Drive mechanism for an injection device - Patent application

Abstract

The present invention relates to a drive mechanism for an injection device for setting and dispensing a dose of a medicament, the drive mechanism comprising an inner body (20) fixable within a housing (10) of an injection device (1), the inner body comprising an elongated shaft (20a) extending in an axial direction (z) and having an external thread (21), a tubular indicating member (60; 160) having an internal thread (61) engaging with the external thread (21) of the inner body (20), and a dose member (70) axially displaceable relative to the indicating member (60; 160) between a dose setting position (S) and a dose dispensing position (D), the indicating member (60; 160; 260) being movable in the axial direction (z) between a blocking position (B) and a release position (R) and comprising at least one blocking member (66) engageable with a blocking thread (27; 227) on the outer periphery of the inner body (20), the blocking thread (27; 227 and the external thread ( 21;221 have the same pitch, and at least one blocking member (66) of the indicator member (60;160) is rotatable relative to the inner body (20;220) over a predetermined number of rotations between a distal zero dose position (Z) on the inner body (20;220) and a proximal maximum dose position (M) on the inner body (20;220), and when in a blocking position (B), the blocking member (66) is in contact with the dose member (70) and the blocking screw (27;2 27) to prevent axial displacement of the dose member (70) from the dose setting position (S) toward the dose dispensing position (D), and the axial position (27a) of the distal end (27a) of the blocking screw (27, 227) on the inner body (20; 220) is offset proximally (5) from the distal zero dose position (Z) by 10% to 60% of the axial distance between the distal zero dose position (Z) and the proximal maximum dose position (M).

Description

[Technical field]

[0001] In one aspect, the present invention relates to a drive mechanism for an injection device, such as a pen injector, for setting and dispensing a dose of a medicament. In particular, the present invention relates to an injection device providing a minimum dose mechanism, i.e. a dose setting and dispensing mechanism operable to dispense a dose only if the dose exceeds a predetermined minimum threshold. [Background technology]

[0002] Injection devices for setting and dispensing single or multiple doses of liquid medicaments are per se well known in the art. In general, such devices have a purpose substantially similar to that of a conventional syringe.

[0003] Injection devices, and in particular pen injectors, must meet several user-specific requirements. For example, in the case of patients suffering from chronic diseases such as diabetes, the patient may be physically debilitated and may also have poor eyesight. Therefore, a suitable injection device, especially for home drug therapy, must be robust in construction and should be easy to use. Furthermore, the operation and general handling of the device and its components should be clear and easily understandable. Furthermore, the dose setting and dose dispensing procedures must be easy to operate and unambiguous.

[0004] Typically, such devices comprise a housing including a cartridge holder adapted to receive a cartridge at least partially filled with the medicament to be dispensed. Such devices further comprise a drive mechanism, usually having a displaceable piston rod adapted to operatively engage a piston of the cartridge. By means of the drive mechanism and its piston rod, the piston of the cartridge can be displaced in a distal or dispensing direction and thus expel a predetermined amount of medicament through a piercing assembly that is removably coupled to a distal end section of the housing of the injection device.

[0005] The medication dispensed by the injection device is provided and contained in a multi-dose cartridge. Such cartridges typically comprise a glass barrel sealed distally by a pierceable seal and further sealed proximally by a piston. In reusable injection devices, the empty cartridge can be replaced with a new cartridge. In contrast, disposable injection devices are intended to be discarded when the medication in the cartridge has been dispensed or used up.

[0006] WO 2014 / 033197 A1 and WO 2014 / 033195 A1 disclose disposable and reusable drug delivery devices for selecting and dispensing multiple user-variable doses of a medicament, the devices comprising a housing, a cartridge holder for holding a cartridge containing the medicament, a piston rod displaceable relative to the cartridge holder, a drive part coupled to the piston rod, a display member indicating a set dose and coupled to the housing and to the drive part, and a button coupled to the display member and to the drive part.

[0007] WO 2012 / 049140 A1 describes a dose setting mechanism having a clutch nut threadably engaged to a distal end of a clutch and further engaged to a dose dial sleeve via an internal ratchet. WO 2012 / 049139 A1 describes a clutch blocker with an external thread that threadably engages a clutch plate. Axial movement of the clutch plate tends to rotate the clutch blocker unless rotation is prevented by a keying feature running through a first path of the dual state path. US 2013 / 0289518 A1 describes another principle for implementing a minimum dose size. In this document, a combination of helical and axial clutch paths with helical and axial portions on the inner surface of the outer body is described. WO 2012 / 049138 A1 describes a minimum dose setting mechanism based on a split thread insert between a dose dial sleeve and a housing.

[0008] In some applications, it may be advantageous to limit the minimum drug dose that can be delivered from the device, as well as the maximum dose.This may ensure, for example, that only therapeutically effective doses can be administered.Such functionality may be particularly relevant for drug combinations, when a minimum amount of combined drugs is required to ensure sufficient delivery of one component of the combination to be therapeutically effective, while allowing some variation in dose that may be important for other components of the combination.

[0009] In some applications it may be advantageous to provide a device that allows for the delivery of only one fixed dose value, but also allows for a "priming" operation to be performed before each dose is administered.

[0010] A further application may be for treatments where a range of discrete, non-continuous, pre-fixed doses may be required, for example a range of doses may be required to meet the therapeutic needs of different user groups or to allow individual users to deliver different doses at different times, e.g. in the morning or in the evening.

[0011] EP 3256194 B1, A drive mechanism for an injection device providing a minimum dose function. It is a further object that the drive mechanism also provide a maximum dose function. The drive mechanism may allow priming of the device, allowing a user to dial and deliver a small dose of medication, typically 2 International Units (IU), to check whether the flow rate is occurring correctly through a needle assembly that is removably attachable to the distal dispensing end of the device.

[0012] However, the limitation of a fixed minimum dose reduces the flexibility that may be required for certain categories of patients, for example a titration range may be desirable for patients at the beginning of treatment where the most suitable dosage for the patient has not yet been determined. Furthermore, a fixed minimum dose may result in wasting a significant amount of product that remains in the cartridge unusable. Summary of the Invention [Problem to be solved by the invention]

[0013] It is therefore an object of the present invention to provide a drive mechanism for an injection device that provides fixed dose functionality while maintaining the flexibility of selecting a variable dose.

[0014] The implementation of the desired minimum and / or maximum and / or variable dose functionality should be feasible by modifying only a limited number of existing device components. It is a further object to individually change the minimum and maximum and / or variable dose values ​​or dose sizes by changing only a single or a few components of the device. Thus, the minimum and / or maximum and / or variable dose functionality of the device or its drive mechanism should be configurable by replacing only one or a few components of the device or its drive mechanism. It is a further object that the improved drive mechanism is universally applicable to a wide variety of drive mechanisms and injection devices. In particular, the improved drive mechanism should be equally applicable to disposable and reusable injection devices. [Means for solving the problem]

[0015] This object is solved by a drive mechanism for an injection device having the features of claim 1.

[0016] In a first aspect, the invention relates to a drive mechanism for an injection device. The injection device is operable to set and dispense, typically by injection, multiple doses of a variably sized medicament. The drive mechanism of the injection device comprises mechanically inter-engaged components necessary to apply a distally directed thrust to a piston of a cartridge filled with a liquid medicament. The drive mechanism comprises an inner body fixable in a housing of the injection device. The inner body comprises at least an elongated shaft extending in an axial direction (z) and having an external thread. The external thread is a helical thread and has a constant or variable pitch in the axial direction. The inner body is fixable in the housing in a non-movable manner. Thus, the inner body is fixable axially and rotationally in a tubular or cylindrical housing of the injection device. The inner body and the housing may also be integrally formed. Thus, the inner body may be part of the housing.

[0017] The drive mechanism further comprises a tubular indicating member having an internal thread that engages or mates with the external thread of the inner body. The tubular indicating member is axially displaceable relative to the inner body, and in particular relative to its elongate shaft, as it rotates helically. Typically, the pitch and friction of the threaded engagement between the indicating member and the inner body is such that the indicating member begins to rotate when subjected to an axial force against the inner body.

[0018] In addition, the drive mechanism comprises a dose member axially displaceable relative to the indicator member between a dose setting position (S) and a dose dispensing position (D). The dose member may be rotatable relative to the inner body. The dose member may also be axially displaceable relative to the inner body. Typically, the dose member is rotatable along a helical path relative to the inner body to set the dose. Furthermore, the dose member may be axially displaceable in a non-rotational manner relative to the inner body to dispense the dose. The dose member and the indicator member may be selectively rotationally engaged, typically by a clutch, which either locks or releases the rotational engagement between the dose member and the indicator member.

[0019] In the dose setting mode, the clutch is typically closed, so that the torque applied to the dose member is transmitted to the indicator member, which then displaces axially relative to the inner body together with the dose member upon threaded engagement with the inner body. For dose dispensing, the clutch between the indicator member and the dose member may be released, so that the dose member undergoes a purely translational displacement while the indicator member may rotate as it returns to its initial position. Thus, during dose dispensing, the dose member may be rotationally locked relative to the inner body, while the indicator member is free to rotate relative to the indicator body and thus relative to the dose member.

[0020] Depending on the specific embodiment of the drive mechanism, either a rotating indicator member or a translationally displaceable dose member is operably engaged to the piston rod to drive the piston rod in the distal dose dispensing direction during dose dispensing to displace the cartridge piston in the distal dose dispensing direction.

[0021] The indicating member further comprises at least one blocking member that is axially movable and / or flexible between a blocking position (B) and a release position (R). The blocking member is engageable with a blocking structure located on an outer periphery of the inner body. Typically, the blocking structure is located on an outer periphery of the elongate shaft of the inner body. The radial extent of the blocking structure typically corresponds to or is substantially equal to the radial extent of the external thread of the elongate shaft. In other embodiments, the radial extent of the blocking structure may exceed the radial extent of the external thread.

[0022] At least one blocking member of the indicator member is rotatable with respect to the inner body by a predetermined number of rotations, i.e. capable of performing a relative dose setting movement. Due to the threaded engagement of the indicator member with the inner body, this relative rotation results in a relative axial displacement of the indicator member with the inner body between a zero dose position (Z) of the at least one blocking member on the inner body and a maximum dose position (M) of the at least one blocking member on the inner body. Typically, the zero dose position (Z) of the at least one blocking member on the inner body is the most distal position of the at least one blocking member when the dose member is in its dose setting position (S), and the maximum dose position (M) of the at least one blocking member on the inner body is the most proximal position of the at least one blocking member when the dose member is in its dose setting position (S).

[0023] When in the blocking position (B), the blocking member axially engages the dose member and the blocking structure. In this blocking position, the dose member is effectively blocked and therefore cannot be axially displaced from the dose setting position towards the dose dispensing position relative to the inner body or relative to the dose member. Thus, when the blocking member of the indicator member engages the blocking structure of the inner body, as may typically occur during dial setting or helical rotational movement during dose setting, the blocking member serves to block axial displacement of each of the dose members by effectively preventing axial displacement of the dose member relative to the indicator member and / or relative to the body or housing. In this blocking state, the clutch between the dose member and the indicator member is effectively locked in a closed configuration, so that the drive mechanism remains in a dose setting mode characterized by the dose member being located in the dose setting position (S) relative to the indicator member.

[0024] Depending on the interengagement of the blocking member and the blocking structure, particularly the geometry and extent of the blocking structure, dose dispensing may be effectively blocked for a predefined range of dose sizes. Thus, minimum and maximum thresholds may be defined between which dose dispensing is effectively blocked and prevented. According to the present disclosure, the axial position of the distal end of the blocking screw on the inner body is offset proximally from the distal zero dose position (Z) by 10% to 60% of the axial distance between the distal zero dose position (Z) and the proximal maximum dose position (M). In one embodiment, the axial position a) of the distal end of the blocking screw on the inner body is offset proximally from the distal zero dose position (Z) by 20% to 30%, such as up to 25%, of the axial distance between the distal zero dose position (Z) and the proximal maximum dose position (M). If the dose setting range between the zero dose position (Z) of the at least one blocking member on the inner body and the maximum dose position (M) of the at least one blocking member on the inner body is typically 60 IU to 100 IU, e.g. 80 IU, the minimum threshold defines the maximum dose value of the titration range, i.e. the variably settable dose, which is far above the dose used for the priming procedure, i.e. 2 IU or 3 IU.

[0025] In other words, the axial position of the blocking screw on the distal end of the blocking structure or on the inner body defines the maximum size of the variable dose, which can be selected and dispensed individually, for example for titration reasons or for a priming procedure. In addition, this titration range or variable dose range can be used when the amount of drug in the cartridge is lower than the amount of the dose intended to be dispensed. In this case, the amount of the dose intended to be dispensed can be divided between the remaining amount in the cartridge, which is set and dispensed in a first step, after which a new (full) cartridge is inserted into the device or a new device with a full cartridge is prepared in order to set and dispense the remaining amount of the dose intended to be dispensed in a second step.

