery device, the mechanism unit including: a housing having a proximal end and a distal end; a piston rod movable relative to the housing, e.g., movably held within the housing; and a dose setting and driving mechanism configured to perform a dose setting operation of setting a dose to be delivered and a dose setting operation of delivering the set dose by transmitting a delivery force to the piston rod to drive the piston rod in a distal direction relative to the housing in the dose setting operation, wherein the dose setting and driving mechanism mechanically cooperates with the piston rod to transmit the delivery force to the piston rod, and a first driving member axially fixed and rotatable relative to the housing, wherein rotation of the first driving member in the delivery direction relative to the housing moves the piston rod in the distal direction. The device includes a first drive member, which when rotated in a direction opposite to the delivery direction moves the piston rod proximally; a second drive member mechanically coupled to the first drive member and arranged to transmit a delivery force to the first drive member; and a clutch mechanism having at least two different states, a set state and a delivery state, wherein in the set state the second drive member is fixed to be non-rotatable relative to the housing at least in rotation in the delivery direction, and in the delivery state the second drive member is rotatable relative to the housing in the delivery direction, and in the set state the first drive member is rotatable relative to the second drive member and the housing at least in the delivery direction, and in the delivery state the second drive member is locked to be non-rotatable relative to the first drive member at least in rotation in the delivery direction.

[0010] Because the first drive member is rotatable relative to the second drive member in the delivery direction in a preset state, the piston rod can be moved distally, for example, before final assembly of the drug delivery device. This is preferably achieved by direct manual or automatic rotation of the first drive member, for example, by an auxiliary tool. This rotation allows the piston rod to move distally until the desired distance between the proximal end of the bung in the reservoir of the reservoir unit and the distal end of the piston rod is reached when the device is assembled, for example, by connecting the mechanism unit and the reservoir unit. This allows the desired distance between the bung and the piston rod to be accurately adjusted before the first dose delivery and the first operation of the drive mechanism, regardless of the bung position, reservoir size, or original fill level. In this way, one or more air shots can be avoided before using the drug delivery device to administer a drug to a patient. This not only means that there is no waste of medicine, but also significantly improves the ease of use and, therefore, safety of the drug delivery device after assembly.

[0011] In one embodiment, the mechanism unit is configured to be coupled to the reservoir unit to assemble the two units for the drug delivery device.

[0012] This allows the position of the piston rod to be adjusted before the drug delivery device is assembled in an operational state that can reach the patient or customer, which can be particularly advantageous when the mechanism unit is used for reservoir units of different designs that may have, for example, different positions of the bung.

[0013] In one embodiment, the first drive member is accessible from outside the housing for operation so that, in a set state, the position of the piston rod relative to the housing can be adjusted by rotating the first drive member, preferably before or after the mechanism unit and the reservoir unit are connected.

[0014] The first drive member being accessible from outside the housing allows the piston rod to be adjusted when the mechanism unit is already assembled but the drug delivery device is not yet fully assembled.

[0015] In one embodiment, the first drive member is accessible for operation from the distal end of the housing, and in a set state, the position of the piston rod relative to the housing is adjusted by rotation of the first drive member, which is done before the mechanism unit and the reservoir unit are coupled.

[0016] In one embodiment, the first drive member is accessible for operation from the proximal end of the housing, and in a set state, the position of the piston rod relative to the housing is adjusted by rotation of the first drive member, either before or after the mechanism unit and the reservoir unit are coupled.

[0017] The first drive member is accessible from the proximal end of the housing, allowing the piston rod to be adjusted before the drug delivery device is fully assembled and before or after the mechanism unit and the reservoir unit are coupled. The opening through which the first drive member is accessible is closed by a closure element, e.g., a button element, that provides a user interface for the drug delivery device.

[0018] In one embodiment, the second drive member is axially movable, e.g., distally, relative to the first drive member and the housing to switch between a set state and a delivery state. Preferably, distal movement of the second drive member relative to the first drive member and the housing from an initial position in the set state transitions the mechanism unit to the delivery state, and proximal movement of the second drive member in the delivery state relative to the first drive member and the housing transitions the mechanism unit to the set state.

[0019] In one embodiment, the first drive member is engaged with the piston rod. The piston rod is engaged with the housing. Preferably, the first drive member is directly engaged with the piston rod.

[0020] This allows movement of the first drive member relative to the housing to have a direct effect on the axial position of the piston rod relative to the housing.

[0021] In one embodiment, the first drive member is threadedly engaged with a piston rod, which is splined to the housing.

[0022] In one embodiment, the first drive member is rotatable relative to the piston rod, preferably in the delivery state and / or the set state.

[0023] The threaded engagement between the first drive member and the piston rod causes rotational movement of the first drive member and axial displacement of the piston rod, thereby allowing the piston rod to be moved to a desired position relative to the housing.

[0024] In one embodiment, the first drive member is splined to a piston rod, which is threadedly engaged with the housing.

[0025] In one embodiment, the first drive member is non-rotatably constrained relative to the piston rod in the delivery direction and in the direction opposite to the delivery direction, preferably in the delivery state and / or the set state.

[0026] This allows movement of the first drive member to have a direct effect on the axial position of the piston rod relative to the housing.

[0027] In one embodiment, the first drive member is fixed against proximal and distal movement relative to the housing, preferably in the delivery state and / or the set state.

[0028] In one embodiment, the first drive member and / or the second drive member is a sleeve.

[0029] In one embodiment, the piston rod extends through the first drive member and / or the second drive member.

[0030] In one embodiment, the first drive member includes a first locking feature and the second drive member includes a second locking feature. The first locking feature and the second locking feature are configured to interact to non-rotatably lock the first drive member and the second drive member against relative rotation in at least one and / or two directions. Preferably, the first locking feature and the second locking feature mechanically interact, e.g., when engaged with each other, the second drive member cannot rotate relative to the first drive member, at least in the delivery direction.

[0031] In one embodiment, the first locking feature is non-rotatable and axially immovable relative to the first drive member, and the second locking feature may be non-rotatable and axially immovable relative to the second drive member.

[0032] In one embodiment, the first locking feature engages with the second locking feature in the delivery state.

[0033] In one embodiment, the first locking feature and the second locking feature are disengaged in the set state.

[0034] In one embodiment, the first locking feature and the second locking feature are disengaged in the set state, and the first locking feature is rotatable relative to the second locking feature in the set state.

[0035] In one embodiment, the first locking feature engages with the second locking feature in the set state.

[0036] In one embodiment, the first locking feature and the second locking feature are configured such that when the first locking feature engages the second locking feature, the first locking feature is rotatable relative to the second locking feature in the delivery direction and is non-rotatably secured relative to the second locking feature in the opposite direction to the delivery direction, implying that the second drive member cannot rotate relative to the first drive member in the delivery direction.

[0037] In one embodiment, the first and second locking features are designed such that when the first locking feature engages with the second locking feature, the first drive member can occupy one of several stable positions relative to the second drive member, the angular distance between the stable positions being adjusted to, e.g., corresponding to, an angle through which the user must rotate the dose setting member to set, e.g., a minimum dose to be delivered by the drug delivery device, which may correspond to one unit increment.

[0038] In one embodiment, the first and second locking features are designed such that the distance between the stable positions is such that movement of the first drive member relative to the second drive member from one of the stable positions to the next immediately adjacent stable position results in an axial movement of the piston rod that corresponds to an axial movement of the piston rod during delivery of at most one unit increment of the dose.

[0039] In one embodiment, the first locking feature and the second locking feature are designed as mating ratchet teeth.

[0040] In one embodiment, the dose setting and driving mechanism includes a dose setting member that is movable relative to the housing from an initial position to a dose setting position in a set state to set a dose of drug, particularly when the device is fully assembled.

[0041] In one embodiment, the dose setting member is non-rotatably constrained relative to the second drive member in the delivery state and is rotatable relative to the second drive member in the set state.

[0042] In one embodiment, the first drive member is non-rotatably constrained in the delivery state relative to the dose setting member and the second drive member in a direction opposite to the delivery direction. Further, the first drive member may be rotatable in the delivery state relative to the dose setting member and the second drive member in the delivery direction.

[0043] In one embodiment, the first drive member is rotatable in the delivery direction relative to the dose setting member and the second drive member in the set state. Further, the first drive member may be rotatable in the delivery direction and in the direction opposite to the delivery direction relative to the dose setting member and the second drive member in the set state.

[0044] In one embodiment, the mechanism unit includes an energy storage unit configured such that, in a setting state, energy is stored in the energy storage unit upon movement of a setting member, preferably a dose setting member, by a user, and configured such that, in a delivery state, the stored energy in the energy storage unit is released to support the delivery process. The energy storage unit may be a drive spring.

[0045] In one embodiment, there is provided a drug delivery device preferably further comprising a mechanism unit as described above.

[0046] In one embodiment, the drug delivery device comprises a reservoir unit, which includes or is provided to hold a reservoir that holds the drug.

[0047] In one embodiment, the reservoir is a cartridge.

[0048] In one embodiment, the drug delivery device is an injection device, for example a needle-based injection device, preferably a pen-type injection device.

