Method for Assembling a Drug Delivery Device

Abstract

A method of assembling a drug delivery device, the method including the steps of: providing a housing for the drug delivery device, the housing extending along a longitudinal axis between a proximal end and a distal end; providing a power unit for the drug delivery device, the power unit comprising a plunger rod and a holder that engages with the plunger rod; incorporating the power unit into the housing; providing a cap assembly extending along the longitudinal axis between the proximal end and the distal end; connecting the cap assembly to the plunger rod or the holder; and moving the cap assembly relative to the housing in a distal direction of the housing until the cap assembly is attached to a proximal end of the housing, wherein during the step of moving the cap assembly relative to the housing, the cap assembly moves the plunger rod relative to the holder.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to a method of assembling a medication delivery device, and more particularly to a method of assembling a medication delivery device that includes attaching a cap assembly to a housing. [Background technology]

[0002] Medication delivery devices, such as auto-injectors, inhalers, and on-body devices, are commonly known for allowing patients without formal medical training to self-administer medication. Therefore, these medication delivery devices typically have multiple automated functions and are provided to end users with a pre-filled medication container. The medication container typically includes a glass or plastic cylinder with a stopper seal at its rear end and a delivery member or pierceable membrane located at its front end. Due to the medication container filling process and / or the properties of the medication contained therein, some pre-filled medication containers also contain a certain amount of air. Therefore, a priming shot is required before a medication delivery operation. Furthermore, some medication containers contain substances that need to be mixed before a medication delivery operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2009 / 150078 [Patent Document 2] International Publication No. 2006 / 057604 Summary of the Invention [Problem to be solved by the invention]

[0004] It is understood that an improved solution for performing a priming shot before a drug delivery operation would be useful, and it is also understood that a new method of assembling the drug delivery device could be beneficial. [Means for solving the problem]

[0005] The invention is defined by the appended claims, to which reference should now be made.

[0006] In this disclosure, when the term "distal direction" is used, it refers to the direction away from the dose delivery site during use of the drug delivery device. When the term "distal portion / end" is used, it refers to the portion / end of the delivery device, or the portion / end of a member thereof, that is located farthest from the dose delivery site during use of the drug delivery device. Correspondingly, when the term "proximal direction" is used, it refers to the direction toward the dose delivery site during use of the drug delivery device. When the term "proximal portion / end" is used, it refers to the portion / end of the delivery device, or the portion / end of a member thereof, that is located closest to the dose delivery site during use of the drug delivery device.

[0007] Additionally, the terms "longitudinal," "longitudinally," "axially," or "axially" refer to a direction extending from the proximal end to the distal end, typically along the device and / or component in the direction of its greatest extension.

[0008] Similarly, the terms "lateral," "lateral," and "laterally" refer to directions generally perpendicular to the longitudinal direction.

[0009] Additionally, the terms "circumferential," "circumferential," or "circumferentially" refer to the circumference or direction of circumference relative to an axis, which is typically a central axis extending in the direction of the longest extension of a device and / or component. Similarly, "radial" or "radially" refers to a direction extending radially relative to that axis, and "rotational," "rotational," and "rotationally" refer to rotation relative to that axis.

[0010] Thus, there is provided a method for assembling a medication delivery device, the method comprising the steps of: providing a housing for the medication delivery device, the housing extending along a longitudinal axis between a proximal end and a distal end, the distal end of the housing pointing away from a medication delivery site during use of the medication delivery device, and the proximal end of the housing pointing towards the medication delivery site during use of the medication delivery device; providing a power unit for the medication delivery device, the power unit comprising a plunger rod and a holder engaged with the plunger rod; incorporating the power unit into the housing; providing a cap assembly extending along the longitudinal axis between the proximal end and the distal end; connecting the cap assembly to the plunger rod or the holder; and moving the cap assembly relative to the housing in a distal direction of the housing until the cap assembly is attached to the proximal end of the housing, wherein during the step of moving the cap assembly relative to the housing, the cap assembly moves the plunger rod relative to the housing when the cap assembly is connected to the plunger rod, or moves the holder relative to the housing when the cap assembly is connected to the holder.