[0026] The blocking member remains in the release position as long as it is axially separated from the blocking structure and as long as it is located distally from the distal end of the blocking structure. This is typically the case when the indicator member, and thus the entire drive mechanism, is in the zero set dose configuration, i.e. when the blocking member is in its distal zero dose position (Z), or when a dose within the titration range or variable dose range has been set. When a dose above this lower threshold has been set, the blocking member engages the blocking structure. The blocking member is then prevented from bending distally, or in fact is slightly bent proximally to prevent distally directed displacement for dispensing the dose member.

[0027] In the drive mechanism for the injection device described above, the setting of the variable titration dose is allowed within a first lower dose range with standard titration, allowing dosing flexibility at the start of treatment and allowing dose splitting and minimizing drug waste since all doses are injectable within this dose range. Furthermore, a second range, e.g., a maintenance range, ensures simplified dose dialing and safe dosing at preset fixed doses above the variable titration dose. The function of the preset fixed dose within the second dose range is realized by providing a blocking member on the display member and a blocking structure on the inner body. The position of the section of the blocking structure on the inner body defines which doses are deliverable and which doses are blocked. According to the present disclosure, the distal end of the blocking structure is arranged such that the setting of the variable titration dose, e.g., up to 20 units, is allowed, whereas higher doses above 20 units can only be dispensed in preset fixed dose steps of, e.g., 10 units each. In other words, the patient can select and dispense a variable dose between 0 and 20 Units, or higher doses in increments of 10 Units, ie, 30 Units, 40 Units, 50 Units, 60 Units, 70 Units, or 80 Units.

[0028] In embodiments of the drive mechanism, at least one blocking member of the indicator member may be rotatable relative to the inner body between a distal zero dose position (Z) on the inner body and a proximal maximum dose position (M) on the inner body by 1080° (3 full rotations) to 2160° (6 full rotations), for example 1440° (4 full rotations) or 1800° (5 full rotations).

[0029] The blocking member may be axially curved in response to engagement with the blocking structure. Furthermore, the axially curved blocking member may be supported and mechanically reinforced by the blocking structure to provide a fairly strong and robust axial abutment against the dose member. Alternatively, the blocking member may be axially engaged with the blocking structure without being axially curved. In such an uncurved state, the blocking member is merely prevented from moving axially relative to the blocking structure. Thus, even in such an uncurved but engaged configuration, the blocking member engaged with the blocking structure is axially restrained or axially fixed in at least one axial direction, typically in the distal direction, relative to the housing. When engaged with the blocking structure, the blocking member may be axially engaged with the dose member and is then also axially restrained or axially fixed relative to the housing.

[0030] Generally, the blocking member engages the proximal side of the blocking structure so that when a user attempts to dispense a dose, the blocking member cannot be bent distally by the dose member while engaged with the blocking structure.

[0031] According to one embodiment, the blocking structure comprises a blocking screw on the elongated shaft of the inner body. The blocking screw may extend between interlocking portions of the outer thread of the inner body, but may also be axially separated from the outer thread on the shaft. The blocking screw and the outer thread have the same pitch. Typically, the blocking screw, and thus the interlocking portion of the blocking screw, may be axially centered between adjacent interlocking portions of the outer thread of the inner body, and in particular of its elongated shaft. Because the blocking screw and the outer thread have the same pitch, and because the blocking screw and the outer thread are axially offset, the blocking member remains in its blocking position during engagement with the blocking screw when the indicator member undergoes helical rotation relative to the inner body during dose dialing.

[0032] Typically, the axial extension of the blocking screw is less than the entire axial extension of the outer thread. As seen axially, the blocking screw may be located inside the outer thread, whereby both the proximal and distal ends of the blocking screw are located in an axial region bounded by the proximal and distal ends of the outer thread. In alternative embodiments, depending on the axial position of the inner thread of the indicator member relative to the axial position of the blocking member, it is also conceivable that the proximal and / or distal ends of the blocking screw are located beyond the proximal or distal ends of the outer thread.

[0033] When the indicator member rotates relative to the inner body, the blocking member may bend axially as it engages one end of the blocking screw. The blocking member may then remain curved as it slides along the blocking screw, and the blocking member returns to its release position as it passes the opposite axial end of the blocking screw. If the blocking member passes the proximal end of the blocking screw during the dose-increasing rotation of the indicator member relative to the inner body, the blocking member may be axially bent by the dose member under the effect of the dose member advancing axially distally to dispense the dose. In this state, the dose member is free to displace axially relative to the indicator member a sufficient distance to release the clutch between the indicator member and the dose member. When the clutch is released, the device is switched to a dose-dispensing mode and the dose-dispensing procedure may be initiated.

[0034] According to a further embodiment, the blocking member comprises a flexible arm which extends tangentially around the circumference of the indicating member. The flexible arm of the blocking member may be arcuate and may follow the contour of the side wall of the indicating member. To provide an axial bending or axial deformation of the blocking member relative to the indicating member, the blocking member is arranged at the axial end of the indicating member or is located in a recess in the side wall, in which it is free to elastically bend or pivot axially. The flexible arm does not have to extend strictly tangentially and perpendicularly to the axial direction of the tubular indicating member. It is generally conceivable that the flexible arm extends at a certain angle with respect to the tangential or circumferential direction and the axial direction of the indicating member.

[0035] Typically, the flexible arm is integrally formed with the display member. The flexible arm may comprise a base portion integrally formed with the blocking member, from which the flexible arm extends towards a free end. Due to the flexibility of the material and the geometry of the flexible arm, it is in particular its free end that is axially flexible, pivotable or displaceable to switch between its blocking position and its release position. Implementing the blocking member as a flexible arm that substantially matches the outer circumference of the display member is a rather space-saving and cost-effective solution. Furthermore, the integral implementation of the blocking member in the display member requires only the modification of one component of the drive mechanism and does not require the assembly of additional components.

[0036] The same is valid for the blocking structure. The blocking structure can be implemented in the inner body without the need to provide a separate component. The general function and behavior of the minimum dose function can be changed by using an appropriately configured blocking structure. Changing the minimum dose function only requires replacing the inner body component having the first blocking structure with a different inner body having an alternative blocking structure.

[0037] In another embodiment, the blocking member comprises a radially inwardly extending protrusion at the free end section of the flexible arm for engaging with the blocking structure. In this way, modifying the indicator member to implement the blocking member does not affect components of the injection device or the drive mechanism located at or along the outer circumference of the indicator member. Furthermore, the radially inwardly extending protrusion allows the free end of the blocking member's flexible arm to be axially displaceable when engaging with the blocking thread of the blocking structure. Furthermore, the inwardly extending protrusion allows the free end of the blocking member to be axially supported and axially restrained when axially abutting or axially engaging against the blocking structure. Any distally directed force transmitted from the dose member to the indicator member when axially abutting or axially engaging against the blocking structure is then counteracted by the axial abutment of the inwardly extending protrusion of the blocking member. Depending on the geometry or slope of the blocking structure compared to the slope and geometry of the external thread of the inner body, the degree of axial displacement or axial bending of the free end of the blocking member can be varied and controlled.

[0038] According to another embodiment, the blocking member comprises an axially facing abutment at its free end section, which abuts axially against a corresponding abutment of the dose member. Typically, the abutment of the blocking member may face in a proximal direction so as to axially abut against a correspondingly shaped distally facing abutment of the dose member. The distal abutment of the dose member may coincide with the distal end of the dose member. It is also conceivable that the dose member and the indicator member are arranged in a somewhat intertwined or nested fashion.

[0039] In a typical embodiment, the dose setting position of the dose member coincides with the position of its proximal end relative to the indicator member. By pushing the dose member in a distal direction, the dose member advances to a dose dispensing position. In such an embodiment, the abutment of the blocking member typically faces in a proximal direction. When the blocking member is in the release position, there may be a small axial gap between the abutment of the blocking member and the corresponding abutment of the dose member. In the release position, the dose member is free to displace distally to reach the dose dispensing position relative to the indicator member. Alternatively, when in the release configuration, the blocking member may abut axially against the dose member. The blocking member and the blocking structure may then be disengaged. In summary, in the release configuration, the dose member is distally displaceable relative to the housing.

[0040] The blocking member does not necessarily have to be displaced or bent axially when engaging with the blocking structure of the elongate shaft of the inner body. It is also conceivable that the blocking member remains unbent but is prevented from bending in the distal direction when the blocking member and the blocking structure are engaged with each other. In such an embodiment, the blocking member may even be permanently axially engaged with the abutment of the dose member. When in the released position, the blocking member is then still axially abutting against the dose member, but due to release from the blocking structure, the blocking member is then free to bend or pivot in the distal direction, such that the dose member is axially displaceable to initiate dose dispensing.

[0041] When in the blocking configuration, the dose member axially engages and abuts the blocking member and further abuts the blocking structure such that any distally directed forces applied to the dose member are counteracted and transmitted to the blocking structure and thus to the housing.

[0042] In a further embodiment, the axial position of the proximal end of the blocking structure on the elongate shaft of the inner body defines a minimum size of the therapeutic dose. The aforementioned blocking of the dose member is maintained until the indicator member is further dialed to disengage and release the blocking member. When the indicator member is dialed above such a maximum threshold value corresponding to the minimum size of the therapeutic dose, the blocking member is disengaged from the blocking structure such that distal displacement of the dose member is no longer prevented. Once a desired size therapeutic dose is set that exceeds the pre-determined minimum size, the drive mechanism is operable to initiate the dispensing procedure.

[0043] According to a further embodiment, the distal end of the blocking structure or blocking screw is chamfered. In this way, the blocking member, and in particular its radially inwardly extending projection which directly mechanically engages the blocking screw, undergoes a small axial displacement in accordance with the angle of the chamfered distal end of the blocking screw as the blocking member and the blocking screw interengage during dose setting.

[0044] The chamfered distal end can provide for smooth and reliable engagement of the blocking member with the blocking screw as the radially inwardly extending projection of the blocking member passes the end of the blocking screw. The proximal end of the blocking screw can be similarly chamfered to the distal end to provide for smooth and reliable engagement with the blocking member when dialing down to cancel a dose selection or when dialing in a dose reduction direction.

[0045] In a further embodiment, when the indicator member is rotated in the dose increase direction, the protrusion of the blocking member slides over the chamfer of the distal end of the blocking screw, causing the free end section of the blocking member to bend from its release position towards its blocking position. Instead, the protrusion slides over the chamfer and axially abuts the proximally facing edge of the blocking screw. As the protrusion of the blocking member passes the chamfered end of the blocking screw, the protrusion slides along the proximally facing edge of the blocking screw and therefore remains axially abutting the blocking screw, thereby preventing distal displacement of the blocking member relative to the blocking screw. In one embodiment, the blocking member remains curved and axially abuts the blocking screw in the proximal direction because the blocking screw and the external threads of the elongated shaft of the inner body have the same lead.

[0046] In this way, as long as the blocking member is engaged with the blocking screw, the blocking member is axially supported by the proximal edge of the blocking screw. Any axially and distally directed forces acting on the blocking member, e.g. caused by the dose member, are directly supported and transmitted to the blocking screw and thus to the inner body. In this way, a fairly direct axial force transmission between the dose member and the inner body can be provided, providing a fairly intuitive and direct mechanical feedback to the user that distal displacement of the dose member has indeed been prevented.

[0047] The location of the axial support provided to the blocking member by the proximally facing edge of the blocking screw in the blocking state is also beneficial in that the flexible portion of the blocking member does not have to withstand or counteract large axial forces, so that the blocking member can be designed with a thin or fine structure, thereby achieving the desired degree of flexibility for low dispensing forces.

[0048] When the blocking member is located proximally from the proximal end of the blocking screw, then the blocking member is no longer axially engaged with the blocking structure and the dose may be dispensed. To dispense the dose, the dose member is axially displaced distally, causing the blocking member to bend distally to allow disengagement of the clutch between the dose member and the indicating member. Once disengaged, a protrusion on the blocking member may slide distally over a distally facing edge of the blocking screw as the blocking member distally passes the proximal end of the blocking screw when the indicating member rotates in the dose reduction direction during dose delivery.