[0049] In one embodiment, there is provided a method of manufacturing a drug delivery device, comprising: a) providing a reservoir unit including a reservoir containing a drug, wherein a stopper is movably retained within the reservoir, the reservoir being retained within a reservoir unit body; b) providing the mechanism unit described above; c) determining the location of the plug relative to the reservoir unit body; d) determining a desired piston rod position of the piston rod relative to the housing based on the determined bung position, the desired piston rod position being determined such that the piston rod and the bung are disposed at a predetermined distance from each other when the mechanism unit and the reservoir unit are coupled, and determining a specific displacement distance that the piston rod must be displaced distally relative to the housing to reach the desired piston rod position; e) in a set state of the mechanism unit, rotating the first drive member relative to the second drive member to displace the piston rod by a specific displacement distance relative to the housing; f) after or before step e), connecting the reservoir unit and the mechanism unit to each other.

[0050] As a result, rotation of the first drive member accurately positions the distal end of the piston rod relative to the proximal end of the bung. Therefore, the size of the first dose delivered by the drug delivery device accurately corresponds to the size set by the user. Therefore, there is no need for an air shot and no risk of the patient receiving an incorrect dose.

[0051] These and other aspects, advantages and benefits will become apparent from the embodiments described hereinafter.

[0052] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0053] [Figure 1] FIG. 1 shows a top view of a drug delivery device according to a first embodiment of the present disclosure. [Figure 2] 2 shows an exploded view of the components of the device of FIG. 1. [Figure 3a] 2 shows a cross-sectional view of the proximal end of the device of FIG. 1 in a configured state. [Figure 3b] 2 shows a cross-sectional view of the proximal end of the device of FIG. 1 in a dose delivery state. [Figure 4] 1 shows a detail of a device according to a second embodiment of the present disclosure in cross section. [Figure 5a] 10 shows a detail of a device according to a third embodiment of the present disclosure in cross section. [Figure 5b] A detail of the embodiment of FIG. 5a is shown. [Figure 6a] 1 shows a cross-sectional view of one embodiment of a drive member in a set state. [Figure 6b] 6b shows a cross-sectional view of the drive member of FIG. 6a in a delivery state. [Figure 7a] 13 shows a cross-sectional view of another embodiment of a drive member in a set state. [Figure 7b] FIG. 7b shows a cross-sectional view of the drive member of FIG. 7a in a delivery state. [Figure 8] 1 shows a schematic diagram of an interface in a drive member. [Figure 9a] 13 shows a cross-sectional view of yet another embodiment of a drive member in a delivery state. [Figure 9b] 9b shows a cross-sectional view of the embodiment of FIG. 9a in a set state. [Figure 9c] 9a and 9b show further cross-sectional views of the embodiment of FIG. 9a and FIG. 9b. [Figure 9d] 9a and 9b show yet another cross-sectional view of the embodiment of FIG. 9a and FIG. 9b. [Figure 10a] 13 shows a cross-sectional view of yet another embodiment of a drive member in a set state. [Figure 10b] 10b shows a cross-sectional view of the embodiment of FIG. 10a in a delivery state. [Figure 10c] 10a and 10b show further cross-sectional views of the embodiment of FIG. [Figure 10d] 10a and 10b show yet another cross-sectional view of the embodiment of FIG. [Figure 11] 10a-10d show views of the surface of a first drive member according to any one of the embodiments of FIGS. 9a-10d; DETAILED DESCRIPTION OF THE INVENTION

[0054] FIG. 1 shows a drug delivery device in the form of an injection pen. The device has a distal end (left end in FIG. 1 ) and a proximal end (right end in FIG. 1 ). The components of the drug delivery device are shown in FIG. 2 . The drug delivery device includes a body or housing 10, a reservoir unit body (or cartridge holder) 20, a piston rod (or lead screw) 30, a drive member (or drive sleeve) 40, a nut 50, a dose setting member (or dose indicator or number sleeve or scale drum) 60, a button 70, a dial grip or dose selector 80, a torsion spring 90, a reservoir (or cartridge) 100, a gauge element 110, a clutch plate 120, a clutch spring 130, and a bearing 140. A needle arrangement (not shown) with a needle hub and needle cover is provided as an additional component and can be replaced as described above. All components are concentrically arranged around the common main axis I of the mechanism ( FIG. 3 b).

[0055] The housing 10, or body, is a generally tubular casing element having a proximal end with an enlarged diameter. The housing 10 provides a location for the liquid medication reservoir 100 and the reservoir unit body 20. As shown in Figures 1 and 2, the housing includes a first window 11a and a second window (or lens) 11b that are incorporated into the housing body by, for example, twin-shot molding. The windows 11a, 11b are molded from a translucent (and preferably transparent) material during the first shot, and the outer cover of the housing is molded from an opaque material during the second shot.

[0056] In the embodiment of Figures 1-3b, the housing includes an insert 12 as a unitary member disposed as an interior wall near the distal end of the housing. The insert 12 is molded into a translucent material. Alternatively, the insert, or portions thereof, may be formed into an opaque material or as a separate component, as shown in the embodiment of Figure 4.

[0057] The insert 12 is a cup-shaped component having a sidewall 13 and a tube 14 extending therethrough, thereby forming an annular space therebetween. Arms 15 extend radially outward from the sidewall 13. A bottom wall 16 connects the sidewall 13 and the tube 14 on the distal side of the insert 12, while the opposite proximal side is open. The insert 12 has various interfaces. For example, the tube 14 of the insert 12 includes internal threads 17 that engage with the piston rod 30. Additionally, the radial space between the tube 14 and the outer sidewall 13 can provide a bearing area for receiving the drive spring 90 and the clutch spring 130. Furthermore, spline teeth 18 are provided on the insert 12 that engage corresponding spline teeth 41 on the distal end of the drive member 40. The teeth 18 interact with the drive member 40 to rotatably couple and decouple the drive member and the housing 10.

[0058] In the embodiment of Figure 4, the insert is an integral part of the inner housing shell, which is partially surrounded by the outer housing shell. The shells are formed by two successive injection molding shots so that the shells are permanently attached to each other. For example, the inner shell may be formed from a transparent or translucent material, while the outer shell is formed from an opaque material.

[0059] In the embodiment of FIGS. 5a and 5b, insert 12 is partially formed as a single component with housing 10 and partially formed as a separate component 19. While cup-shaped body 13 and threaded tube 14, which has an annular space for a compression spring, are integrally formed with housing 10 and connected thereto via arms 15, clutch feature 18 for non-rotatably restraining drive member 40 is a separate annular component 19 that is axially non-rotatably restrained relative to housing 10. Thus, according to the embodiment of FIGS. 5a and 5b, annular insert member 19 does not have threads 17 as an integral part. As shown in more detail in FIG. 5b, annular insert member 19 includes axially oriented splines 19a on its inner surface for non-rotatably restraining drive member 40. Annular insert member 19 further includes arms or splines 19b on its outer surface for rotatably retaining it within housing 10. Additionally, several hook-like arms 19c are provided to form a snap-fit ​​clip for axially retaining the annular insert member 19 within the housing 10. The annular insert member 19 includes holes or pockets 19d for receiving and securing the hook ends 91 of the drive spring 90. Additionally, the annular insert member 19 has structure that biases the insert members 12, 19 against axial rotation, eliminating free play.

[0060] The reservoir unit body 20 is disposed distally of the housing 10 and is permanently attached thereto. The reservoir unit body may be a transparent or translucent component that is tubular for receiving the reservoir 100. The distal end of the reservoir unit body 20 may be provided with means for attaching a needle arrangement. A removable cap (not shown) is provided to fit over the reservoir unit body 20 and is retained via a clip feature on the housing 10.

[0061] The piston rod 30 is non-rotatably constrained to the drive member 40 via a splined interface. When rotated, the piston rod 30 is forced to move axially relative to the drive member 40 via a threaded interface with the insert 12 of the housing 10. The piston rod 30 is an elongated member having external threads that engage with corresponding threads on the insert 12 of the housing 10. The interface includes at least one longitudinal groove or track and a corresponding protrusion or spline on the drive member 40. The piston rod 30 includes an interface for clip-attaching a bearing 140 to its distal end.

[0062] The drive member 40 is a hollow member that surrounds the piston rod 30 and is disposed within the dose setting member 60. The drive member 40 extends from its interface with the clutch plate 120 to its point of contact with the clutch spring 130. The drive member 40 is axially movable relative to the housing 10, the piston rod 30, and the dose setting member 60 in a distal direction against the bias of the clutch spring 130, and in an opposite proximal direction under the bias of the clutch spring 130.

[0063] A splined tooth interface 18 with the insert 12 prevents rotation of the drive member 40 during dose setting. This interface includes a ring of radially extending external teeth 41 on the distal end of the drive member 40 and corresponding radially extending internal teeth 18 on the housing component 10 (insert 12). When a button 70 is pressed (FIG. 3b), the housing insert splined teeth are disengaged from these drive member teeth, allowing the drive member 40 to rotate relative to the insert and therefore the housing 10. A clutch spring 130 biases the drive member 40 into a position where it engages its teeth 41 and the insert's teeth 18 (FIG. 3a). A further splined tooth interface with the dose setting member 60 is not engaged during dialing, but is engaged when the button 70 is pressed, preventing relative rotation between the drive member 40 and the dose setting member 60 during dispensing. In a preferred embodiment, this interface comprises inwardly facing splines on the inner flange of the dose setting member 60 and a ring of radially extending external splines on the drive member 40. These corresponding splines are arranged on the dose setting member 60 and the drive member 40, respectively, such that axial movement of the drive member 40 relative to the (axially fixed) dose setting member 60 engages or disengages the splines, rotationally coupling or decoupling the drive member 40 and the dose setting member 60.