[0011] Another aspect of the present invention provides a method for assembling a medication delivery device, the method including the steps of: providing a housing for the medication delivery device, the housing extending along a longitudinal axis between a proximal end and a distal end; providing a power unit for the medication delivery device, the power unit comprising a plunger rod and a holder that engages with the plunger rod; assembling the power unit into the housing; providing a cap assembly extending along the longitudinal axis between the proximal end and the distal end; connecting the cap assembly to the plunger rod or the holder; and moving the cap assembly relative to the housing in a distal direction of the housing until the cap assembly is attached to the proximal end of the housing, wherein during the step of moving the cap assembly relative to the housing, the cap assembly moves the plunger rod relative to the holder.

[0012] Preferably, according to another embodiment, before connecting the cap assembly to the plunger rod or holder, the method further comprises: providing a medication container; inserting a medication container into the housing from a proximal end of the housing; Further includes:

[0013] Preferably, according to another embodiment, before assembling the power unit into the housing, the method further includes the steps of providing a delivery member guard and assembling both the delivery member guard and the power unit into the housing.

[0014] Preferably according to another embodiment, the method further comprises the step of engaging the delivery member guard with the holder before or after assembling both the delivery member guard and the power unit into the housing.

[0015] Preferably, according to another embodiment, moving the plunger rod relative to the housing includes moving the plunger rod relative to the holder when the holder is stationary relative to the housing.

[0016] Alternatively, according to another embodiment, moving the plunger rod relative to the holder includes moving the plunger rod relative to the holder when the holder is stationary relative to the housing.

[0017] Preferably, according to another embodiment, the plunger rod remains stationary relative to the housing during the step of moving the holder relative to the housing.

[0018] Alternatively, according to another embodiment, moving the plunger rod relative to the holder includes moving the holder relative to the plunger rod while the plunger rod remains stationary relative to the housing.

[0019] Preferably, according to another embodiment, the step of connecting the cap assembly to the plunger rod includes contacting the proximal end of the drug container with the cap assembly from a distal end of the cap assembly.

[0020] Preferably, according to another embodiment, the step of moving the plunger rod relative to the holder includes the steps of: using the cap assembly to move the drug container distally relative to the housing; contacting the proximal end of the plunger rod with the distal end of the drug container; using the distal end of the drug container to move the plunger rod distally relative to the housing; separating the plunger rod from the holder by moving the plunger rod distally relative to the housing; and attaching the cap assembly to the proximal end of the housing.

[0021] Preferably, according to another embodiment, the step of connecting the cap assembly to the holder includes the step of moving the cap assembly proximally relative to the delivery member guard so that the cap assembly contacts the proximal end of the delivery member guard.

[0022] Preferably, according to another embodiment, the step of moving the plunger rod relative to the holder includes the steps of using the cap assembly to move the delivery member guard distally relative to the housing, using the distal movement of the delivery member guard to move the holder relative to the plunger rod, and attaching the cap assembly to the proximal end of the housing.

[0023] Preferably, according to another embodiment, moving the holder relative to the plunger rod includes rotating the holder relative to the plunger rod with distal movement of the delivery member guard.

[0024] Preferably, according to another embodiment, the step of moving the holder relative to the plunger rod includes the step of moving the holder linearly relative to the plunger rod in a direction transverse to the longitudinal axis using distal movement of the delivery member guard.

[0025] Preferably, according to another embodiment, when the cap assembly is attached to the proximal end of the housing, the cap assembly moves axially relative to the housing toward the distal end of the housing until the cap assembly snaps onto the housing.

[0026] Preferably, according to another embodiment, the medication delivery device is functionally complete after the cap assembly is attached to the proximal end of the housing.

[0027] Preferably, according to another embodiment, the drug delivery device is an injection device, an inhalation device, or a medical nebulizer.