[0049] During delivery of the dose, the geometry and design of the blocking member and blocking structure are such that the radially inwardly extending projection of the free end section of the blocking member slides along the distally facing edge of the blocking screw. The projection does not necessarily have to slide along the distal edge. The projection may be advantageously distally separated from the distally facing edge of the blocking structure. However, the projection is axially separated from the proximal edge of the blocking screw. At the start of the dose dispensing procedure, the blocking member undergoes a distally directed displacement or distally directed pivoting under the action of the dose member advancing distally. The radially inwardly extending projection of the blocking member then slides along the distally facing edge of the blocking screw but does not engage its proximal facing edge.

[0050] During dose dispensing, the blocking member, and in particular its radially inwardly extending projection, will pass distally through the proximal end of the blocking structure of the inner body. If the dose member is then released and the dispensing procedure is suddenly interrupted, the projection of the blocking member may abut axially against the distally facing edge of the blocking screw. When the dose member is released, the blocking member cannot bend back proximally because it is constrained by the blocking screw. Thus, when the dose member is pushed distally again, dispensing can continue.

[0051] In another embodiment, the display member comprises a number sleeve and a dial sleeve. At least one blocking member is located on the dial sleeve or at least one blocking member is integrally formed with the dial sleeve. Typically, the number sleeve and the dial sleeve are permanently rotationally and axially locked to one another. Typically, it is the number sleeve of the display member that is threadedly engaged with the external threads of the inner body.

[0052] Splitting the indicator into two separate components, the number sleeve and the dial sleeve, is beneficial for the injection moulding of the individual components and for their assembly in the drive mechanism. The number sleeve is the part of the indicator which is provided on its outer circumference with consecutive numbers or symbols indicating the size of the actual set dose. Depending on the helical movement or position relative to the external thread of the inner body, the respective numbers on the number sleeve appear in the aperture of a window in the outer body of the housing of the injection device.

[0053] The dial sleeve may be a different color than the number sleeve. Furthermore, the dial sleeve may be manufactured or constructed from a different injection moldable plastic material compared to the number sleeve. Thus, at least one blocking member or all blocking members of the blocking mechanism may be located on or integrally formed with the dial sleeve. Because the dial sleeve does not need to be printed or coated with numbers or indicia indicating the dose, more material choices are available.

[0054] For example, the dial sleeve and thus the at least one blocking member attached to or integrally formed therewith may be made of a plastic material such as polyoxymethylene (POM). Such plastic materials are difficult to print on, but offer desirable mechanical properties in terms of durability, flexibility and stability, especially with respect to the at least one blocking member. Thus, by separating the display member into two separate sleeves, the number sleeve and the dial sleeve, and by providing at least one or all blocking members on the dial sleeve, an optimized plastic material for the manufacture of the dial sleeve and its blocking members can be selected. This plastic material does not have to meet any printing requirements or constraints and can be mechanically optimized for the mechanical demands and requirements of the at least one blocking member.

[0055] According to another embodiment, the inner body may be provided with a first maximum dose stop and an optional second maximum dose stop at its outer periphery, which engage with the first maximum dose stop and the second maximum dose stop, respectively, extending radially inwards of the indicator member. The first maximum dose stop and also the optional second maximum dose stop of the inner body and the indicator member engage with each other and simultaneously when the indicator member reaches a maximum dose position. The maximum dose position limits the amount of drug injected by a single dose dispensing action. Typically, the maximum dose size may be limited to, for example, 60 IU, 80 IU, 120 IU. The mutually corresponding maximum dose stops of the inner body and the indicator member typically extend in the axial and radial directions. Thus, as soon as the maximum dose position is reached, the tangentially facing stop surfaces engage and abut each other.

[0056] By providing two pairs of axially separated maximum dose stops, an improved and well-defined stop function is provided. In this way, the stop force preventing rotation of the dose member beyond the maximum dose configuration can be divided into two pairs of axially separated dose stops. As a result, the overall design of the dose stops, in particular their dimensions, can be reduced. Also, the mechanical load between the mutually engaging dose stops of the indicator member and the inner body is reduced compared to the embodiment using only one pair of dose stops.

[0057] According to a further embodiment, the maximum dose stop of the indicator member facing in the tangential direction is located at the free end section of the blocking member. The abutment at the free end section of the blocking member may face in the proximal direction so that the flexible arm of the blocking member includes an L-shaped structure in some way. It is generally considered that the maximum dose stop of the indicator member, in particular the maximum dose stop located proximally of the indicator member, is located at the free end section of the blocking member. Typically, this maximum dose stop faces towards the base part of the flexible arm of the blocking member, where the flexible arm joins the indicator member. In this way, the flexible arm is subjected to a tangentially directed tensile force when its maximum stop engages with a correspondingly shaped maximum stop of the inner body. This tensile force runs substantially parallel to the L-shaped extension of the flexible arm. Any stop force or torque transmitted between the flexible arm and the maximum dose stop of the indicator member does not impair the mechanical integrity of the flexible arm. Due to the orientation and location of the stop surfaces of the flexible arms, the arms can be designed as relatively thin and flexible structures, while still being capable of transmitting significant forces and / or torques under tension.

[0058] In a further embodiment, the blocking screw comprises at least one recess, interruption or gap having a size to accommodate the blocking member and / or its radially inwardly extending projection. In this way, the drive mechanism can be configured as a fixed dose drive mechanism, and in this way only one or several doses of a predetermined size can be dispensed. The circumferential or tangential size of the gap(s) defines the dose size that can be dispensed by the device. The tangential size of at least one gap is at least as large as the blocking member or its radially inwardly extending projection that actually passes through the gap in the blocking member when initiating the dose dispensing procedure. There can be several gaps separated from each other tangentially and / or axially along the blocking screw. Dose dispensing is then only possible if the tangential position of the respective gap overlaps or axially coincides with the actual position of the blocking member or its projection. When the blocking screw has at least two recesses sized to accommodate the blocking member and / or its radially inwardly extending protrusion, two adjacent recesses may be spaced apart from each other by 10% to 20%, for example 12.5%, of the axial distance between the distal zero dose position (Z) and the proximal maximum dose position (M).

[0059] According to the present invention, and simply by the particular design and geometry of the blocking structure or blocking screw, the drive mechanism may be configured to only allow the setting and dispensing of doses of a particular or individual size.

[0060] According to a further embodiment, the drive mechanism comprises a piston rod and a tubular drive, both of which extend in the axial direction. The piston rod typically comprises a first external thread that engages with the internal thread of the inner body. Thus, rotation of the piston rod in the dispensing direction results in a distal advancement of the piston rod relative to the inner body and thus relative to the cartridge axially constrained in the housing of the injection device. Furthermore, the piston rod comprises a second external thread of opposite orientation compared to the first external thread, which is threadably engaged with the internal thread of the drive. Thus, axial non-rotational displacement of the drive in the distal direction causes a rotation of the piston rod, which advances the piston rod distally during dose dispensing due to the threaded engagement with the internal thread of the inner body. Thus, during dose dispensing, the drive undergoes a purely translational but non-rotational movement in the distal direction. For dose dispensing, the drive is typically rotationally locked to the inner body. The driver may be coupled to splines in the inner body such that the driver is prevented from rotating relative to the body during dose dispensing, but is free to displace axially relative to the body.

[0061] In the dose setting configuration, the driver may be rotationally locked or rotationally coupled to the indicator member to follow the helical motion of the indicator member relative to the inner body. In the dose setting mode, the splined engagement between the driver and the inner body is disabled or released. Instead, the driver is free to rotate following a helical path that matches the threaded engagement between the driver and the piston rod, such that the driver is axially displaceable in the proximal direction relative to the inner body and relative to the piston rod, which is stationary relative to the inner body during dose setting.

[0062] The two opposing threads of the piston rod make it possible to implement a displacement transfer ratio between the drive and the distal displacement of the piston rod, so that a rather large axial displacement requiring a rather small distribution force can be transferred to a rather short displacement of the piston rod with a rather large distribution force.

[0063] According to another embodiment, the dose member is permanently splined to the driver, whereby the driver is selectively rotationally lockable to the inner body by displacing the dose member into the dose dispensing position. When the dose member is in the dose setting position, the driver is no longer rotationally locked to the body but can freely rotate relative to the body, e.g. by a ratchet or clicker detent engagement, whereby rotation of the driver relative to the body produces an audible and tactile clicking sound, thereby indicating to the user that the subsequent discrete step of dose setting has indeed taken place.

[0064] The driver and indicator member may be axially engaged directly or indirectly to both the driver and indicator member via axial engagement of the dose member.

[0065] According to another embodiment, the dose member and the indicator member are selectively rotationally lockable and unlockable via a clutch. The clutch rotationally engages the dose member and the indicator member when the dose member is in the dose setting position. Thus, in the dose setting position, a rotation of the dose member is equally transmitted to a respective rotation of the indicator member. Typically, the dose member or at least a part thereof protrudes proximally from the proximal end of the indicator member. Rotation of the dose member in the dose increase direction displaces the dose member and the indicator member simultaneously in the proximal direction and extends proximally from the inner body or from the housing of the injection device.

[0066] The clutch between the indicator member and the dose member is released when the dose member is switched or depressed to its dispensing position. In the dispensing position or configuration, the dose member is axially displaceable distally in a non-rotating manner relative to the inner body. At the same time, the dose member, the driver and the indicator member are axially engaged. Thus, depressing the dose member or applying a distally directed dispensing force to the dose member results in a distally directed helical twisting movement of the indicator member together with a distally directed translational movement of the driver, causing a driving torque on the piston rod.

[0067] The dose member and the driver are permanently rotationally locked, for example they may be splined together such that the driver is rotationally locked to the inner body preventing the dose member from rotating during dose dispensing.

[0068] According to another aspect, the invention further relates to an injection device for setting and injecting a dose of a medicament. The injection device is typically configured as a pen-type injector. It comprises an elongated housing corresponding to and accommodating a drive mechanism as described above, and a cartridge filled with a liquid medicament, arranged inside the housing. The cartridge is typically located and accommodated in a cartridge holder forming a distal part of the housing of the injection device. If the injection device is implemented as a disposable device, the cartridge holder and the proximal housing component are typically permanently interconnected. If implemented as a reusable device, the cartridge holder is releasably connected to the proximal housing part so as to provide access to the cartridge for cartridge exchange and to allow a reset operation of the drive mechanism.

[0069] As used herein, distal direction refers to the direction of dispensing and the direction of the device, preferably a needle assembly having a dual-tipped injection needle that is inserted into the patient's biological tissue or into the skin for delivery of the medicament, is provided.

[0070] The proximal end or proximal direction refers to the end of the device or its components that is furthest from the dispensing end. Typically, at the proximal end of an injection device is an actuating member that is directly operable by the user to rotate for setting a dose, and to be pushed in the distal direction for dispensing a dose.

[0071] As used herein, the terms "drug" or "medicament" are used interchangeably to refer to a pharmaceutical formulation containing one or more active pharmaceutical ingredients or pharma- ceutically acceptable salts or solvates thereof and, optionally, a pharma- ceutically acceptable carrier. An active pharmaceutical ingredient ("API"), in the broadest sense, is a chemical structure that exerts a biological effect on humans or animals. In pharmacology, drugs or agents are used to treat, cure, prevent, or diagnose disease, or otherwise improve physical or mental health. Drugs or agents may be used for a limited duration or periodically for chronic diseases.

[0072] As described below, drugs or agents can include at least one API or combinations thereof in various types of formulations for the treatment of one or more diseases. Examples of APIs can include small molecules with molecular weights of 500 Da or less; polypeptides, peptides, and proteins (e.g., hormones, growth factors, antibodies, antibody fragments, and enzymes); carbohydrates and polysaccharides; and 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.

[0073] The drug or agent may be contained within a primary package or "drug container" adapted for use with a drug delivery device. The drug container may be, for example, a cartridge, syringe, reservoir, or other rigid or flexible container configured to provide a suitable chamber for storage (e.g., short-term or long-term storage) of one or more drugs. For example, in some cases, the chamber may 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 may be designed to store the drug for about one month to about two years. Storage may 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 may be or include a dual-chamber cartridge 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 cartridge may be configured to allow mixing of the two or more components prior to and / or during distribution into the human or animal body. For example, the two chambers may be configured to be in fluid communication with one another (e.g., by a conduit between the two chambers) to allow mixing of the two components if desired by a user prior to dispensing. Alternatively or additionally, the two chambers may be configured to allow mixing upon dispensing of the components into the human or animal body.

[0074] The drugs or agents contained in the drug delivery device as described herein may be used for the treatment and / or prevention of many different types of medical disorders. Examples of disorders include, for example, diabetes or complications related to diabetes, such as diabetic retinopathy, thromboembolism, such as deep vein thromboembolism or pulmonary thromboembolism. Further examples of disorders are acute coronary syndromes (ACS), angina pectoris, 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 the Rote Liste 2014, for example, but not limited to, main groups 12 (antidiabetic drugs) or 86 (oncology drugs), and the Merck Index, 15th edition.