[0064] A further interface of the drive member 40 includes a ring of ratchet teeth located on the proximal end face of the drive member 40 and a corresponding ring of ratchet teeth on the clutch plate 120 .

[0065] The drive member 40 has a threaded section that provides a helical track for the nut 50. Additionally, there is provided an end of the thread track, or preferably a rotational hard stop, for interaction with a corresponding final dose stop on the nut 50, thus providing a final dose abutment or stop that limits movement of the nut 50 on the driver threads. At least one longitudinal spline on the drive member 40 engages with a corresponding track on the piston rod 30.

[0066] The final dose nut 50 is disposed between the dose setting member 60 and the drive member 40. The final dose nut 50 is non-rotatably constrained to the dose setting member 60 via a splined interface. The final dose nut 50 moves along a helical path relative to the drive member 40 via a threaded interface when relative rotation occurs between the dose setting member 60 and the drive member 40 only during dialing. Alternatively, the nut 50 is splined to the drive member 40 and threadedly engaged with the dose setting member 60. A final dose stop is provided on the nut 50 which engages with a stop on the drive member 40 once a dose corresponding to the remaining dispensable amount of medicament in the reservoir 100 has been set.

[0067] The dose indicator or dose setting member 60 is a tubular element. The dose setting member 60 is rotated during dose setting (via the dose selector 80) and dose correction, as well as during dose dispensing by the torsion spring 90. Together with the gauge element 110, the dose setting member 60 defines a zero position ("rest") and a maximum dose position. The dose setting member 60 can therefore be seen as a dose setting member.

[0068] For manufacturing reasons, the dose setting member 60 in the illustrated embodiment includes a lower dose setting member 60a that is securely fastened to an upper dose setting member 60b during assembly to form the dose setting member 60. The lower dose setting member 60a and the upper dose setting member 60b are separate components solely to simplify mold-making and assembly of the dose setting member 60. Alternatively, the dose setting member 60 may be a single, integral component. The dose setting member 60 is constrained to the housing 10 by a snap engagement that allows rotation but not translational movement. The dose setting member 60 includes an annular recess or groove near its distal end that engages with a corresponding bead on the inner surface of the housing 10. The lower dose setting member 60a is marked with a series of numbers visible through the gauge element 110 and the openings 11a, 11b in the housing 10, indicating the dialed-in dose of medication.

[0069] Furthermore, the dose setting member lower part 60a has a portion with an external thread that engages with the gauge element 110. Both ends of the thread are provided with end stops to limit movement relative to the gauge element 110.

[0070] A clutch feature having a splined annulus form is provided inwardly on the dose setting member upper part 60b for engaging the splines of the button 70 during dose setting and dose correction. A clicker arm is provided on the outer surface of the dose setting member 60 that interacts with the drive member 40 and the gauge member 110 to generate a feedback signal. Additionally, the dose setting member lower part 60a is non-rotatably constrained to the nut 50 and the clutch plate 120 via a splined interface that includes at least one longitudinal spline. Furthermore, the dose setting member lower part 60a includes an interface for mounting a torsion spring 90.

[0071] The button 70, which forms the proximal end of the device, is permanently splined to the dose selector 80. A central stem extends distally from the proximal actuation surface of the button 70. The stem includes a flange carrying splines for engaging with the splines on the dose setting member upper portion 60b. Thus, the central stem is further splined to the dose setting member upper portion 60b via the splines when the button 70 is not depressed, but this spline interface separates when the button 70 is depressed. The button 70 has a discontinuous annular skirt bearing splines. When the button 70 is depressed, the splines on the button 70 engage with the splines on the housing 10, preventing rotation of the button 70 (and thus the dose selector 80) during dispensing. These splines disengage when the button 70 is released, allowing the dose to be dialed in. Additionally, a ring of ratchet teeth is provided on the inside of the button flange for interaction with the clutch plate 120.

[0072] The dose selector 80 is axially constrained relative to the housing 10. The dose selector 80 is rotationally constrained to the button 70 via a splined interface. This splined interface, which has grooves that interact with spline features formed by the annular skirt of the button 70, remains engaged regardless of the axial position of the dose button 70. The dose selector 80, or dose dial grip, is a sleeve-like component with a serrated outer skirt.

[0073] Torsion spring 90 is attached at its distal end by hook 91 to insert 12 and thus to housing 10, and at its other end to dose setting member 60. Torsion spring 90 is disposed within dose setting member 60 and surrounds a distal portion of drive member 40. Torsion spring 90 is pre-wound during assembly so that it applies torque to dose setting member 60 when the mechanism is dialed to zero units. The act of rotating dose selector 80 to set a dose rotates dose setting member 60 relative to housing 10, further loading torsion spring 90.

[0074] The reservoir 100 is housed within the reservoir unit body 20. The reservoir 100 may be a glass ampoule with a removable rubber stopper at its proximal end. The distal end of the reservoir 100 is provided with a pierceable rubber seal held in place by a crimped annular metal band. In the illustrated embodiment, the reservoir 100 is a standard 1.5 ml reservoir. The device is designed to be disposable, in that the reservoir 100 cannot be replaced by the user or a healthcare professional. However, a reusable version of the device can be provided by making the reservoir unit body 20 removable and allowing the piston rod 30 to unwind and the nut 50 to reset.

[0075] The gauge element 110 is constrained to prevent rotation but allows translational movement relative to the housing 10 via a splined interface. The gauge element 110 has a helical feature on its inner surface that engages with a helical threading in the dose setting member 60 so that rotation of the dose setting member 60 causes axial translational movement of the gauge element 110. This helical feature on the gauge element 110 further forms a stop abutment against the ends of the helical cut in the dose setting member 60, limiting the minimum and maximum dose that can be set.

[0076] The gauge element 110 has a generally plate- or strip-like component with a central aperture or window and two flanges extending on either side of the aperture. The flanges are preferably not transparent and therefore shield or cover the dose setting member 60, while the aperture or window allows a portion of the dose setting member lower part 60a to be seen. Additionally, the gauge element 110 has a cam and recess that interact with a clicker arm of the dose setting member 60 upon completion of dose dispensing.

[0077] The clutch plate 120 is an annular component. The clutch plate 120 is splined to the dose setting member 60 via splines. The clutch plate 120 is connected to the drive member 40 via a ratchet interface. The ratchet provides a determined position between the dose setting member 60 and the drive member 40 corresponding to each dosage unit, engaging different inclined tooth angles during clockwise and counterclockwise relative rotation. A clicker arm is provided on the clutch plate 120 to interact with the ratchet function of the button 70.

[0078] The clutch spring 130 is a compression spring. The axial positions of the drive member 40, clutch plate 120, and button 70 are determined by the function of the clutch spring 130, which exerts a proximal force on the drive member 40. This spring force reacts through the drive member 40, clutch plate 120, and button 70, and, when "at rest," further reacts to the housing 10 through the dose selector 80. The spring force ensures that the ratchet interface between the drive member 40 and clutch plate 120 is always engaged. In the "at rest" position, the button splines engage with the dose setting member splines, also ensuring that the drive member teeth engage with the housing 10 teeth.

[0079] The bearing 140 is axially constrained to the piston rod 30 and acts on a bung in the liquid drug reservoir. The bearing 140 is axially clipped onto the piston rod 30 but is free to rotate.

[0080] With the device in its "rest" state as shown in Figures 1 and 3a, the dose setting member 60 is positioned against the gauge element 110 and its zero dose abutment and the button 70 is not pressed. The dose marking "0" on the dose setting member 60 is visible through the window 11b of the housing 10 and the gauge element 110, respectively.

[0081] A torsion spring 90, which has a number of pre-turns applied during assembly of the device, applies a torque to the dose setting member 60, which is prevented from rotating by a zero dose abutment.

[0082] The user selects a variable dose of liquid medication by rotating the dose selector 80 clockwise, thereby producing an identical rotation in the dose setting member 60. Rotation of the dose setting member 60 causes a load on the torsion spring 90, increasing the energy stored therein. As the dose setting member 60 rotates, the gauge element 110 translates axially due to its threaded engagement, thereby indicating the value of the dialed-in dose. The gauge element 110 has flanges on either side of a window area that covers the numbers printed on the dose setting member 60 adjacent to the dialed-in dose to ensure that only the set dose number is visible to the user.

[0083] A particular feature of the present disclosure is the inclusion of a visual feedback function in addition to the discrete dose number indications typical of this type of device. The distal end of the gauge element 110 produces a sliding scale through a small window 11a in the housing 10. Alternatively, the sliding scale can be formed using a separate component that engages with the dose setting member 60 at different helical tracks.

[0084] When a dose is set by the user, the gauge element 110 translates axially, a distance traveled proportional to the size of the set dose. This feature provides clear feedback to the user regarding the approximate size of the dose setting. Because the dispensing rate of an auto-injector mechanism may be higher than that of a manual injector device, the numeric dose reading may not be readable during dispensing. The gauge feature provides feedback to the user regarding the progress of dispensing during dispensing without the need to read the dose number itself. For example, the gauge reading could be formed by an opaque element in the gauge element 110, revealing a contrasting colored component underneath. Alternatively, the revealing element could be printed with the approximate dose number or other indicator that provides more precise resolution. Additionally, the gauge reading simulates the action of a syringe during dose setting and dispensing.