[0028] In general, all terms used in the claims should be interpreted according to their ordinary meaning in the art, unless expressly defined otherwise herein. All references to "a / an / the" element, device, component, means, etc. should be interpreted broadly to refer to at least one instance of the element, device, component, means, etc., unless otherwise specified.

[0029] Embodiments of the inventive concept will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0030] [Figure 1A] 1 is a schematic perspective view of a drug delivery device. [Figure 1B] 1B is a schematic cross-sectional view of the rear subassembly of the drug delivery device of FIG. 1A. [Figure 2A] FIG. 1C is a schematic perspective view of the components of the rear subassembly of FIG. 1B. [Figure 2B] FIG. 1B is a schematic perspective view of components of a cap assembly of the medication delivery device of FIG. 1A. [Figure 2C] FIG. 2C is a schematic perspective view of the cap assembly of FIG. 2B without the cover. [Figure 2D] FIG. 2C is a schematic cross-sectional view of the cap assembly of FIG. 2B. [Figure 3A] 1C is a schematic cross-sectional view of the plunger rod of the rear subassembly of FIG. 1B, the plunger rod spring of the rear subassembly of FIG. 1B, and the holder of the rear subassembly of FIG. 1B. FIG. [Figure 3B] 3B is a schematic cross-sectional view of the plunger rod of FIG. 3A and the holder of FIG. 3A. [Figure 3C] 3B is a schematic perspective view of the holder of FIG. 3A and the delivery member guard of the rear subassembly of FIG. 1B. [Figure 4A] 2C is a schematic side view of the rear subassembly of FIG. 1B and the cap assembly of FIG. 2B. [Figure 4B]3B is a schematic perspective view of the holder of FIG. 3A and the delivery member guard of the rear subassembly of FIG. 1B. [Figure 4C] 3B is a schematic perspective view of the holder of FIG. 3A and the delivery member guard of the rear subassembly of FIG. 1B. [Figure 4D] 3B is a schematic cross-sectional view of the plunger rod of FIG. 3A and the holder of FIG. 3A. [Figure 5A] FIG. 1C is a schematic perspective view of the rear subassembly of FIG. 1B without the delivery member guard and drug container. [Figure 5B] FIG. 5B is a schematic cross-sectional view of a distal portion of the rear subassembly of FIG. 5A. [Figure 6A] FIG. 2C is a schematic cross-sectional view of the cap assembly of FIG. 2B. [Figure 6B] 1 is a schematic perspective view of a drug delivery device. [Figure 6C] FIG. 6C is a schematic cross-sectional view of a distal portion of the rear subassembly of FIG. 6B. DETAILED DESCRIPTION OF THE INVENTION

[0031] 1A to 6C show a medication delivery device used to describe an assembly method. The medication delivery device comprises a rear subassembly 1, a cap assembly 2, and a medication container 3. The rear subassembly 1 is a power pack of the medication delivery device. The power pack is configured to eject a medication contained in the medication container 3 of the medication delivery device when the medication delivery device is in a use state. In a preferred example, the medication delivery device is an automatic injector with an automatic function for preparing and / or mixing substances from multiple chambers in a single medication container. Alternatively, the medication delivery device can be an inhalation device or a medical nebulizer.

[0032] As shown in FIGS. 1B and 2A , the rear subassembly 1 includes a housing 10 extending along a longitudinal axis L between a proximal end and a distal end, a plunger rod 11, a plunger rod spring 12 under tension that engages the plunger rod 11, a holder 13, and a delivery member guard 14 telescopically disposed relative to the proximal end of the housing 10. As defined above, the distal end of the housing 10 points away from a drug delivery site during use of the drug delivery device, and the proximal end of the housing 10 points toward the drug delivery site during use of the drug delivery device. The rear subassembly 1 further includes a delivery member guard biasing member 15 disposed between a distally facing surface of the delivery member guard 14 and a proximally facing surface of the housing 10, and optionally, a guide rod 17 is located within the plunger rod spring 12. The housing 10 optionally includes a drug container holder 16 secured to the housing 10. The medication container holder 16 is configured to at least partially surround the medication container 3. The housing 10 further includes a fastener configured to engage with the cap assembly 2 during the assembly process. The fastener may be located on a wall of the housing, or in instances where the housing 10 includes the medication container holder 16, the fastener 16a may be located on a wall of the medication container holder 16.