[0075] Examples of APIs for the treatment and / or prevention of type 1 or type 2 diabetes mellitus or complications associated with type 1 or type 2 diabetes mellitus include insulin, e.g., human insulin or a human insulin analog or derivative, glucagon-like peptide (GLP-1), a GLP-1 analog or a GLP-1 receptor agonist or an analog or derivative thereof, a dipeptidyl peptidase-4 (DPP4) inhibitor or a pharma- ceutically 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 residues can be either codable amino acid residues or other naturally occurring residues or purely synthetic amino acid residues. Insulin analogs are also referred to as "insulin receptor ligands". In particular, the term "derivative" refers to a polypeptide having a molecular structure that is formally derivable from the structure of a naturally occurring peptide, such as the 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 may be deleted and / or substituted by other amino acids, including non-codable amino acids, or amino acids, including non-codable amino acids, may be added to the naturally occurring peptide.

[0076] 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 in position B28 can be replaced by Asp, Lys, Leu, Val or Ala and in position B29 Lys can be replaced by Pro; Ala(B26) human insulin; Des(B28-B30) human insulin; Des(B27) human insulin and Des(B30) human insulin.

[0077] Examples of insulin derivatives are e.g. 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-myristoyl-LysB28ProB29 human insulin; B28-N-palmitoyl-LysB28ProB29 human insulin; B30-N-myristoyl-ThrB29LysB30 human insulin. B29-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.

[0078] Examples of GLP-1, GLP-1 analogs and GLP-1 receptor agonists include, for example, lixisenatide (Lyxumia®), exenatide (exendin-4, Byetta®, Bydureon®, GilaMonster (Gila 39 amino acid peptide produced by the salivary glands of the pancreatic monster), liraglutide (Victoza®), semaglutide, taspoglutide, albiglutide (Syncria®), dulaglutide (Trulicity®), r-exendin-4, CJC-1134-PC, PB-1023, TTP-054, langrenatide / HM-11260C (efpegrenatide), HM-15211, CM-3, GLP-1 Erigen, ORMD-0901, NN-9423, NN-9709, 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, ZP-DI-70, TT-401 (pegapamoditide), BHM-034, MOD-6030, CAM-2036, DA-15864, ARI-2651, ARI-2255, tirzepatide (LY3298176), bamadutide (SAR425899), exenatide-XTEN and glucagon-Xten.

[0079] An example of an oligonucleotide is, for example, mipomersen sodium (Kynamro®), a cholesterol-lowering antisense therapeutic for the treatment of familial hypercholesterolemia, or RG012 for the treatment of Alport Syndrome.

[0080] Examples of DPP4 inhibitors are linagliptin, vildagliptin, sitagliptin, denagliptin, saxagliptin, berberine.

[0081] Examples of hormones include pituitary or hypothalamic hormones or regulatory active peptides such as gonadotropins (follitropin, lutropin, chorion gonadotropin, menotropin), somatropin (somatropin), desmopressin, terlipressin, gonadorelin, triptorelin, leuprorelin, buserelin, nafarelin and goserelin, and their antagonists.

[0082] Examples of polysaccharides include glycosaminoglycans, hyaluronic acid, heparin, low molecular weight heparin, or very low molecular weight heparin, or derivatives thereof, or sulfated forms of the above polysaccharides, such as polysulfated forms, and / or pharmaceutically acceptable salts thereof.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 GF 20 (Synvisc®), sodium hyaluronate.

[0083] As used herein, the term "antibody" refers to an immunoglobulin molecule or an antigen-binding portion thereof. Examples of antigen-binding portions of an immunoglobulin molecule include F(ab) and F(ab')2 fragments that retain the ability to bind to an antigen. 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 functions and can fix 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, an antibody fragment, or a mutant that does not support binding to Fc receptors, 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 with crossover binding region orientation (CODV).

[0084] The term "fragment" or "antibody fragment" refers to a polypeptide (e.g., 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 an antigen. An antibody fragment may 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 invention include, for example, Fab fragments, F(ab')2 fragments, scFv (single-chain Fv) fragments, linear antibodies, monospecific or multispecific antibody fragments, such as bispecific, trispecific, tetraspecific and multispecific antibodies (e.g., diabodies, triabodies, tetrabodies), monovalent or multivalent antibody fragments, such as 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.

[0085] The term "complementarity determining region" or "CDR" refers to short polypeptide sequences within the variable regions of both the 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 the heavy and light chain polypeptides that are not CDR sequences and that are primarily responsible for maintaining the proper arrangement of the CDR sequences to allow antigen binding. Although the framework region itself typically does not directly participate in antigen binding, as is known in the art, certain residues within the framework region of a particular antibody can be directly involved in antigen binding or can affect the ability of one or more amino acids in the CDR to interact with the antigen.

[0086] 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).

[0087] Pharmaceutically acceptable salts of any of the APIs described herein are contemplated for use with the drug or medicament in the drug delivery device. Pharmaceutically acceptable salts include, for example, acid addition salts and base salts.

[0088] It will be understood by those skilled in the art that modifications (addition and / or deletions) may be made to the various components of the APIs, formulations, devices, methods, systems and embodiments described herein without departing from the full scope and spirit of the invention, and that the invention encompasses such modifications and any and all equivalents thereof.

[0089] Exemplary drug delivery devices may include needle-based injection systems as described in Table 1 of Section 5.2 of ISO 11608-1:2014(E). As described in ISO 11608-1:2014(E), needle-based injection systems may be broadly divided into multi-dose container systems and single-dose (partial or full discharge) container systems. The container may be a replaceable container or may be an integrated non-replaceable container.

[0090] As further described in ISO 11608-1:2014(E), a multi-dose container system may include a needle-based injection device with replaceable containers. In such systems, each container holds multiple doses and the size may be fixed or variable (pre-set by the user). Other multi-dose container systems may include a needle-based injection device with integrated non-replaceable containers. In such systems, each container holds multiple doses and the size may be fixed or variable (pre-set by the user).

[0091] As further described in ISO 11608-1:2014(E), the single-dose container system may include a needle-based injection device with a replaceable container. In one example of such a system, each container holds a single dose, which expels the entire deliverable amount (full expulsion). In a further example, each container holds a single dose, which expels a portion of the deliverable amount (partial expulsion). As also described in ISO 11608-1:2014(E), the single-dose container system may include a needle-based injection device with an integrated replaceable container. In one example of such a system, each container holds a single dose, which expels the entire deliverable amount (full expulsion). In a further example, each container holds a single dose, which expels a portion of the deliverable amount (partial expulsion).

[0092] Furthermore, it will be apparent to those skilled in the art that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Furthermore, it should be noted that any reference numbers used in the appended claims should not be construed as limiting the scope of the present invention.

[0093] In the following, embodiments of the driving mechanism and the injection device are described in detail by referring to the drawings. [Brief description of the drawings]

[0094] [Figure 1] FIG. 2 shows a perspective outer view of the injection device. [Diagram 2] 1 shows an isolated abstract view of the display member and the dosage member. [Figure 3a] FIG. 2 is an exploded perspective view of the inner body; [Figure 3b] FIG. 13 is an isolated perspective view of an alternative embodiment of an inner body. [Figure 4] 13 shows the interaction of the blocking member with the blocking structure prior to engagement when setting a dose. [Diagram 5] 5 shows the arrangement according to FIG. 4 with the indicator member rotated further in the direction of increasing dose. [Figure 6]6 shows the arrangement according to FIG. 5 and the interaction of the blocking member with the dose member. [Figure 7] 13 illustrates an arrangement in which the blocking member disengages the blocking structure when a minimum size therapeutic dose is set. [Figure 8] 1 shows the configuration of the device during dose dispensing. [Figure 9] The maximum dosage configuration of the display component is shown. [Figure 10] 1 shows a cross section through the indicator member and the inner body. [Figure 11] FIG. [Figure 12] 1 shows a first embodiment of a drive mechanism in an initial configuration. [Figure 13] 13 shows the drive mechanism according to FIG. 12 in the maximum set dose configuration. [Figure 14] FIG. 14 is an exploded view of the components of the drive mechanism according to FIGS. 12 and 13; [Figure 15] FIG. 13 is a perspective cutaway view of the interface between the inner body and the piston rod. [Figure 16] A cross-sectional view through the interface between the driver and the inner body is shown. [Figure 17] A perspective view of the outer circumference of the shaft portion of the dose member. [Figure 18] 13 shows a ratchet-like projection of the drive which matches with a correspondingly shaped receptacle on the outer periphery of the dose member. [Figure 19] FIG. 19 shows the configuration of FIG. 18 with the dose member and the drive part axially shifted. [Figure 20] FIG. 1 shows an exploded perspective view of the final dose nut. [Figure 21] 1 is a cross section through the interface of the final dose nut and the inner body. [Figure 22] 1 shows a final dose nut threadedly engaged with the threaded portion of the driver. [Figure 23] 1 shows a clutch between the indicator member and the dose member in an engaged state. [Figure 24] 24 shows the clutch according to FIG. 23 in a released configuration. [Diagram 25]13 shows the flexible arm of the indicator member engaging with the toothed profile of the dose member. [Figure 26] 1 shows the interengagement of the flexible arm with the toothed profile. [Figure 27] 1 shows an exploded view of another embodiment of an injection device that is of the reusable type. [Figure 28] 28 shows a dial sleeve of the display member according to FIG. 27. [Figure 29] 28 shows the proximal end of the display member according to FIG. 27. [Diagram 30] FIG. 28 is an exploded view of the distal drive portion according to FIG. 27. [Diagram 31] A separation diagram of the coupler is shown. [Diagram 32] 1 shows an exploded view of the final dose nut. [Diagram 33] 1 shows the proximal drive portion. [Diagram 34] 13 shows the clutch of the dose member. [Diagram 35] FIG. 13 is an exploded view of the proximal clicker portion. [Diagram 36] FIG. 13 is an exploded view of the distal clicker portion. [Figure 37] 1 shows the proximal portion of the dose member. [Figure 38] FIG. 13 is a partial cutaway view through the drive mechanism when assembled in the injection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0095] FIG. 1 shows a drug delivery device 1 in the form of an injection pen. The device has a distal end, shown as the left end in FIG. 1, and a proximal end, located on the right side of FIG. 1. Components or parts of the drug delivery device 1 are shown in more detail in FIG. 14, but without the blocking member or structure. The drug delivery device 1 comprises an outer housing part 10, an inner body 20, a piston rod 30, a driver 40, a final dose nut 50, an indicator member 60, a dose member 70, a cartridge 80, and a cap 120, i.e., a total of nine separate component parts. As shown in FIG. 14, a needle arrangement comprising a needle hub 2 and a needle cover 3 may be provided as an additional, replaceable component. The general concept and structure of the drive mechanism shown in FIGS. 12-26 are similar to the mechanism disclosed in WO 2014 / 033197 A1, which is incorporated herein by reference.

[0096] The outer housing part 10 is a generally tubular element having a distal part forming a cartridge holder 11 for receiving a cartridge 80 and a proximal part forming an outer body 12. In one embodiment, the outer housing part 10 is transparent and the outer body 12 is provided with an opaque layer 13. In FIG. 14, the opaque layer 13 covers most of the outer body 12 except for a transparent window 14. The cartridge holder 11 may be provided with an aperture 15. Furthermore, the cartridge holder 11 has at its distal end a thread 16 or the like for attaching the needle hub 2.

[0097] The inner body 20 is a generally tubular element having different diameter regions. The inner body 20 is received within the outer body 12 and is permanently fixed therein to prevent any relative movement of the inner body 20 with respect to the outer body 12. The shaft portion 20a of the inner body 20 is provided with male threads 21 on its outer surface. Additionally, the inner body 20 is provided with splines 22 on its inner surface, as shown in FIG. 21. As can be seen in FIG. 15, the inner body 20 has an internal thread 23 near its distal end.

[0098] The piston rod 30 is an elongated element with two external threads 31, 32 with overlapping opposite threads. One of these threads 31 engages with the internal thread 23 of the inner body 20. At the distal end of the piston rod 30, a disk-shaped bearing 33 is provided. As shown in FIG. 14, the bearing 33 can be attached to the piston rod 30 as a one-piece component through a predetermined break point. This separates the bearing 33 from the piston rod 30 in such a way that the bearing 33 remains fixed at the distal end of the piston rod 30 but allows relative rotation between the bearing 33 and the piston rod 30.