[0085] The drive member 40 sets the dose by engaging its spline teeth with the teeth of the housing 10 and is prevented from rotating when the dose setting member 60 rotates. Therefore, relative rotation must occur between the clutch plate 120 and the drive member 40 via the ratchet interface.

[0086] The user torque required to rotate the dose selector 80 is the sum of the torque required to wind up the torsion spring 90 and the torque required to loosen the ratchet interface. The clutch spring 130 is designed to provide an axial force at the ratchet interface, urging the clutch plate 120 toward the drive member 40. This axial load acts to maintain the ratchet teeth engagement between the clutch plate 120 and the drive member 40. The torque required to loosen the ratchet in the dose setting direction is a function of the axial load applied by the clutch spring 130, the clockwise inclination angle of the ratchet teeth, the coefficient of friction between the mating surfaces, and the average radius of the ratchet interface.

[0087] When the user rotates the dose selector 80 enough to increment the mechanism by one increment, the dose setting member 60 rotates relative to the drive member 40 by one ratchet tooth, at which point the ratchet tooth re-engages into the next detent position. An audible click is produced by the ratchet re-engagement and tactile feedback is provided by the change in the required torque input.

[0088] Relative rotation is possible between the dose setting member 60 and the drive member 40. This relative rotation also moves the final dose nut 50 along its threaded path towards the final dose abutment of the drive member 40.

[0089] In the absence of user torque applied to the dose selector 80, the dose setting member 60 is prevented from rotating back under the torque applied by the torsion spring 90 only by the ratchet interface between the clutch plate 120 and the drive member 40. The torque required to loosen the ratchet in the counterclockwise direction is a function of the axial load applied by the clutch spring 130, the counterclockwise tilt angle of the ratchet, the coefficient of friction between the mating surfaces, and the average radius of the ratchet mechanism. The torque required to loosen the ratchet must be greater than the torque applied by the torsion spring 90 to the dose setting member 60 (and therefore the clutch plate 120). The ratchet tilt angle therefore increases in the counterclockwise direction to ensure this is the case, and to ensure that the dial-up torque is as small as possible.

[0090] The user may now choose to increase the selected dose by continuing to rotate the dose selector 80 in a clockwise direction. The process of loosening the ratchet interface between the dose setting member 60 and the drive member 40 is repeated for each dose increment. Additional energy is stored in the torsion spring 90 for each dose increment, and audible and tactile feedback is provided for each increment dialed in by the re-engagement of the ratchet teeth. The torque required to rotate the dose selector 80 increases as the torque required to wind up the torsion spring 90 increases. Therefore, the torque required to loosen the ratchet in a counterclockwise direction must be greater than the torque applied to the dose setting member 60 by the torsion spring 90 when the maximum dose is reached.

[0091] If the user continues to increase the selected dose until the maximum dose limit is reached, the dose setting member 60 engages its maximum dose abutment on the maximum dose abutment of the gauge element 110. This prevents further rotation of the dose setting member 60, the clutch plate 120 and the dose selector 80.

[0092] During dose selection, depending on the number of unit increments of drug already delivered by the mechanism, the final dose nut 50 can bring a final dose abutment into contact with a stop surface on the drive member 40. The abutment prevents further relative rotation between the dose setting member 60 and the drive member 40, thus limiting the dose that can be selected. The position of the final dose nut 50 is determined by the total number of relative rotations between the dose setting member 60 and the drive member 40, which occurs each time the user sets a dose.

[0093] With the mechanism in a dose selected state, the user can deselect any number of increments from that dose. Deselecting a dose is accomplished by the user rotating the dose selector 80 counterclockwise. The torque applied to the dose selector 80 by the user, when combined with the torque applied by the torsion spring 90, is sufficient to loosen the ratchet interface between the clutch plate 120 and the drive member 40 in a counterclockwise direction. Loosening the ratchet causes a counterclockwise rotation of the dose setting member 60 (via the clutch plate 120), returning the dose setting member 60 to the zero dose position and unwinding the torsion spring 90. The relative rotation between the dose setting member 60 and the drive member 40 causes the final dose nut 50 to move back along its helical path, away from the final dose abutment.

[0094] With the mechanism in a dose selected state, the user can activate the mechanism to begin dose delivery, which is initiated by the user depressing button 70 axially in the distal direction (FIG. 3b).

[0095] When the button 70 is depressed, the splines between the button 70 and the dose setting member 60 disengage, rotatably decoupling the button 70 and dose selector 80 from the delivery mechanism, i.e., from the dose setting member 60, gauge element 110 and torsion spring 90. The splines on the button 70 engage with splines on the housing 10, preventing rotation of the button 70 (and therefore the dose selector 80) during dispensing. Because the button 70 remains stationary during dispensing, it is used in a dispensing clicker mechanism. The stop feature on the housing 10 limits the axial movement of the button 70, reducing the risk of reacting to erroneous axial loads applied by the user and damaging internal components.

[0096] The clutch plate 120 and drive member 40 move axially with the button 70. This engages the splined tooth interface between the drive member 40 and the dose setting member 60, preventing relative rotation between the drive member 40 and the dose setting member 60 during dispensing. The splined tooth interface 18, 41 between the drive member 40 and the housing insert 12 disengages, so that the drive member 40 can now rotate, driven by the torsion spring 90 via the dose setting member 60 and the clutch plate 120.

[0097] Rotation of the drive member 40 rotates the piston rod 30 due to its splined engagement, which in turn advances the piston rod 30 due to its threaded engagement into the housing 10. Rotation of the dose setting member 60 also axially traverses the gauge element 110 back to its zero position, whereby the zero dose abutment stops the mechanism.

[0098] Tactile feedback during dose dispensing is provided via a flexible cantilever clicker arm integrated into the clutch plate 120. This arm radially interfaces with a ratchet mechanism on the inner surface of the button 70, whereby the spacing of the ratchet teeth corresponds to the rotation of the dose setting member 60 required to dispense a single increment. During dispensing, as the dose setting member 60 rotates and the button 70 is rotatably coupled to the housing 10, the ratchet feature engages the clicker arm to produce an audible click with each dose increment delivered.

[0099] Dose delivery continues via the above mechanical interaction while the user continues to depress button 70. When the user releases button 70, clutch spring 130 returns drive member 40 (together with clutch plate 120 and button 70) to its "rest" position, engaging the splines between drive member 40 and housing 10, preventing further rotation and stopping dose delivery.

[0100] During dose delivery, the drive member 40 and the dose setting member 60 rotate together, resulting in no relative movement of the final dose nut 50. The final dose nut 50 therefore moves axially relative to the drive member 40 only during dial setting.

[0101] Once dose delivery has been stopped by the dose setting member 60 returning to the zero dose abutment, the user can release the button 70, which will re-engage the spline teeth between the drive member 40 and the housing 10. The mechanism is now returned to its "rest" state.

[0102] At the end of dose dispensing, further audible feedback is provided in the form of a "click" different from the "click" provided during dispensing, informing the user that the device has returned to its zero position through the interaction of the clicker arm of the dose setting member 60 with the ramp, cam and recess of the gauge element 110 of the drive member 40. This embodiment ensures that feedback is only produced at the end of dose delivery and not when the device is dialed back to or away from the zero position.

[0103] 6a, 6b, 7a and 7b show schematic cross-sectional views of the area of ​​the mechanism unit for various alternative embodiments of the drug delivery device, including the piston rod 30 and the drive member 40 together with the clutch spring 130. These embodiments allow for precise adjustment of the position of the piston rod 30 relative to the housing 10 before final assembly of the drug delivery device. The device may be as further described above. Thus, the configurations described in FIGS. 1 to 5 can be used for the embodiments described below. The drug delivery device may be disposable or reusable. In the embodiments of Figures 6a, 6b, 7a, 7b, 9a, 9b, 9c, 9d, 10a, 10b, 10c, and 10d, the mechanism unit includes a housing 10, a piston rod 30 that is movably held within the housing 10, and a dose setting and driving mechanism configured to perform a dose setting operation of setting a dose to be delivered, and a dose setting operation of delivering the set dose by transmitting a delivery force to the piston rod 30 to drive the piston rod 30 distally relative to the housing 10 in a dose delivery operation.

[0104] As used herein, the terms "distal" and "proximal" can refer to opposite axial directions or ends. "Distal" can refer to the direction toward the dosing end or the end of the reservoir 100, reservoir unit body 20, or drug delivery device component that is or should be located closest to the dosing end of the drug delivery device. "Proximal" can refer to the direction away from the dosing end or the end that is or should be located further away from the reservoir 100, reservoir unit body 20, or drug delivery device dosing end. Additionally, the distal direction can be away from the proximal end. The proximal direction can be away from the distal end.

[0105] The dose setting and drive mechanism includes a drive member 40 and a clutch mechanism. In contrast to the configurations described above in which the drive member was one piece, the drive member 40 in the embodiments of Figures 6a, 6b, 7a, 7b, 9a, 9b, 9c, 9d, 10a, 10b, 10c, and 10d is a two-part component comprising a first drive member 40a and a second drive member 40b. The piston rod 30 is movable relative to the housing 10, e.g., is movably held within the housing 10 (not shown in Figures 6a, 6b, 7a, 7b, 9a, 9b, 9c, 9d, 10a, 10b, 10c, and 10d). The first drive member 40a directly mechanically cooperates with the piston rod 30 via a lock 44 (shown in FIGS. 6a, 6b, 7a, 7b, 10a, and 10b) or a thread guide 45 (shown in FIGS. 9a, 9b, 9c, and 9d) to transmit force to the piston rod 30; the lock 44 and thread guide 45 may be integral parts of the first drive member 40a. The first drive member 40a is axially fixed and rotatable relative to the housing 10; rotation of the first drive member 40a relative to the housing 10 in a delivery direction moves the piston rod 30 distally, and rotation in the opposite direction moves the piston rod 30 proximally. The second drive member 40b is mechanically coupled, preferably directly, to the first drive member 40a and is arranged to transmit a delivery force to the first drive member 40a. As shown in the embodiments of Figures 6a, 6b, 7a, 7b, 10a, and 10b, the first drive member 40a is splined to the piston rod, which is threadedly connected to the housing, or as shown in Figures 9a, 9b, 9c, and 9d, the first drive member 40a is threadedly connected to the piston rod, which is splined to the housing.

[0106] The clutch mechanism includes a clutch spring 130. Because a distal end of the clutch spring 130 is on the first drive member 40a and a proximal end of the clutch spring 130 is on the second drive member 40b, distal axial movement of the second drive member 40b relative to the first drive member 40a can occur only against the resistance of the spring force of the clutch spring 130. The clutch mechanism has at least two different states: a delivery state (see FIGS. 6b, 7b, 9a, and 10b) in which the clutch spring 130 is compressed, and a set state (see FIGS. 6a, 7a, 9b, and 10a) in which the clutch spring 130 is less compressed than in the delivery state.

[0107] In the set state, the second drive member 40b is fixed to be non-rotatable relative to the housing 10, at least against rotation in the delivery direction. The second drive member 40b is fixed to be non-rotatable relative to the housing 10, similar to the integrated drive member 40 shown in FIGS. 1-5. However, it is also contemplated that in the set state, the second drive member 40b is fixed to be non-rotatable relative to the housing 10 against rotation in the delivery direction and in the direction opposite to the delivery direction. The second drive member 40b is rotatable in the delivery direction relative to the housing 10 in the delivery state, and the first drive member 40a is rotatable in at least the delivery direction relative to the second drive member 40b and the housing 10 in the set state, and the second drive member 40b is locked to be non-rotatable relative to the first drive member 40a in the delivery state, at least against rotation in the delivery direction of the second drive member 40b relative to the first drive member 40a. However, it is also conceivable that in the delivery state, the second drive member 40b is locked non-rotatably relative to the first drive member 40a, preventing rotation of the second drive member 40b relative to the first drive member 40a in the delivery direction and in the direction opposite to the delivery direction.

[0108] The mechanism unit is configured to be coupled to a reservoir unit including a reservoir 100 and a reservoir unit body 20 for assembling the two units. In a set state, the first drive member 40a is accessible from the exterior of the housing 10 for manipulation so that the position of the piston rod 30 relative to the housing 10 can be adjusted by rotating the first drive member 40a before the mechanism unit and the reservoir unit are coupled. This accessibility may be via either or both of the distal and proximal ends of the housing 10. However, it is also conceivable that the first drive member 40a is accessible from the exterior of the housing 10 after the mechanism unit and the reservoir unit are coupled, before the drug delivery device is fully assembled. In this case, the first drive member 40a is accessible from the proximal end of the housing 10 through an opening that is closed by a button 70 during final assembly of the drug delivery device. It goes without saying that this opening can also be used to manipulate the first drive member 40a before the mechanism unit is coupled to the reservoir unit.

[0109] In the embodiments of Figures 6a, 6b, 7a, 7b, 9a, 9b, 9c, 9d, 10a, 10b, 10c, and 10d, the second drive member 40b is axially movable, e.g., distally, relative to the first drive member 40a and the housing 10 to switch between the set state shown in Figures 6a, 7a, 9b, and 10a and the delivery state shown in Figures 6b, 7b, 9a, and 10b. Furthermore, the first drive member 40a is fixed against proximal and distal movement relative to the housing 10 in the set state and the delivery state.

[0110] The first drive member 40a is engaged with the piston rod 30, which is engaged with the housing 10. In the embodiment of Figures 6a, 6b, 7a, 7b, 10a, and 10b, the first drive member 40a is directly splined to the piston rod 30 by a lock 44, and the piston rod 30 is threadably engaged with the housing 10. In this case, rotational movement of the first drive member 40a relative to the piston rod 30 is not possible in the set and delivery states.

[0111] As shown in Figures 6a, 6b, 7a, and 7b, the first drive member 40a includes a first locking feature 42, and the second drive member 40b includes a second locking feature 43. The first locking feature 42 is rotationally and axially immovable relative to the first drive member 40a, and the second locking feature 43 is rotationally and axially immovable relative to the second drive member 40b. The first locking feature 42 may be an integral part of the first drive member 40a, and the second locking feature 43 may be an integral part of the second drive member 40b. As shown in Figures 6b and 7b, the first locking feature 42 engages with the second locking feature 43 in the delivery state.

[0112] Figures 6a and 6b show an embodiment of the mechanism unit, in the set state the first locking feature 42 and the second locking feature 43 are disengaged.

[0113] FIG. 6a shows the mechanism unit in a set state. In this state, the clutch spring 130 is relaxed, and the first drive member 40a is not engaged with the second drive member 40b. Because the first locking feature 42 and the second locking feature 43 are disengaged, the first drive member 40a and the piston rod 30 can rotate relative to the second drive member 40b in both the delivery direction and the counter-delivery direction. This allows the first drive member 40a to axially move the piston rod 30 in both the proximal and distal directions, independently adjusting the distance between the proximal end of the bung and the distal end of the piston rod 30. In this state, the second drive member 40b cannot rotate relative to the housing 10.

[0114] FIG. 6b shows the mechanism unit according to the same embodiment as shown in FIG. 6a in a delivery state. In this state, the second drive member 40b is axially displaced distally by compressing the button 70. This compresses the clutch spring 130, engaging the first locking feature 42 with the second locking feature 43. The resulting coupling between the first locking feature 42 and the second locking feature 43 immobilizes the first drive member 40a relative to the second drive member 40b in the delivery direction and the direction opposite to the delivery direction. Thus, rotation of the second drive member 40b leads to rotation of the first drive member 40a, which in turn displaces the piston rod 30 axially distally to dispense the drug from the reservoir 100. After the button 70 is pressed, the spring force of the clutch spring 130 returns the second drive member 40b to its original position in the set mode.

[0115] In the embodiment shown in Figures 6a and 6b, the first locking feature 42 is designed as a circumferential outer ring on the outer peripheral surface of the proximal end of the first drive member 40a, and the second locking feature 43 is arranged as a circumferential inner ring on the inner peripheral surface of the distal end of the second drive member 40b. The two rings have complementary locking wedges. In the setting mode, these locking wedges are axially pressed against each other so that relative rotational movement between the first locking feature 42 and the second locking feature 43 is not possible.

[0116] The locking wedges of the second locking feature 43 are tapered at their distal ends. Additionally or alternatively, the locking wedges of the first locking feature 42 are tapered at their proximal ends. The taper is designed to facilitate insertion of the second locking feature 43 into the first locking feature 42 during transition from the setup state to the delivery state.

[0117] The embodiment shown in Figures 6a and 6b is particularly advantageous as the position of the piston rod 30 can be varied axially in the distal and proximal directions in a set state.

[0118] Figures 7a and 7b show an alternative embodiment of the mechanism unit, in which the first locking feature 42 is engaged with the second locking feature 43 in the set state (see Figure 7a) and in the delivery state (see Figure 7b).

[0119] In this case, the first locking feature 42 and the second locking feature 43 are configured such that, when the first locking feature 42 engages with the second locking feature 43, the first locking feature 42 is rotatable relative to the second locking feature 43 in the delivery direction and is fixed to be non-rotatable relative to the second locking feature 43 in the opposite direction to the delivery direction. The first locking feature 42 is designed as a circumferential outer ring on the outer peripheral surface of the proximal end of the first drive member 40a, and the second locking feature 43 is arranged as a circumferential inner ring on the inner peripheral surface of the distal end of the second drive member 40b. The two rings have complementary serrated wedges (see FIG. 8 ) that allow the first drive member 40a to rotate in the delivery direction relative to the second drive member 40b and prevent the first drive member 40a from rotating in the opposite direction to the delivery direction relative to the second drive member 40b in both the setup mode and the delivery mode.

[0120] As shown in FIG. 8 , the first locking feature 42 and / or the second locking feature 43 are elastically configured so that the serrated wedges of the first locking feature 42 can slide over the serrated wedges of the second locking feature 43 when the first locking feature 42 moves in the delivery direction D. However, in this case, the serrated wedges of the first locking feature 42 cannot slide over the serrated wedges of the second locking feature 43 in the opposite direction of the delivery direction D. As a result, in this case, movement of the serrated wedges of the second locking feature 43 of the second drive member 40b in the delivery direction D necessarily results in movement of the serrated wedges of the first locking feature 42 of the first drive member 40a in the delivery direction D. It should be noted that other interlocking mechanisms between the first locking feature 42 and the second locking feature 43 are also possible to achieve the above effect. For example, the use of other ratchet connections or pawls is conceivable.