[0099] The driver 40 is a generally tubular element with different diameter regions. The distal region of the driver 40 has an external thread 41. The inner surface of the driver 40 has an internal thread 42, as shown in FIG. 22, which engages with one of the external threads 32 of the piston rod 30. The driver 40 surrounds the piston rod 30 and is at least partially located within the inner body 20. The driver 40 has at least one proximal opening 43 or slit, which will be described in more detail below. Furthermore, as shown in FIGS. 12 and 13, a resilient finger 44 is provided on the driver 40 by a U-shaped cut in the skirt of the driver 40. The finger 44 is capable of bending axially and engages the dose member 70. In addition, a flexible hinge-like projection 45, as shown in FIGS. 18 and 19, is provided on the driver 40 by a similar cut in the skirt of the driver 40. The projections 45 may be curved radially inwardly and are provided with lateral flaps 46. The projections 45 engage the splines 22 of the inner body 20.

[0100] Between the inner body 20 and the driver 40, a final dose nut 50 is provided. External ribs 51 of the nut 50 engage the splines 22 of the inner body 20. An internal thread 52 of the nut, as shown in FIG. 20, engages the external thread 41 of the driver 40. As an alternative, the interface between the nut 50 and the driver 40 can be provided with splines and ribs, and the interface between the nut 50 and the inner body 20 can be provided with a thread. As a further alternative, the nut 50 can be designed, for example, as a half nut. Furthermore, in the embodiment of FIG. 20, four rotational hard stops 53 are provided on the nut 50 for interaction with corresponding stops 47 on the driver 40 at the proximal end of the thread 41.

[0101] The indicator member 60 is a generally tubular element having an internal thread 61 which engages with the external thread 21 of the inner body 20. The indicator member 60 is thus sandwiched between the inner body 20 and the outer body 12. On the outer surface of the indicator member 60 a series of numbers is provided, e.g. printed. The numbers are arranged on a spiral line such that only one number or only a few numbers are visible through the window 14 of the outer body 12. As will be explained in more detail below, the indicator member 60 is attached to the drive 40 to prevent relative axial movement but allow relative rotation.

[0102] As shown in Figures 3 and 11, a zero unit rotation hard stop formed by stop wall 62 of indicator member 60 and corresponding stop surface 24 on inner body 20. This stop defines a distal zero dose position Z of indicator member 60 relative to inner body 20. Figures 3 and 11 also show a maximum dose (e.g., 80 units) rotation hard stop formed by stops 63a and 63b at the distal and proximal ends of indicator member 60 and corresponding stops 25a, 25b on the outer periphery or within thread 21 of inner body 20. This stop defines a proximal maximum dose position M of indicator member 60 relative to inner body 20. Thus, a user is prevented from dialing below zero units and above, for example, 80 units.

[0103] The dose member 70 has a proximal end with, for example, a serrated flange or a dose button 71 or an outer skirt to allow the user to easily grip and dial the dose member 70. A sleeve-like part 72 of the dose member 70, having a reduced diameter, extends in the distal direction 4 and is inserted into the driver 40 such that limited relative axial movement is permitted but relative rotation is prevented. This is achieved by a rib 73 on the sleeve-like part 72, which is guided in the proximal opening 43 of the driver 40, as shown in FIG. 13. A recess 73a is provided in the sleeve-like part 72 of the dose member 70, generally having the contour of the projection 45 and its side flap 46.

[0104] As shown in Figures 23 and 24, a clutch C is provided between the indicator member 60 and the dose member 70 by corresponding teeth 64 and 74. When the teeth 74 of the dose member 70 engage with the teeth 64 of the indicator member 60, the components are rotationally locked. The resilient fingers 44 of the driver 40 bias the dose member 70 in the proximal direction 5 of the device 1, i.e., towards engagement with the clutch teeth 64, 74. The clutch C can be released to allow relative rotation by axially shifting the dose member 70 with respect to the indicator member 60 against the bias of the fingers 44.

[0105] Furthermore, a dispensing clicker is provided by a flexible arm 65 on the indicator member 60 and an inner toothed profile 75 on the dose button 71 of the dose member 70. This clicker is shown in Figures 25 and 26.

[0106] Cartridge 80 contains a pre-filled, constricted cartridge reservoir 81, which may typically be made of glass. A rubber bung 82 or stopper is located at the proximal end of cartridge reservoir 81 and a pierceable rubber seal (not shown) is located at the other distal end. A crimped annular metal cap 83 is used to hold the rubber seal in place. Cartridge 80 is mounted in cartridge holder 11 with bearing 33 of piston rod 30 abutting bung 82.

[0107] 14 shows that a cap 120 is attached to the distal end of the device 1, thus covering the cartridge holder 11. The cap 120 may be removably snap-fit ​​onto the outer housing 10 and can be removed for use of the device 1.

[0108] In the following, the function of the disposable drug delivery device 1 and its components will be explained in more detail.

[0109] To use the device, the user must select a dose. In a starting (resting) state as shown in Figures 1 and 12, the display member 60 indicates to the user the dose that has been dialed in. The number of units that have been dialed in is visible through the dose window 14 in the outer body 12. Due to the threaded engagement between the display member 60 and the inner body 20, rotating the dose member 70 clockwise will cause the display member 60 to rotate out of the device and incrementally display the number of units to be delivered.

[0110] During dose setting, the dose member 70, the driver 40 and the indicator member 60 are rotationally locked together via the clutch teeth 64, 74. Furthermore, the dose member 70, the driver 40 and the indicator member 60 are axially coupled such that these three components rotate out of the outer housing 10 during dose setting.

[0111] Clockwise rotation of the dose member 70 rotates the driver 40, which advances along the piston rod 30, which remains fixed throughout the dial setting. The protrusions 45 and splines 22 form a clicker mechanism that provides tactile and audible feedback to the user when dialing a dose. This clicker arrangement has the additional function of defining a discrete position of the indicator member 60 when dialing, and providing a way to lock the rotation of the driver 40 and dose member 70 during dosing. During dial setting, and thus during dose setting, the dose member 70 is in an axial position relative to the driver 40, such that the pocket or recess 73A is located radially inward of the protrusions 45. Thus, the protrusions 45 are able to bend radially inwardly to overcome the splines 22, thereby providing tactile and audible feedback to the user. FIG. 16 shows a flexible protrusion arm 45 located between splines 22 spaced apart, for example, by 15°.

[0112] At a maximum settable dose of 80 units, the stop features 63a, 63b and 25a, 25b shown in Figures 3 and 11 engage and prevent further dialing. The final dose nut 50 provides the functionality of recording the total number of units dispensed. The nut 50 locks the device 1 at the end of its life so that no more medication can be dialed or dispensed by the user. The final dose nut 50 and the driver 40 are connected via threaded interfaces 41, 52 as described above. Furthermore, the final dose nut 50 is assembled into the spline 22 such that the nut 50 and the inner body 20 are permanently rotationally locked together as shown in Figure 21. Rotation of the driver 40 during dialing advances the nut 50 along the threads 41 of the driver 40. The nut 50 is always free to slide axially within the inner body 20, which allows the nut 50 to advance. The varying pitch towards the end dose, shown in FIG. 22, accelerates the advancement of the nut 50 axially towards the end of life lockout condition.

[0113] At the end of life condition, the stop features 53 of the final dose nut 50 contact corresponding features 47 on the driver 40. The splined contact with the inner body 20 reacts to any torque transmitted by these stop features 47.

[0114] Once the desired dose has been dialed in, the device 1 is ready to dispense a dose. This essentially entails pressing the dose member 70, which results in the clutch teeth 64, 74 being disengaged. As mentioned above, when dialing in a dose, the dose member 70 is "biased out" and the clutch features 64, 74 are engaged which rotationally lock the driver 40, dose member 70 and indicator member 60 together, as shown in FIG. 23. Pressing the proximal button portion of the dose member 70 disengages the clutch features 64, 74 as shown in FIG. 24, allowing relative rotation between the indicator member 60 and the dose member 70. In all conditions, the driver 40 and dose member 70 are rotationally locked together by the engagement of the rib 73 with the opening 43. Thus, with the clutches 64, 74 disengaged, i.e., with the dose member 70 pressed or pushed distally, the dose member 70 and the drive member 40 are rotationally locked together, while the dose member 70, the drive member 40 and the indicator member 60 remain axially coupled.

[0115] At the same time, the relative axial movement of the dose member 70 with respect to the driver 40 results in the pocket or recess 73 shifting with respect to the projection 45. Thus, the projection 45 is prevented from bending inwardly because the flap 46 rests on the non-recessed area of ​​the sleeve portion 70a of the dose member 70. A comparison of Figs. 18 and 19 illustrates such actuation of the lockout feature that prevents the flexible projection arm 45 from overcoming the spline 22 when the dose member 70 is pushed. In this condition, the driver 40 and the dose member 70 are rotationally constrained with respect to the inner body 20 and therefore any rotation with respect to the outer housing 10 is prevented when the spline 22 is axially aligned with the device as shown in Fig. 16. An alternative embodiment having a twisted spline 22 is also contemplated. In that case, the twisted spline is responsible for inducing rotation of the driver as it is subject to a distally directed displacement during dose dispensing.

[0116] Once the desired dose is dialed in, the dose member 70 can be depressed, driving the piston rod 30 forward and dispensing the drug from the cartridge 80. The mating thread interaction between the piston rod 30, the driver 40 and the inner body 20 provides a mechanical advantage, for example, of 2:1 in the example shown. While the initial and novel device in a zero dose configuration is shown in Figure 12, Figure 13 shows the device 1 with 80 units dialed in prior to pressing the dose member 70.

[0117] During dose dispensing, a dispense clicker with which the dose member 70 and indicator member 60 are associated is activated. The dispense clicker provides audible feedback to the user that drug is being dispensed. As shown in Figures 25 and 26, the interaction between a flexible arm 65 on the indicator member 60 and a toothed profile 75 on the button flange 71 provides this dispense click. Relative rotation is only possible in one direction. This occurs when the components are decoupled during dispensing, producing a click sound for each unit.

[0118] In Figures 2-11 the minimum dose mechanism or minimum dose function of the drive mechanism is generally described. As is evident from a comparison of Figures 2 and 12, the shape of the dose member 70 shown in Figure 2 has been slightly altered from the overall shape of the dose member 70 shown in the embodiment of Figures 12-26. However, the overall functionality of the dose member 70 as well as its interaction with all other components, in particular with the indicator member 60 and the drive 40, is at least similar or even identical to the interactions described above in relation to Figures 12-26. In the illustration according to Figures 2-11 the piston rod 30, the drive 40 and the final dose nut 50 have been omitted for clarity.

[0119] The inner body 20 comprises an elongated shaft 20a as shown in FIG. 3. Along the outer circumference of the elongated shaft, an outer thread 21 is provided which is threadably engaged with a radially inwardly extending thread feature or inner thread 61 of an indicator member 60 as shown in FIG. 11. Additionally, the elongated shaft 20a comprises a blocking structure 26. In this embodiment, the blocking structure 26 comprises a blocking thread 27 extending axially between interlocking portions of the outer thread 21. The blocking structure 26, and thus the blocking thread 27, terminates at distal ends 26a, 27a in the distal direction 4. The blocking structure 26 terminates at proximal ends 26b, 27b in the proximal direction 5. The blocking thread 27 thus terminates at a proximal end 27b in the proximal end direction 5. As shown in FIG. 3a, the distal and proximal ends 27a, 27b of the blocking thread 27 are located within the axial extension of the outer thread 21. The axial offset between the blocking thread 27 and the outer thread 21 is approximately half the pitch of the outer thread 21. The lead of the blocking thread 27 is substantially equal to or exactly the same as the lead of the outer thread 21.

[0120] As shown in Figure 2, the indicator member 60 comprises a step-down portion at its proximal portion 60b which is housed within a sleeve-like dose member 70 having a tubular shaft 70a extending in a distal direction 4 from a dose dial or dose button 71. The proximal portion 60B and the dose member 70 are selectively rotationally engageable by means of a clutch C, as will be described in relation to Figures 23 and 24. The proximal portion 60b of the indicator member 60 is not further shown in Figures 4 to 11 for the sake of simplicity.

[0121] The indicator member 60 comprises at least one blocking member 66 as shown in Fig. 4. The blocking member 66 comprises a flexible arm extending in a tangential direction and coincides with the side wall 60a of the indicator member 60 when viewed in an axial projection. The blocking member 66 comprises a base portion 66c, by means of which the blocking member 66 is joined to the side wall 60A of the indicator member 60. Between the blocking member 66 and the axially adjacent side wall portion 60a, a tangential slit 66a or a respective gap is provided, so that the blocking member 66, in particular its free end 66b, can bend or deform freely in the axial direction (z). The side wall 60a of the indicator member 60 thus comprises a recess, large enough to support the blocking member 66 and to allow bending or displacement of the blocking member 66 towards the distal or proximal direction.