[0121] Due to the sawtooth coupling, it is not necessary to disengage the first drive member 40a from the second drive member 40b in the set mode in order to axially displace the piston rod 30 distally by rotational movement of the first drive member 40a, as shown in Figures 7a, 7b, and 8. Thus, in contrast to the embodiment of Figures 6a and 6b, the insertion step of the first locking feature 42 relative to the second locking feature 43 during the transition from the set mode to the delivery mode is avoided. Furthermore, after setting the desired distance between the proximal end of the bung and the distal end of the piston rod 30, the sawtooth coupling prevents proximal axial displacement of the piston rod 30, since rotational movement of the first drive member 40a in the direction opposite the delivery direction is not possible.

[0122] However, it should be noted that it is also conceivable that the first locking feature 40a and the second locking feature 40b of the embodiment of Figures 6a and 6b could be made as sawtooth connections.

[0123] Similar to the embodiment of Figures 6a and 6b, in the embodiment of Figures 7a and 7b, the second drive member 40b is non-rotatably locked relative to the housing 10 in the set state and is rotatably movable in the delivery state.

[0124] Figures 9a, 9b, 9c, 9d, and 10a, 10b, 10c, 10d respectively show a further embodiment of a two-part drive member 40 of a mechanism unit for a drug delivery device according to the present invention, where Figures 9a, 9b, 10a, and 10b show longitudinal cross-sectional views, and Figures 9c, 9d, 10c, and 10d show cross-sectional views of the drive member 40. The drug delivery device may be as further described above. Thus, the configurations described in Figures 1-5 can be used for the embodiments described below. The drive member 40 includes a first drive member 40a and a second drive member 40b, where the first drive member 40a includes a first locking feature 42 and the second drive member 40b includes a second locking feature 43. The first locking feature 42 is rotationally and axially immovable relative to the first drive member 40a, and the second locking feature 43 is rotationally and axially immovable relative to the second drive member 40b. The first locking feature 42 may be an integral part of the first drive member 40a, and the second locking feature 43 may be an integral part of the second drive member 40b. The first locking feature 42 engages with the second locking feature 43 in a delivery state (see FIGS. 9a and 10b) and a set state (see FIGS. 9b and 10a). The embodiments of Figures 9a, 9b, 9c, 9d and 10a, 10b, 10c, 10d differ only in that the first drive member 40a in Figures 9a, 9b, 9c, and 9d is splined to the piston rod 30, which is threadedly connected to the housing 10, and the first drive member 40a in Figures 10a, 10b, 10c, and 10d is threadedly connected to the piston rod 30, which is splined to the housing 10.

[0125] FIG. 11 shows the outer surface of the first drive member 40a of the embodiment shown in FIGS. 9a, 9b, 9c, 9d, and 10a, 10b, 10c, and 10d. The outer surface includes a first locking feature 42, which is designed as at least one tooth or rib having a high region, i.e., first locking portion 42a, and a low region, i.e., second locking portion 42b. The high region may protrude radially beyond the low region. The first locking feature may extend axially along the first drive member 40a. Specifically, the first locking feature is axially oriented. The first locking portion 42a is located distally of the shaft ahead of the second locking portion 42b. That is, the first locking portion is disposed distally relative to the second locking portion. The first locking portion 42a engages with the second locking feature 43 in the delivery state, and the second locking portion 42b engages with the second locking feature 43 in the set state.

[0126] 9c and 10d, rotation of the first drive member 40a relative to the second drive member 40b is not possible in the delivery state because the first locking portion 42a cannot rotate relative to the second locking feature 43. This is achieved by selecting the height of the first locking portion 42a such that the recess formed by the second locking feature 43 is almost completely filled by the first locking portion 42a.

[0127] As shown in FIGS. 9d and 10c, the height of the second locking portion 42b is such that the recess of the second locking feature 43 is only partially filled by the second locking portion 42b. Therefore, in the setting mode, the second locking portion 42b can slide on the second locking feature 43 using an external force. Therefore, the first drive member 40a can rotate relative to the second drive member 40b in the setting mode. However, due to the height of the second locking portion 42b, the second locking portion 42b preferably cannot slide on the second locking feature 43 without the aid of an external force. This prevents the loss of settings already made in the setting state. Furthermore, sliding the second locking portion 42b on the second locking feature 43 can generate audible or tactile feedback during the adjustment process.

[0128] In the embodiments of Figures 6a, 6b, 7a, 7b, 9a, 9b, 9c, 9d, 10a, 10b, 10c, and 10d, the first locking feature 42 and the second locking feature 43 are designed so that when the first locking feature 42 engages with the second locking feature 43, the first drive member 40a occupies one of several stable positions relative to the second drive member 40b. Preferably, these stable positions are defined by the relative distance between immediately adjacent locking wedges. The angular distance between the stable positions is adjusted to an angle at which the user must rotate the dose setting member to set the minimum dose to be delivered by the drug delivery device. This dose may correspond to a one-unit increment. Furthermore, the distance between the stable positions is such that movement of the first drive member 40a relative to the second drive member 40b from one of the stable positions to the next immediately adjacent stable position results in an axial movement of the piston rod 30 corresponding to the axial movement of the piston rod 30 during delivery of at most one unit increment of the dose. It is also conceivable to design the locking features 42 and 43 such that movement of the first drive member 40a relative to the second drive member 40b from one of the stable positions to the next immediately adjacent stable position results in an axial movement of the piston rod 30 corresponding to the axial movement of the piston rod 30 during delivery of less than one unit increment, for example, ½ or ¼ unit increment.

[0129] When the first locking feature 42 is not engaged with the second locking feature 43 in the set mode, as in the embodiment of Figures 6a and 6b, the transition from the set state to the delivery state should ensure that there is no interference with the locking wedges of the locking features 42 and 43, which could prevent distal axial displacement of the second drive member 40b. Therefore, it may be advantageous to design the first drive member 40a so that, after rotational movement relative to the second drive member 40b, the first drive member 40a rests only in a position relative to the second drive member 40b that corresponds to one of the stable positions, i.e., a position where the locking wedges can reliably interlock. For example, the first drive member 40a can only rotate incrementally relative to the second drive member 40b.

[0130] In the embodiments of Figures 6a, 6b, 7a, 7b, 9a, 9b, 9c, 9d, 10a, 10b, 10c, and 10d, the dose setting and driving mechanism includes a dose setting member 60 that is movable relative to the housing 10 in a set state from an initial position to a dose setting position to set a dose of medication. The dose setting member 60 is non-rotatably constrained relative to the second drive member 40b in the delivery state and is rotatable relative to the second drive member 40b in the set state. The first drive member 40a is non-rotatably constrained relative to the dose setting member 60 and the second drive member 40b in the direction opposite to the delivery direction in the delivery state. Furthermore, the first drive member 40a may be rotatable in the delivery direction relative to the dose setting member 60 and the second drive member 40b in the delivery state. The first drive member 40a may be rotatable in the delivery direction relative to the dose setting member 60 and the second drive member 40b in the set state. Furthermore, the first drive member 40a may be rotatable in the delivery direction and in the counter-delivery direction relative to the dose setting member 60 and the second drive member 40b in the set state.

[0131] The manufacture of a drug delivery device including one of the embodiments of Figures 6a, 6b, 7a, 7b, 9a, 9b, 9c, 9d, 10a, 10b, 10c, and 10d begins with the provision of a reservoir unit including a reservoir 100 containing a drug, a stopper being movably held within the reservoir 100, the reservoir 100 being held within a reservoir unit body 20, and a mechanical unit being provided.

[0132] Then, a bung position of the bung relative to the reservoir unit body 20 is determined. Additionally, a desired piston rod position of the piston rod 30 relative to the housing 10 is determined based on the determined bung position. The desired piston rod position is determined such that the piston rod 30 and the bung will be positioned at a predetermined distance from each other when the mechanism unit and the reservoir unit are coupled. Furthermore, a specific displacement distance that the piston rod 30 must be displaced distally relative to the housing 10 to achieve the desired piston rod position is determined. The predetermined distance between the piston rod 30 and the bung is a distance that allows the exact dose set by the user to be delivered upon the first actuation of the drug delivery device after assembly of the device.

[0133] Subsequently, in the setting state of the mechanism unit, the first driving member 40a rotates relative to the second driving member 40b, displacing the piston rod 30 by a specific displacement distance relative to the housing. Finally, the reservoir unit and the mechanism unit are coupled to each other.

[0134] However, it should be noted that the rotation of the first drive member 40a relative to the second drive member 40b to displace the piston rod 30 a certain displacement distance relative to the housing can also be performed after the reservoir unit and the mechanism unit are coupled to each other but before the drug delivery device is fully assembled. As mentioned above, in this case the first drive member 40a is accessible from the proximal end of the housing 10 through an opening that is closed by the button 70 after the appropriate piston rod position is reached during final assembly of the drug delivery device.