[0122] As shown in FIG. 11, the free end 66b of the blocking member 66 comprises a projection 67 extending radially inward. The projection 67 has a rib-like shape and extends substantially parallel to the internal thread 61. The projection 67 is particularly adapted to mate or engage with the blocking thread 27 on the outer periphery of the inner body 20. As can be seen from FIGS. 4 and 5, the blocking member 66 comprises an L-shaped structure having a long side extending tangentially and a short side extending axially in the proximal direction. The proximal end of the free end 66b of the blocking member 66 is provided with two fork-shaped abutment portions 68 adapted to axially engage with the distally facing abutment portions 76 of the dose member 70, as shown in FIG. 6. The abutment portions 68 are arranged radially outward of a support surface 69 extending proximally from the proximal end of the abutment portions 68. As shown in various configurations in Figures 2 and 6, the support surface 69 is restrained by the inwardly facing side wall of the dose member 70 so as to provide effective axial guidance between the axial abutments 68, 76 of the corresponding blocking member 66 and dose member 70.

[0123] Distal ends 26a, 27a are axially spaced from stop 24 at the distal end of outer thread 21 by the length of indicator member 60 from that distal end to at least one blocking member 66, plus additional axial space which defines the size of the variable or titrated dose range. That is, distal end 27a of blocking screw 27 defines the maximum size of a variable titrated dose, while the axial location of proximal end 27b of blocking screw 27 defines the minimum value of a fixed dose that may be set and subsequently dispensed by injection device 1.

[0124] In general, the blocking member 66 may assume different axial positions on the inner body 20 depending on the amount of relative rotation of the indicator member 60 with respect to the inner body 20. In an initial configuration, before setting a dose or when the drive mechanism is in a zero dose configuration, the indicator member 60 is in its most distal position on the inner body 20. This position is referred to as the distal zero dose position Z. On the other hand, the most proximal position that the indicator member 60 assumes on the inner body 20, i.e. when the maximum dose is selected, is referred to as the proximal maximum dose position M.

[0125] In the illustrated embodiment, the axial position of the distal end 27a of the blocking screw 27 on the inner body 20, i.e. the position defining the maximum size of the variable titration dose, is offset in the proximal direction 5 from the distal zero dose position Z by 20%-30%, e.g. up to 25%, of the axial distance between the distal zero dose position Z and the proximal maximum dose position M. However, this position may also be located closer to the distal zero dose position Z or closer to the proximal maximum dose position M, e.g. between 10%-60% of the axial distance between the distal zero dose position Z and the proximal maximum dose position M. Typically, the indicator member 60 is rotatable relative to the inner body 20 over a predetermined number of rotations, e.g. 4 or 5 complete rotations corresponding to a relative rotation of 1440° or 1800° between the distal zero dose position Z on the inner body 20 and the proximal maximum dose position M on the inner body 20.

[0126] In the initial configuration, prior to setting a dose or when the drive mechanism is in a zero dose configuration Z, the blocking member 66, and in particular its projection 67, is not yet engaged with the blocking screw 27, as shown in Figure 4. In this initial configuration, the blocking member 66, and in particular its projection 67, is located distally from the distal end 27a of the blocking screw 27. The dose member 70 is therefore displaceable in the distal direction to disengage the clutch C and initiate the dispensing procedure as described above.

[0127] When the indicator member 70 is further rotated in the dose-increasing direction relative to the inner body 20, the projection 67 of the blocking member 66 engages the chamfered distal end 27a of the blocking screw 27. Thanks to the chamfer 27c, the projection 67 undergoes a slight displacement in the proximal direction 5, whereby the blocking member 66 pivots so that its free end is in the proximal direction 5. In this way, the axial size of the gap 66a at least in the region of the free end section 66b increases and the abutment 68 of the free end section 66b approaches the corresponding abutment 76 of the dose member 70. As the projection 67 has passed the chamfer 27c, the projection 67 is biased in the proximal direction 5 by the proximally facing edge 27e of the blocking screw 27.

[0128] In this configuration, the abutment 68 of the free end 66b of the blocking member 66 axially abuts or is very close to the abutment 76 of the dose member 70, thereby preventing and blocking distal displacement of the dose member 70 relative to the inner body 20 and the indicator member 60. Thus, the clutch C remains locked and the device 1 cannot be switched to the dispensing mode. As long as the blocking member 66 is engaged with the blocking screw 27 or the blocking structure 26, this axial abutment and blocking configuration between the blocking member 66 and the dose member 70 is maintained. Thus, the blocking member cannot bend because it is engaged with the blocking screw. Because the dose member abuts the blocking member, the dose member also cannot be displaced distally to initiate dispensing.

[0129] When the flexible blocking member 66 is axially engaged with the proximally facing edge 27e of the blocking screw 27, any axially directed force transmitted through the dose member 70 is directly transmitted to the inner body 20 through the blocking member 66. Due to this relatively short and rather direct load path between the dose member 70 and the inner body 20, a robust and powerful blocking action can be provided. In this blocking configuration, there is essentially little flexibility that can confuse a user. When the blocking member abuts the blocking screw 27 axially proximally and also abuts or is close to the dose member 70 axially distally, the blocking member is axially pinched between the dose member 70 and the inner body 20. In this way, the axial blocking of the dose member 70 has relatively little play or looseness that can confuse a user.

[0130] Only upon further dialing of the indicator member 60 in the dose increase direction does the blocking member 66 disengage the blocking structure 26, i.e. the blocking screw 27, causing the blocking member 66 to relax and return to its initial unbiased state, as shown in Figure 7, with the projection 67 having just passed the proximal end 27b of the blocking screw 27. As a result, the blocking member 66, and in particular its free end section 66b, is displaceable or flexible in the distal direction 4 under the influence of the dose member 70 advancing distally, or simply by relaxation to its natural unbiased state.

[0131] In Figure 8 a configuration is shown in which the drive mechanism has dispensed several units such that the remaining amount of drug to be dispensed is less than the minimum intended dose size. When the drive mechanism performs a dose dispensing procedure, the blocking member 66 is in its release position R and is then curved in a distal direction due to the distally directed displacement of the dose member 70 in the dose dispensing position D. As the indicator member 60 rotates in the dose reduction direction during dose dispensing, the blocking member 66 passes along the distal side of the blocking screw 27d as shown in Figure 8.

[0132] When the protrusion 67 enters the blocking screw 27 from the proximal side during dose dispensing, it is located near the distally facing edge 27d of the blocking screw 27. Even if the dispensing procedure is to be interrupted in a configuration as shown in Fig. 8, the blocking member 66 is effectively prevented from pivoting or bending in the proximal direction 5. Thus, if the dose dispensing procedure is to be continued, the dose member 70 is not prevented by the blocking member from being displaced to its dose dispensing position D. Even if there is axial abutment between the blocking member 66 and the dose member before the dose member 70 reaches the dose dispensing position D, the blocking member 66 is free to displace at least slightly in the axial distal direction 4 and resume dispensing.

[0133] In this state, the clutch C between the dose member 70 and the indicator member 60 is opened or released and dispensing can continue. In other words, the blocking member 66, and in particular its free end section 66b, remains trapped distal to the blocking screw 27. The user can then resume dispensing the dose even if the indicator member 60 is in a position below the predetermined minimum dose value.

[0134] 2-11, only a single blocking member 66 is shown, it is contemplated that two or more blocking members 66 may be provided around the circumference of the indicating member 60. If more than one blocking member is provided, an equivalent number of blocking screws will be required.

[0135] In Figure 9 the maximum dose configuration is shown, where a maximum dose stop 63b located on the tangentially facing side wall of the blocking member 66 abuts tangentially against a correspondingly shaped stop 25b on the inner body.

[0136] The configuration of the inner body 20 and the indicator member 60 includes two pairs of mutually corresponding stops. As shown in FIG. 3, the inner body 20 includes a distally located maximum stop 25a and a proximally located maximum stop 25b. Both stops extend radially outward from the circumference of the elongated shaft 28 of the inner body 20 and include a tangentially facing abutment surface. The respective abutment surfaces coincide with a radial plane and an axial plane. The indicator member 60 also includes at least one proximal maximum dose stop 63b and at least one distal maximum dose stop 63a, as shown in FIG. 11. In the embodiment shown in FIG. 11, two distal maximum dose stops 63a are provided that mate and engage with correspondingly shaped dose stops 25a on the inner body 20. The mutually corresponding stops 25a, 25b, 63a, 63b are engaged simultaneously when the indicator member 60 reaches the maximum dose configuration, i.e., when the indicator member 60 is at the proximal maximum dose position M. The interengaging stops 25 a , 25 b , 63 a , 63 b then prevent further dose increment rotation of the indicating member 60 relative to the inner body 20 .

[0137] Generally, it is sufficient to provide only one pair of maximum dose stops, for example 25a, 63a. The two pairs of mutually corresponding maximum dose stops 25a, 25b, 63a, 63b reinforce each other. As a result, the load expected on the respective blocking member when the blocking configuration is reached is lower than if only one pair of mutually corresponding stops, for example the pair 25a, 63a, is implemented. This has the advantage that the stop features can be designed rather smaller than would otherwise be the case. This not only saves space, but also facilitates the assembly of the device when screwing the indicator member 60 into the inner body 20. The relatively small stops 25a, 25b, 63a, 63b are more likely to be broken or damaged during assembly.

[0138] Because the minimum and maximum deliverable dose volumes depend only on the geometry and overall design of the inner body 20, its blocking screw 27, and the location of the maximum dose stops 25a, 25b, different device types can be easily constructed for a variety of applications. Also, by varying only one component, different dose sizes can be easily implemented. Because the minimum and maximum dose features do not protrude beyond the basic envelope of the inner body, it is also easy to implement the minimum and maximum dose functions with a wide range of different device configurations using common automated assembly equipment.

[0139] In Fig. 3b, an alternative embodiment of the inner body 220 is shown having a blocking structure 26 with a blocking screw 227 slightly different from the blocking screw 27 shown in Fig. 3a. The blocking screw 227 has several recesses 227a, 227b, 227c, 227d or interruptions that define discrete dose sizes that are exclusively dispensed by the respective drive mechanisms. The blocking screw 227 extends mostly along the axial extension of the shaft 20a. Only when the position of the blocking member 66 axially and / or tangentially overlaps with the position of one of the recesses 227a, 227b, 227c, 227d, the dose member 70, and therefore the blocking member 66, can be displaced in the distal direction 4 to initiate the dispensing operation.

[0140] The tangential and axial positions of the recesses 227a, 227b, 227c, 227d define the discrete dose sizes into which doses can be dispensed exclusively. By simply modifying the inner body 20 with the blocking screw 27 or replacing it with another inner body 220 with a different blocking screw 227, the injection device can be converted from a device capable of individually setting doses of variable sizes to a fixed dose device or vice versa.

[0141] The recesses 227a, 227b, 227c, 227d are arranged such that two adjacent recesses are spaced from each other by 10% to 20%, e.g. 12.5%, of the axial distance between the distal zero dose position Z and the proximal maximum dose position M. This corresponds, e.g., to 10 units.

[0142] While the embodiment shown in Figures 12 to 26 relates to a disposable injection device, the alternative embodiment according to Figures 27 to 38 relates to a reusable injection device. The minimum dose feature described with reference to Figures 1 to 11 is not further shown in Figures 12 to 38 solely for the sake of simplicity.

[0143] Components of the reusable embodiment shown in Figures 27-38 that are the same or similar compared to the embodiment of Figures 12-26 are indicated with the same or similar reference numbers unless otherwise stated. Where components have changes compared to the single-use embodiment, similar components are assigned reference numbers incremented by 100. The general concept and structure of the drive mechanism shown in Figures 27-38 is similar to the mechanism disclosed in WO 2014 / 033195 A1, which is incorporated herein by reference. The implementation and adaptation of the minimum dose feature described above in relation to Figures 1-11 applies equally to the embodiment of Figures 27-38.

[0144] In this embodiment, the drive 140 is a generally tubular element having three components 141, 142, 143 in the illustrated embodiment, which are shown in more detail in Figures 27, 30, 31 and 33. The drive 140 comprises a distal drive sleeve 141, a proximal drive sleeve 142 and a coupler 143. The distal drive sleeve 141 engages the piston rod thread 32 to drive the piston rod 30 through the inner body 20 during dose delivery. The distal drive sleeve 141 is also permanently connected to the coupler 143, which is releasably engaged to the proximal drive sleeve 142 via a reset clutch feature. The two halves of the drive sleeves 141, 142 are rotationally and axially connected during dial setting and dispensing, but are rotationally decoupled during device reset to allow rotation relative to each other.

[0145] The proximal drive sleeve 142, shown in Figure 33, supports the clicker 100 and sleeve clutch 90 components and transmits rotational movement from the dose member 70 to the coupler 142 and distal drive sleeve 141. Teeth features 147 located at the distal end of the proximal drive sleeve 142 engage reset clutch features on the coupler 143 during dial setting and dispensing to connect the two halves of the drive sleeve. During reset, the teeth 147 are disengaged.

[0146] There are several splines on the outer surface of the proximal drive sleeve 142 that engage with the distal clicker portion 101 to prevent relative rotation during dialing and dispensing. Further splines located in a central region of the proximal drive sleeve 142 engage components of the clutch 90. These may be configured to be non-rotationally symmetrical so that the various clicker components cannot be accidentally assembled upside down.

[0147] The proximal portion of the proximal drive sleeve 142 has four arms or fingers 148. As can be seen in FIG. 33, there is a hook-like bearing surface 149 on the underside of a flange segment at the end of the flexible fingers 148. The flexible fingers 148 are separated by gaps or slots that allow space for the dose member 70 to snap into the clutch 90 and also allow the fingers to flex inwardly during assembly of the proximal drive sleeve 142 to the dial sleeve 162. After assembly, the hooks 149 receive a rebound force from the spring 103 to hold the proximal drive sleeve 142 against the dial sleeve 162.

[0148] During dispensing, the dose member 70, via the clutch 90 and clicker components, pushes down on the spring 103 which acts via the coupler 143 on the proximal drive sleeve 142 which in turn applies an axial load to the dial sleeve 162 via the bearing surface 149. This axial load drives the dial sleeve 162, and therefore the number sleeve 161, back along the helical threads of the inner body 20 into the body of the device until the zero dose stop surface 62 on the number sleeve 161 contacts the inner body 20.

[0149] Coupler 143, shown in FIG. 31, rotationally couples the two halves of drive sleeve 140 together during dial setting and dispensing, while allowing them to be decoupled during reset. Coupler 143 is also required to transfer the final dose stop load from proximal drive sleeve 142 to distal drive sleeve 141. There are two sets of teeth within coupler 143 for engaging teeth 146 and 147, respectively. Coupler 143 is snap-fit ​​onto distal drive sleeve 141, allowing limited relative axial movement with respect to proximal drive sleeve 142.

[0150] The indicator member 160 is a generally tubular element made up of a number sleeve 161 and a dial sleeve 162, the two components being snap-fit ​​together and axially and rotationally constrained during assembly, thus functioning as a single piece. The dial sleeve 162 is assembled to the number sleeve 161 such that no relative movement is permitted once assembled. The parts are made as separate components to allow both molding and assembly. Also, the number sleeve 161 is preferably white to provide contrast against, for example, black dose numbers, although the color of the dial sleeve 162 may be selected for aesthetic appeal or to distinguish drug types as the case may be.

[0151] At the proximal end, the dial sleeve 162 has internal clutch features 165 which engage the clutch component 90 during dialing and disengage from the clutch during dispensing. These clutch features 165 rotationally lock the dial sleeve 162 to the clutch 90 when the zero and maximum dose stops are engaged during dialing. When the dose member 70 is depressed, these clutch features are disengaged allowing the dial sleeve 162 and number sleeve 161 to spin back to the zero unit start position while the clutch 90 is allowed to move axially.

[0152] The dial sleeve 162 rotates out during dialing through engagement with the clutch 90 and number sleeve 161, and rotates back during dispensing under axial force exerted by the proximal drive sleeve 142 against a flange-like bearing surface 166 on the proximal end of the dial sleeve as shown in Figure 29. This bearing surface 166 engages the flexible arm 148 of the proximal drive sleeve 142 during dispensing. When the maximum dose is dialed in, two diametrically opposed surfaces 167 may engage the outer body 10 to form a maximum dose stop surface.

[0153] The central sleeve-like portion of the dose member 70 is provided with four arms 173, each having a hook-like snap feature 174 at its distal end. The arms 173 form a splined surface that engages with the clutch 90 to transfer torque from the dose member 70 through the clutch to the dial sleeve 162 and the proximal drive sleeve 142. The snap features 174 are designed with angled undercut surfaces to engage apertures in the clutch 90 and maintain engagement when an axial load is applied to withdraw the dose member 70 from the pen body 10. The spaces between the arms 173 define pockets that provide clearance for the flexible arms 148 of the proximal drive sleeve 142 to slide freely relative to the dose member 70 and the clutch 90 as the dose member 70 is pushed and released during dose dispensing.

[0154] A tubular clutch 90 is provided between the indicator member 160 and the dose member 70. The clutch is fixed relative to the dose member 70 to retain it and moves axially therewith relative to the proximal drive sleeve 142 to disengage the clutch teeth 95 from the dial sleeve clutch teeth 165 when the dose member 70 is depressed during dispensing. The clutch also transfers torque from the dose member 70 to the proximal drive sleeve 142 and transfers the dial settings and zero and maximum dose stop loads from the dose member 70 via the clutch teeth to the dial sleeve 162 and number sleeve 161.

[0155] Drive sleeve splines 91 provided on the inner surface of the clutch engage the proximal drive sleeve 142. The distal end face is provided with clutch biasing teeth 92 which mate with similar teeth 109 on the proximal clicker portion 102 to ensure that in the uninhibited button-out position (dose dialed), the clutch is rotationally biased against the proximal clicker portion 102 under the biasing action of the clutch spring 103, thus ensuring that the dose number shown on the display member is correctly and clearly displayed to the user. The teeth 92 are shallow in height to prevent the proximal clicker portion 102 from engaging the splines on the proximal drive sleeve 142 during dialing. Four snap apertures 93 serve to retain the snap features 174 of the dose member 70. The clutch has splines 94 near its proximal end which, at the end of dispensing, lock the dose member 70 in the depressed state to the inner body 20, preventing the user from rotating the dose member 70 below the zero dose position.

[0156] The clutch teeth 95 engage clutch teeth 165 on the dial sleeve 162 to rotationally couple the dose member 70 to the number sleeve 161 via a clutch. During dispensing, the clutch 90 moves axially, which disengages the clutch teeth 95 and releases the dial sleeve 162 to rotate back into the device while the clutch 90, and therefore the drive 140, moves axially to dispense a dose.

[0157] The clicker 100 comprises a distal clicker portion 101, a proximal clicker portion 102 and a spring 103. The spring 103 biases the dose member 70 so that at the end of the dose, the dose member 70, particularly the proximal button portion thereof, pops out to re-engage the clutch 90 with the dial sleeve 162, ready for dialing. Furthermore, the spring 103 provides a spring force to the clicker components to provide audible and tactile feedback to the user, and also provides a detent position for the number sleeve 161. Additionally, the spring 103 holds the drive sleeve halves 141, 142 in rotational engagement during dialing and dispensing, while allowing them to disengage during device reset.

[0158] The distal clicker portion 101 is permanently splined to the proximal drive sleeve 142 and engages the proximal clicker portion 102, which is then splined to the inner body 20. During dial setting, as the drive sleeve rotates relative to the inner body 20, the two clickers 101, 102 rotate relative to each other under the compressive force of the clutch spring 103. This force, in combination with clicker teeth formed on the end face of each clicker, provides an audible click and also a detent dial position.

[0159] During dispensing, the two clickers 101, 102 are pushed together under the axial dispensing load applied by the user to the dose member 70, which prevents relative rotation between the proximal drive sleeve 142 and the inner body 20 and pushes the piston rod 30 forward to deliver the dose. The splines 104 on the inner bore always rotationally couple the distal clicker part 101 to the proximal drive sleeve 142, but allow free axial movement when the dose member 70 is pushed during dosing and when the two clickers rest on top of each other during dial setting. The profiles of the clicker teeth 105, 106 on both the distal clicker part 101 and the proximal clicker part 102 are identical and rest on top of each other under a compressive load from the spring 103 during dial setting.

[0160] The proximal clicker portion 102 is permanently splined to the inner body 20 by an external spline 107, which prevents relative rotation with respect to the inner body 20 both during dialing and dispensing, provides a clicking sound during dialing, and locks the proximal drive sleeve 142 against rotation during dispensing. In addition, when the dose member 70 is pushed in, the cylindrical spline 108 also rotationally couples the proximal clicker portion 102 to the proximal drive sleeve 142, which prevents the user from dialing more than 80 units with the dose member 70 pushed in. In addition to the primary clicker teeth 106, the proximal clicker portion 102 has clutch biasing teeth 109 on the opposite end face. These teeth mate with similar teeth 92 on the clutch 90 to ensure that in the uninhibited buttoned-out position (dose dialed in), the clutch is rotationally biased by the proximal clicker portion 102 under the biasing action of the clutch spring 103.

[0161] The cartridge biasing spring 110 is assembled as two overlapping components, a lower first component and an upper second component. This spring combination functions to apply an end load to the cartridge 80 at the extremes of the tolerances to bias the cartridge 80 forward onto the end face of the ferrule in the cartridge holder 11. This ensures that the friction between the needle cannula and the septum of the cartridge 80 does not move axially relative to the cartridge holder 11 when the user removes and installs the needle. The biasing spring 110 also functions to provide a force that the user must resist to connect the cartridge holder 11, which may be added to the tactile feedback of the bayonet joint between the cartridge holder 11 and the inner body 20. The spring 100 also functions to eject the cartridge holder 11 if it is not properly installed in a secure position, highlighting this mistake to the user.

[0162] During dose setting, the dose member 70, the driver 140 and the indicator member 160 are rotationally locked together via the clutch 90. Furthermore, the dose member 70, the driver 140 and the indicator member 160 are axially coupled. Thus, these three components rotate out of the outer body 12 during dose setting. Clockwise rotation of the button dose member 70 rotates the driver 140 on a helical path, which advances the driver along the piston rod 30, which remains fixed throughout the entire dial setting. The clicker arrangement 100 provides tactile and audible feedback to the user when dialing the dose. At the maximum settable dose of 80 units, the stop features 12 and 67 engage, preventing further dialing.

[0163] Once the desired dose has been dialled in, the device 1 is ready to dispense a dose. This requires pressing the proximal button portion of the dose member 70, which results in the clutch 90 disengaging from the dial sleeve 162, thus allowing relative rotation between the indicator member 160 and the dose member 70. In all conditions, the drive 140 and the dose member 70 are rotationally locked together by the engagement of the arm 173 with the finger 148, and by the splines 91 engaging with corresponding splines on the proximal drive sleeve 142. Thus, with the clutch 90 disengaged, the dose member 70 and the drive 140 are rotationally locked together, and the dose member 70, the drive 140 and the indicator member 160 remain axially coupled.

[0164] When dispensing a dose, the dose member 70 and clutch 90 move axially relative to the mechanism compressing the clutch spring 103. Because the proximal clicker part 102 is splined to the inner body 20 and axial loads passing through the clicker teeth 105, 106 rotationally lock the distal clicker part 101 to the proximal clicker part 102, the drive sleeve 140 and clutch 90 parts of the mechanism are forced to move axially while the dial sleeve 162 and number sleeve 161 are free to rotate back into the outer housing 10. The mating threaded interaction between the piston rod 30, the drive 140 and the inner body 20 provides a mechanical advantage of, for example, 2:1.

[0165] In other words, the axially advancing drive 40 rotates the piston rod 30 which advances due to the threaded engagement between the piston rod 30 and the inner body 20. During dose dispensing, the dispense clicker 168, 71 with which the dose member 70 and the indicator member 160 are associated is activated. The dispense clicker provides audible feedback to the user that medication is being dispensed.

[0166] When the dose is dispensed and the user removes force from the end of the dose member 70, the clutch spring 103 pushes the dose member 70 proximally, re-engaging the teeth 165 and 95 between the clutch and the dial sleeve.

[0167] Resetting the device begins with removing the cartridge holder 11 and replacing the empty cartridge with a filled cartridge 80. When the cartridge holder 11 is reinstalled, the bung of the new cartridge 80 contacts the bearing 33, thus pushing the piston rod 30 back into the housing. Initially, the piston rod 30 threads into the inner body 20, thereby axially disengaging the coupler 143 from the proximal drive sleeve 142 against the biasing force of the spring 103. Once disengaged, the coupler 143 begins to rotate freely together with the distal drive sleeve 141, and continues to rotate as the cartridge holder 11 moves axially into engagement with the inner body 20. Thus, the distal drive sleeve 141 rotates relative to the proximal drive sleeve 142, which is still rotationally constrained within the inner body 20, as the clicker parts 101 and 102 are forced together by the compression spring 103.