[0135] The terms "drug" or "medicament" are used interchangeably herein to describe a pharmaceutical formulation containing one or more active pharmaceutical ingredients or pharmaceutically acceptable salts or solvates thereof, and optionally a pharmaceutically acceptable carrier. An active pharmaceutical ingredient ("API"), in its broadest sense, is a chemical structure that has a biological effect on humans or animals. In pharmacology, drugs or medications are used to treat, cure, prevent, or diagnose disease or otherwise improve physical or mental well-being. Drugs or medications can be used for a limited duration or periodically for chronic disorders.

[0136] As described below, drugs or pharmaceutical agents may contain at least one API or a combination thereof in various types of formulations for the treatment of one or more diseases. Examples of APIs include small molecules with a molecular weight of 500 Da or less, polypeptides, peptides, and proteins (e.g., hormones, growth factors, antibodies, antibody fragments, and enzymes), carbohydrates and polysaccharides, as well as nucleic acids, double-stranded or single-stranded DNA (including naked and cDNA), RNA, antisense nucleic acids such as antisense DNA and RNA, small interfering RNA (siRNA), ribozymes, genes, and oligonucleotides. Nucleic acids can be incorporated into molecular delivery systems such as vectors, plasmids, or liposomes. Mixtures of one or more drugs are also contemplated.

[0137] The drug or agent can be contained in a primary package or "drug container" adapted for use in a drug delivery device. The drug container can be, for example, a reservoir, syringe, reservoir, or other rigid or flexible vessel configured to provide a chamber suitable for storage (e.g., short-term or long-term storage) of one or more drugs. For example, in some cases, the chamber can be designed to store the drug for at least one day (e.g., from one day to at least 30 days). In some cases, the chamber can be designed to store the drug for about one month to about two years. Storage can be at room temperature (e.g., about 20°C) or at refrigerated temperatures (e.g., from about -4°C to about 4°C). In some cases, the drug container can be or include a dual-chamber reservoir configured to separately store two or more components of a pharmaceutical formulation to be administered (e.g., an API and a diluent, or two different drugs), one in each chamber. In such cases, the two chambers of the dual-chamber reservoir can be configured to allow mixing between the two or more components prior to and / or during administration to the human or animal body. For example, the two chambers can be configured to be in fluid communication with each other (e.g., via a conduit between the two chambers) and to allow mixing of the two components by a user, if desired, prior to administration. Alternatively or additionally, the two chambers can be configured to allow mixing upon administration of the components to the human or animal body.

[0138] The drugs or agents contained in the drug delivery devices described herein can be used for the treatment and / or prevention of many different types of medical disorders. Examples of disorders include diabetes or complications associated with diabetes, such as diabetic retinopathy, and thromboembolic disorders, such as deep vein thromboembolism (DVT) or pulmonary embolism. Further examples of disorders include acute coronary syndrome (ACS), angina, myocardial infarction, cancer, macular degeneration, inflammation, hay fever, atherosclerosis, and / or rheumatoid arthritis. Examples of APIs and drugs are those listed in handbooks such as Rote Liste 2014 (e.g., but not limited to, Main Group 12 (antidiabetic agents) or 86 (oncology agents)) and the Merck Index, 15th edition.

[0139] Examples of APIs for the treatment and / or prevention of type 1 or type 2 diabetes or complications associated with type 1 or type 2 diabetes include insulin, e.g., human insulin, or a human insulin analog or derivative; glucagon-like peptide (GLP-1), a GLP-1 analog or GLP-1 receptor agonist, or an analog or derivative thereof; a dipeptidyl peptidase-4 (DPP4) inhibitor; or a pharmaceutically acceptable salt or solvate thereof, or any mixture thereof. As used herein, the terms "analog" and "derivative" refer to a polypeptide having a molecular structure that is formally derivable from the structure of a naturally occurring peptide, e.g., the structure of human insulin, by deletion and / or replacement of at least one amino acid residue present in the naturally occurring peptide and / or by addition of at least one amino acid residue. The added and / or replaced amino acid residue can be either a codable amino acid residue, another naturally occurring residue, or a purely synthetic amino acid residue. Insulin analogs are also referred to as "insulin receptor ligands." In particular, the term "derivative" refers to a polypeptide having a molecular structure formally derivable from the structure of a naturally occurring peptide, e.g., the molecular structure of human insulin in which one or more organic substituents (e.g., fatty acids) are attached to one or more of the amino acids. Optionally, one or more amino acids present in the naturally occurring peptide are deleted and / or replaced by other amino acids, including non-encodable amino acids, or amino acids, including non-encodable ones, are added to the naturally occurring peptide.

[0140] Examples of insulin analogues are Gly(A21), Arg(B31), Arg(B32) human insulin (insulin glargine); Lys(B3), Glu(B29) human insulin (insulin glulisine); Lys(B28), Pro(B29) human insulin (insulin lispro); Asp(B28) human insulin (insulin aspart); human insulin in which the proline at position B28 is replaced by Asp, Lys, Leu, Val or Ala and the Lys at position B29 may be replaced by Pro; Ala(B26) human insulin; Des(B28-B30) human insulin; Des(B27) human insulin and Des(B30) human insulin.

[0141] Examples of insulin derivatives are, for example, B29-N-myristoyl-des(B30) human insulin, Lys(B29)(N-tetradecanoyl)-des(B30) human insulin (insulin detemir, Levemir®); B29-N-palmitoyl-des(B30) human insulin; B29-N-myristoyl human insulin; B29-N-palmitoyl human insulin; B28-N-myristoylLysB28ProB29 human insulin; B28-N-palmitoyl-LysB28ProB29 human insulin; B30-N-myristoyl-ThrB29LysB30 human insulin. B30-N-palmitoyl-ThrB29LysB30 human insulin; B29-N-(N-palmitoyl-gamma-glutamyl)-des(B30) human insulin, B29-N-omega-carboxypentadecanoyl-gamma-L-glutamyl-des(B30) human insulin (insulin degludec, Tresiba®); B29-N-(N-lithocholyl-gamma-glutamyl)-des(B30) human insulin; B29-N-(ω-carboxyheptadecanoyl)-des(B30) human insulin and B29-N-(ω-carboxyheptadecanoyl) human insulin.

[0142] Examples of GLP-1, GLP-1 analogs and GLP-1 receptor agonists are, for example, lixisenatide (Lyxumia®), exenatide (exendin-4, Byetta®, Bydureon®, a 39 amino acid peptide produced by the salivary glands of the flathead monster), liraglutide (Victoza®), semaglutide, taspoglutide, albiglutide (Syncria®), dulaglutide (Trulicity®), rexendin -4, CJC-1134-PC, PB-1023, TTP-054, langrenatide / HM-11260C, CM-3, GLP-1 Erigen, ORMD-0901, NN-9924, NN-9926, NN-9927, nodexene, Viadol-GLP-1, CVX-096, ZYOG-1, ZYD-1, GSK-2374697, DA-3091, MAR-701, MAR709, ZP-2929, ZP-3022, TT-401, BHM-034, MOD-6030, CAM-2036, DA-15864, ARI-2651, ARI-2255, exenatide-XTEN, and glucagon-Xten.

[0143] An example of an oligonucleotide is, for example, mipomersen sodium (Kynamro®), a cholesterol-lowering antisense therapeutic for the treatment of familial hypercholesterolemia.

[0144] Examples of DPP4 inhibitors are vidagliptin, sitagliptin, denagliptin, saxagliptin, and berberine.

[0145] Examples of hormones include pituitary or hypothalamic hormones or regulatory active peptides and their antagonists, such as gonadotropins (follitropin, lutropin, chorion gonadotropin, menotropin), somatropine (somatropin), desmopressin, terlipressin, gonadorelin, triptorelin, leuprorelin, buserelin, nafarelin, and goserelin.

[0146] Examples of polysaccharides include glycosaminoglycans, hyaluronic acid, heparin, low molecular weight heparin or ultra-low molecular weight heparin or their derivatives, or sulfated polysaccharides, such as the polysulfated forms of the above-mentioned polysaccharides, and / or their pharmaceutically acceptable salts.An example of a pharmaceutically acceptable salt of polysulfated low molecular weight heparin is enoxaparin sodium.An example of a hyaluronic acid derivative is Hylan G-F20 (Synvisc®), sodium hyaluronate.

[0147] As used herein, the term "antibody" refers to an immunoglobulin molecule or an antigen-binding portion thereof. Examples of antigen-binding portions of immunoglobulin molecules include F(ab) and F(ab')2 fragments that retain antigen-binding ability. An antibody can be a polyclonal antibody, a monoclonal antibody, a recombinant antibody, a chimeric antibody, a deimmunized or humanized antibody, a fully human antibody, a non-human (e.g., murine) antibody, or a single-chain antibody. In some embodiments, an antibody has effector function and is capable of fixing complement. In some embodiments, an antibody has reduced or no binding ability to Fc receptors. For example, an antibody can be an isotype or subtype, antibody fragment, or mutant that does not support Fc receptor binding, e.g., with a mutation or deletion of the Fc receptor binding region. The term antibody also includes antigen-binding molecules based on tetravalent bispecific tandem immunoglobulins (TBTIs) and / or dual variable region antibody-like binding proteins (CODVs) with a crossover binding region orientation.