[0168] Rotation of the distal drive sleeve 141 resets the final dose nut 50 to its (distal) starting position. The final dose nut 50 is threadably engaged with the external threads 144 of the distal drive sleeve 141. When the cartridge holder 11 is coupled to the inner body 20, the mechanism retracts due to the bayonet arrangement which allows re-engagement of the proximal drive sleeve 142 with the coupler 143 and thus with the distal drive sleeve 141.

[0169] It should be noted here that the minimum dose functionality described in relation to Figures 1-11 can be similarly implemented or is actually implemented in the reusable device described in relation to Figures 27-38.

[0170] The indicator member 160, as implemented with the injection device 1 and with the drive mechanism according to Figs. 27-38, comprises a number sleeve 161 and a dial sleeve 162. The dial sleeve 162 is provided with a ratchet arm 168 near its proximal end and further has a bearing surface 166 and a clutch feature 165 for selectively engaging the teeth 95 of the clutch 90. The number sleeve 161 and the dose sleeve 162 are permanently engaged with each other. The distal section of the dial sleeve 162 is located inside the proximal section of the number sleeve 161. Thus, the side wall 181 of the number sleeve 161 surrounds at least a distal portion of the side wall 182 of the dial sleeve 162.

[0171] Mutually corresponding recesses 184 and protrusions 185 are provided on the radially overlapping portions of the number sleeve 161 and the dial sleeve 162. In one embodiment, at least two recesses are provided near the proximal end of the number sleeve 161, which engage and receive radially outwardly extending protrusions on the distal section of the side wall of the dial sleeve 162. In this way, a snap-fit ​​engagement between the number sleeve 161 and the dial sleeve 162 is obtained. Thus, the dial sleeve 162 is permanently rotationally and axially locked to the number sleeve 161 and vice versa.

[0172] In one embodiment, two blocking members 66 are provided at the proximal end of the number sleeve 161. The radially inwardly extending projections 67 of the blocking members 66 each extend through an aperture in the side wall of the dial sleeve 162. Thus, the projections 67, and thus the blocking members 66, extend radially through the side wall of the dial sleeve 162 for direct engagement with the blocking structure 26 on the outer periphery of the inner body 20. The longitudinal or axial extension of the aperture is sufficient to permit and support axial displacement of the blocking members 66 relative to the dial sleeve 162 and relative to the number sleeve 161 when in the release configuration R.

[0173] In the released configuration R, the protrusion 67 of the blocking member 66 is located distally from the blocking structure 26 and therefore distally from the blocking screw 27. In other words, the blocking member 66 may be aligned with an intersection or gap of the blocking screw 27. In the released position or configuration R, the dose member 70 is displaceable in the distal direction 4, thereby biasing the flexible blocking member 66 in the distal direction.

[0174] In blocking position B, the projection 67 of the blocking member 66 is located proximally of the blocking structure 26. Here, the distal edge 67d of the projection 67 faces the proximal edge 27e of the blocking screw 27. In this blocking position B, the blocking member 66 abuts axially against the blocking structure 26. The blocking member 66 cannot be displaced in the distal direction 4. A distally directed dispensing force acting on the dose member 70 is transmitted to the blocking member 66 via the abutments 76 and 68. This force acts via the mutual axial abutment of the correspondingly shaped proximal and distal edges 27e and 67d, whereby a distally directed displacement of the blocking member 66 is prevented and impeded.

[0175] In further embodiments of the indicator member, the same interaction and positive engagement is implemented between the number sleeve and the dial sleeve, and between the dose member 70, the blocking member 66 and the inner body 20. The only exception is that the blocking member 66 is located on the dial sleeve, not on the number sleeve 161. Here, the dial sleeve and / or the number sleeve are provided with recessed apertures, like the apertures of the dial sleeve 162, which support and provide a direct mechanical interaction between the blocking member 66 and the blocking structure 26.

[0176] In this embodiment, the number sleeve and the elastic blocking member 66 may be made of different materials. Since the number sleeve is typically provided with a number or symbol on its circumference to indicate the size of the dose in the window 14 of the outer body 12, a material that is particularly suitable for printing or coating may be selected and used for the number sleeve. Different plastic materials may be selected for the blocking member 66 and for the dial sleeve integrally formed therewith, providing desired or optimized mechanical properties for the elastic deflection of the blocking member 66. For example, the dial sleeve and the blocking member 66 may be made of POM. [Explanation of symbols]

[0177] 1. Injection Device 2 Hub 3 Cover 4 Distal direction 5 Proximal 10. Housing 11 Cartridge holder 12 Outer body 13 layers 14. Windows 15 Aperture 16 threads 20 Inner body 20a shaft 21 External thread 22 Spline 23 Internal thread 24 Stop part 25a,b Stop part 26 Blocking structure 26a Distal end 26b Proximal end 27 Block screw 27a Distal end 27b Proximal end 27c Chamfered part 27d Distal Edge 27e Proximal Edge 30 Piston rod 31 External thread 32 External thread 33 Bearings 40 Drive unit 41 Thread 42 Internal thread 43 Opening 44 Finger 45 Protrusion 46 Flap 47 Stop part 50 Final Dose Nut 51 External rib 52 Internal thread 53 Stop part 60 Display material 60a Sidewall 60b Proximal part 61 Internal thread 62 Stop part 63a Stop 63b Stop part 64 teeth 65 Flexible Arm 66 Blocking member 66a Slit 66b free end 66c Base part 67 Protrusion 67d Distal Edge 68 Contact part 69 Support surface 70 Dosage components 70a Sleeve part 71 Dose Dial / Dose Button 72 Sleeve-shaped parts 73 Ribs 73a Recess 74 teeth 75 Tooth Profile 76 Contact part 80 Cartridges 81 Reservoir 82 Stopper 83 Crimped metal cap 90 Clutch 91 Spline 92 teeth 93 Aperture 94 Spline 95 teeth 100 Clicka 101 Distal Clicker 102 Proximal Clicker 103 Clutch spring 104 Spline 105 Clicker tooth 106 Click Tooth 107 Spline 108 Spline 109 teeth 110 Cartridge biasing spring 120 Cap 140 Drive unit 141 Distal Drive Sleeve 142 Proximal Drive Sleeve 143 Coupler 144 threads 145 Stop part 146 teeth 147 teeth 148 Flexible Finger 149 Hook 160 Display components 161 Number Sleeve 162 Dial Sleeve 165 Clutch Features 166 Bearing surface 167 Stop part 168 Ratchet Arm 173 Arm 174 Snap Features 220 Inner Body 227 Blocking screw 227a Recess 227b Recess 227c Recess 227d Recess Z Distal zero dose position M Proximal maximum dose position

Claims

1. 1. A drive mechanism for an injection device for setting and dispensing a dose of a medicament, said drive mechanism comprising: an inner body (20; 220) fixable within the housing (10) of the injection device (1), the inner body comprising an elongated shaft (20a) extending in an axial direction (z) and having an external thread (21); a tubular indicating member (60; 160) having an internal thread (61) which engages with the external thread (21) of the inner body (20); a dose member (70) axially displaceable relative to said indicator member (60; 160) between a dose setting position (S) and a dose dispensing position (D), the indicator member (60; 160) is movable in an axial direction (z) between a blocking position (B) and a release position (R) and comprises at least one blocking member (66) engageable with a blocking screw (27; 227) extending axially on the elongated shaft (20a) of the inner body (20; 220), the blocking screw (27; 227) and the outer thread (21; 221) having the same pitch, the at least one blocking member (66) of the indicator member (60; 160) being rotatable relative to the inner body (20; 220) between a distal zero dose position (Z) on the inner body (20; 220) and a proximal maximum dose position (M) on the inner body (20; 220) through a predetermined number of rotations, when in the blocking position (B), the blocking member (66) axially engages the dose member (70) and the blocking screw (27; 227) to prevent axial displacement of the dose member (70) from the dose setting position (S) towards the dose dispensing position (D); A drive mechanism, wherein the axial position (27a) of the distal end (27a) of the blocking screw (27, 227) on the inner body (20; 220) is offset in a proximal direction (5) from the distal zero dose position (Z) by 10% to 60% of the axial distance between the distal zero dose position (Z) and the proximal maximum dose position (M).

2. The drive mechanism of claim 1, wherein the axial position (27a) of the distal end (27a) of the blocking screw (27, 227) on the inner body (20; 220) is offset in the proximal direction (5) from the distal zero dose position (Z) by 20% to 30%, for example up to 25%, of the axial distance between the distal zero dose position (Z) and the proximal maximum dose position (M).

3. The drive mechanism of claim 1 or 2, wherein the at least one blocking member (66) of the indicator member (60; 160) is rotatable relative to the inner body (20; 220) by 1.080° to 2.160°, for example 1.440° or 1.800°, between the distal zero dose position (Z) on the inner body (20; 220) and the proximal maximum dose position (M) on the inner body (20; 220).

4. The drive mechanism of any one of claims 1 to 3, wherein the blocking screw (227) comprises at least one recess (227a, 227a, 227c, 227d) sized to accommodate the blocking member (66) and / or its radially inwardly extending projection.

5. The drive mechanism of claim 4, wherein the blocking screw (227) has at least two recesses (227a, 227a, 227c, 227d) sized to accommodate the blocking member (66) and / or its radially inwardly extending protrusion, and two adjacent recesses (227a, 227a, 227c, 227d) are spaced apart from each other by 10% to 20%, for example 12.5%, of the axial distance between the distal zero dose position (Z) and the proximal maximum dose position (M).

6. A drive mechanism according to any one of the preceding claims, wherein the blocking member (66) comprises a flexible arm extending tangentially along the circumference of the indicating member (60; 160).

7. A drive mechanism as claimed in any one of the preceding claims, wherein the blocking member (66) comprises a radially inwardly extending projection (67) on a free end section (66b) for engagement with the blocking screw (27).

8. The drive mechanism according to any one of claims 1 to 7, wherein the blocking member (66) is provided with an abutment portion (68) facing in the axial direction (z) at its free end section (66b), the abutment portion (68) axially abutting a corresponding abutment portion (76) of the dose member (70).

9. The drive mechanism according to any one of the preceding claims, wherein the axial position of the proximal end (27b) of the blocking screw (27) on the inner body (20; 220) defines a minimum size of a therapeutic dose.

10. The distal end (27a) of the blocking screw (27; 227) is chamfered, so that when the indicator (60; 160) is rotated in the dose increasing direction, the protrusion (67) of the blocking member (66) slides along the chamfer (27c) of the distal end (27a) of the blocking screw (27; 227), i) bending the free end section (66b) of said blocking member (66) in a proximal direction (5) from its release position (R) towards its blocking position (B); or A drive mechanism according to any one of claims 7 to 9, wherein ii) the locking screw (27; 227) abuts axially against a proximally facing edge (27e) of the locking screw (27; 227).

11. 11. The drive mechanism of claim 10, wherein when the indicator member (60; 160; 260) is rotated in the dose dispensing direction with the blocking member (66) in the release position (R), as the blocking member (66) enters the blocking screw (27; 227), the protrusion (67) of the blocking member (66) slides along a distal edge (27d) of the blocking screw (27; 227) as it passes a proximal end (27b) of the blocking screw (27; 227).

12. The drive mechanism according to any one of claims 1 to 11, wherein the display member comprises a number sleeve and a dial sleeve, and the at least one blocking member (66) is located on the dial sleeve or the at least one blocking member (66) is integrally formed with the dial sleeve.

13. The drive mechanism according to any one of claims 1 to 12, wherein the inner body (20) is provided on its outer periphery with at least a first maximum dose stop (25a, 25b) for engaging with first and second maximum dose stops (63a, 63b) of the indicator member (60; 160) extending radially inward when the indicator member (60) reaches a maximum dose position.

14. The device further comprises a piston rod (30) and a tubular drive part (40) extending in an axial direction (z), the piston rod (30) having a first external thread (31) which engages with an internal thread (23) of the inner body (20; 220) and an oppositely oriented second external thread (32) which engages with an internal thread (42) of the drive part (40), the dose member (70) being permanently splined to the drive part (40), the drive part (40) displacing the dose member (70) to the dose-dispensing position (D) of the inner body (20; 220).

14. The drive mechanism according to claim 1, wherein the dose member (70) and the indication member (60; 160) are selectively rotationally lockable and releaseable via a clutch (C) which rotationally engages the dose member (70) and the indication member (60; 160) when the dose member (70) is in a dose setting position (S) and which rotationally disengages the dose member (70) and the indication member (60; 160) when the dose member (70) is in a dose dispensing position (D).

15. 1. An infusion device configured to set and dispense a dose of a medication, comprising: A housing (10) for accommodating the drive mechanism according to any one of claims 1 to 14; a cartridge (80) disposed within the housing (10) and filled with a liquid medicament.

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