[0148] The term "fragment" or "antibody fragment" refers to a polypeptide (e.g., an antibody heavy and / or light chain polypeptide) derived from an antibody polypeptide molecule that does not include the full-length antibody polypeptide but comprises at least a portion of the full-length antibody polypeptide that is still capable of binding to antigen. Antibody fragments can include truncated portions of a full-length antibody polypeptide, but the term is not limited to such truncated fragments. Antibody fragments useful in the present disclosure include, for example, Fab fragments, F(ab')2 fragments, scFv (single-chain Fv) fragments, linear antibodies, monospecific or multispecific antibody fragments, e.g., bispecific, trispecific, tetraspecific, and multispecific antibodies (e.g., diabodies, triabodies, tetrabodies), monovalent or multivalent antibody fragments, e.g., bivalent, trivalent, tetravalent, and multivalent antibodies, minibodies, chelating recombinant antibodies, tribodies or bibodies, intrabodies, nanobodies, small modular immunopharmaceuticals (SMIPs), binding domain immunoglobulin fusion proteins, camelized antibodies, and VHH-containing antibodies. Additional examples of antigen-binding antibody fragments are known in the art.

[0149] The term "complementarity determining region" or "CDR" refers to short polypeptide sequences within the variable regions of both heavy and light chain polypeptides that are primarily responsible for mediating specific antigen recognition. The term "framework region" refers to amino acid sequences within the variable regions of both heavy and light chain polypeptides that are not CDR sequences and are primarily responsible for maintaining the proper positioning of the CDR sequences to enable antigen binding. Although the framework region itself is typically not directly involved in antigen binding, as is known in the art, certain residues within the framework region of a particular antibody may be directly involved in antigen binding or may affect the ability of one or more amino acids within the CDR to interact with the antigen.

[0150] Examples of antibodies are anti-PCSK-9 mAb (e.g., alirocumab), anti-IL-6 mAb (e.g., sarilumab), and anti-IL-4 mAb (e.g., dupilumab).

[0151] Pharmaceutically acceptable salts of any of the APIs described herein are contemplated for use as drugs or medicaments in drug delivery devices. Pharmaceutically acceptable salts include, for example, acid addition salts and base salts.

[0152] Those skilled in the art will understand that modifications (addition and / or removal) to the various components of the APIs, formulas, devices, methods, systems, and embodiments described herein may be made without departing from the full scope and spirit of the present disclosure, which encompasses such modifications and all equivalents thereof. [Explanation of symbols]

[0153] 10 Housing (casing) 11a, 11b windows 12 Inserts 13 Side wall 14 tubes 15 Arm 16 Bottom wall 17 threads 18 spline teeth 19 Annular second member 19a spline teeth 19b Arm (spline) 19c Arm (click clip) 19d opening 20 Reservoir unit body 30 Piston rod 40 driving member 40a First driving member 40b Second driving member 41 spline teeth 42 First Locking Function 42a First locking part 42b Second locking part 43 Secondary Locking Function 44 Rock 45 Thread guide 50 nuts 60 Dose setting member 60a Lower portion of dose setting member 60b upper portion of dose setting member 70 buttons 80 Dose Selector 90 Torsion spring 91 Hook 100 reservoir 110 Gauge Elements 120 Clutch plate 130 Clutch spring 140 Bearing part I axis D Delivery direction

Claims

1. A mechanism unit for a drug delivery device comprising: a housing (10) having a proximal end and a distal end; a piston rod (30) movable relative to the housing (10); a dose setting and driving mechanism configured to perform a dose setting operation to set a dose to be delivered, and a dose delivery operation to deliver the set dose by transmitting a delivery force to the piston rod (30) to drive the piston rod (30) distally relative to the housing (10) in a dose delivery operation, the dose setting and driving mechanism comprising: a first drive member (40a) that is axially fixed and rotatable relative to the housing (10) and that mechanically cooperates with the piston rod (30) to transmit a delivery force to the piston rod (30), wherein rotation of the first drive member (40a) relative to the housing (10) in a delivery direction causes the piston rod (30) to move distally, and rotation of the first drive member (40a) in a direction opposite to the delivery direction causes the piston rod (30) to move proximally; a second drive member (40b) mechanically coupled to said first drive member (40a) and arranged to transmit a delivery force to said first drive member (40a); a clutch mechanism having at least two different states, a set state and a delivery state, wherein in the set state, the second drive member (40b) is fixed to be non-rotatable relative to the housing (10) at least against rotation in the delivery direction, and in the delivery state, the second drive member (40b) is rotatable relative to the housing (10) in the delivery direction, and in the set state, the first drive member (40a) is rotatable relative to the second drive member (40b) and the housing (10) at least in the delivery direction, and in the delivery state, the second drive member (40b) is locked to be non-rotatable relative to the first drive member (40a), at least against rotation of the second drive member (40b) relative to the first drive member in the delivery direction; The second drive member (40b) is axially movable relative to the first drive member (40a) and the housing (10) to switch between a set state and a delivery state; A mechanism unit for said drug delivery device.

2. A mechanism unit for a drug delivery device as described in claim 1, wherein the dose setting and driving mechanism includes a dose setting member (60) that is movable relative to the housing (10) from an initial position to a dose setting position in a setting state to set a dose of drug.

3. the mechanism unit is configured to be coupled to the reservoir unit to assemble two units for the drug delivery device; A mechanism unit for a drug delivery device as described in claim 1 or 2, wherein the first drive member (40a) is accessible from outside the housing (10) for operation in a set state so that the position of the piston rod (30) relative to the housing (10) can be adjusted by rotating the first drive member (40a) before or after the mechanism unit and the reservoir unit are connected.

4. The first drive member (40a) is engaged with the piston rod (30); A mechanism unit for a drug delivery device according to any one of claims 1 to 3, wherein the piston rod (30) is engaged with the housing (10).

5. The first drive member (40a) is threadedly engaged with the piston rod (30); 5. A mechanism unit for a drug delivery device according to claim 4, wherein the piston rod (30) is splined to the housing (10).

6. 6. A mechanism unit for a drug delivery device according to claim 5, wherein the first drive member (40a) is rotatable relative to the piston rod.

7. The first drive member (40a) is splined to the piston rod (30); 5. The mechanism unit for a drug delivery device according to claim 4, wherein the piston rod (30) is threadedly engaged with the housing (10).

8. 8. The mechanism unit for a drug delivery device according to claim 7, wherein the first drive member (40a) is fixed non-rotatably to the piston rod (30).

9. A mechanism unit for a drug delivery device according to any one of claims 1 to 8, wherein the first drive member (40a) is fixed against proximal and distal movement relative to the housing (10).

10. The first drive member (40a) includes a first locking feature (42); The second drive member (40b) includes a second locking feature (43); A mechanism unit for a drug delivery device according to any one of claims 1 to 9, wherein in the delivery state the first locking feature (42) engages with the second locking feature (43).

11. 11. A mechanism unit for a drug delivery device according to claim 10, wherein in the set state the first locking feature (42) and the second locking feature (43) are disengaged.

12. 11. A mechanism unit for a drug delivery device according to claim 10, wherein in the set state the first locking feature (42) engages with the second locking feature (43).

13. 13. A mechanism unit for a drug delivery device as described in claim 10 or 12, wherein the first locking feature (42) and the second locking feature (43) are configured such that when the first locking feature (42) engages with the second locking feature (43), the first locking feature (42) is rotatable relative to the second locking feature (43) in the delivery direction and is fixed non-rotatably relative to the second locking feature (43) in the opposite direction to the delivery direction.

14. The mechanism unit according to any one of claims 1 to 13, The mechanism unit includes an energy storage unit (90), wherein the energy storage unit is configured such that, in a setting state, energy is stored in the energy storage unit by movement of a setting member by a user, and the energy storage unit is configured such that, in a delivery state, the stored energy in the energy storage unit is released to support the delivery process.

15. 15. A mechanism unit for a drug delivery device according to claim 14, wherein the energy storage unit (90) is a drive spring.

16. 1. A drug delivery device comprising: A mechanism unit according to any one of claims 1 to 15; The drug delivery device includes a reservoir (100) for holding a drug, or a reservoir unit provided for holding a reservoir (100).

17. The drug delivery device of claim 16, wherein the reservoir (100) is a cartridge.

18. 18. The drug delivery device of claim 16 or 17, wherein the drug delivery device is an injection device.

19. 1. A method of manufacturing a drug delivery device, comprising: a) providing a reservoir unit including a reservoir (100) containing a drug, wherein a stopper is movably held within the reservoir, the reservoir being held within a reservoir unit body (20); b) providing a mechanism unit according to any one of claims 1 to 15; c) determining the position of the plug relative to the reservoir unit body (20); d) determining a desired piston rod position of the piston rod (30) relative to the housing (10) based on the determined bung position, the desired piston rod position being determined such that the piston rod (30) and the bung are located at a predetermined distance from each other when the mechanism unit and the reservoir unit are coupled, and determining a specific displacement distance that the piston rod (30) must be displaced distally relative to the housing (10) to reach the desired piston rod position; e) in a set state of the mechanism unit, rotating the first driving member (40a) relative to the second driving member (40b) to displace the piston rod (30) by a specific displacement distance relative to the housing (10); f) after step e), connecting the reservoir unit and the mechanism unit to each other for the drug delivery device.

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