[0033] The plunger rod 11, the stressed plunger rod spring 12, and the holder 13 are all disposed within the housing 10. In examples where the rear sub-assembly includes a delivery member guard biasing member 15 and a guide rod 17, both the delivery member guard biasing member 15 and the guide rod 17 are disposed within the housing 10. In examples where the housing 10 includes a medicament container holder 16, the medicament container holder 16 is also disposed within the housing 10. The stressed plunger rod spring 12 engages the plunger rod 11 at one end and engages, e.g., directly or indirectly, with the housing 10 at the other end; thus, the stressed plunger rod spring 12 is configured to drive the plunger rod 11 proximally of the housing 10 to expel the medicament contained in the medicament container 3 after the rear sub-assembly 1, the cap assembly 2, and the medicament container 3 are assembled together. When the plunger rod 11 is in a starting position relative to the holder, the holder 13 is configured to releasably hold the plunger rod 11 against a biasing force from the plunger rod spring 12. As shown in FIG. 3B, the plunger rod 11 includes a proximal retaining surface 11a that engages a distal counter retaining surface 13a of the holder 13, the distal counter retaining surface 13a being generally perpendicular to the longitudinal axis L. In one example, the plunger rod spring 12 is at least partially disposed within the plunger rod 11, as shown in FIG. 3A. In another example, the plunger rod spring surrounds at least a portion of the plunger rod. In one example, the holder 13 is a rotating body that is rotatable relative to the plunger rod 11 about the longitudinal axis L. The rotating body generally includes a tubular body and a shelf (or alternatively, a recess or notch) disposed on a surface of the tubular body to define the distal counter retaining surface 13a. In another example, the holder is a slider that is linearly movable relative to the plunger rod in a direction transverse to the housing. The holder comprises a generally tubular body and a shelf (or alternatively a recess or notch) disposed in a surface of a wall to define a distal counter-retaining surface.The holder 13 is configured to connect to a trigger of the medication delivery device and to be moved by the trigger to release the plunger rod from its original position so that the plunger rod moves proximally of the housing under the biasing force from the plunger rod spring, thus expelling the medication contained in the medication delivery device. For example, when the medication delivery device is configured to be activated by movement of the delivery member guard 14 (the delivery member guard acts as the trigger), the holder is then connected to the delivery member guard, and in another example, when the medication delivery device is configured to be activated by movement of a button such as a thumb button (the thumb button acts as the trigger), the holder is connected to the button.

[0034] The cap assembly 2 includes a cover 20 extending along a longitudinal axis L between a proximal end (closed end) and a distal end (open end). The cover 20 is configured to cover a drug delivery member, such as a needle of a drug delivery device when the drug delivery device is a syringe, before a drug delivery operation is performed, i.e., before the drug delivery device is used. Since the drug delivery member is disposed at the proximal end of the drug delivery device, the cover 20 is configured to be at least partially attached to the drug delivery device. In a preferred example, the cover is configured to cover the needle. In a preferred example, the cover 20 includes a sleeve-shaped body extending between the proximal end and the distal end. Alternatively, the cover includes a flat, button-shaped body. In this example, the drug delivery member is primarily received within the housing of the drug delivery device, and therefore the cover is configured to cover the tip of the proximal end of the drug delivery device. In one example, the cap assembly includes a delivery member shield remover disposed within the cover. In an example where the medication delivery device is an auto-injector using a medication container with a rigid needle shield and / or a flexible needle shield, the delivery member shield remover of the cap assembly is configured to fixedly engage with at least one of the rigid needle shield and the flexible needle shield of the medication container. In this example, the medication container is a syringe (a medication container with an integral needle or nozzle on the medication container). In another example, as shown in FIGS. 2B to 2D , the cap assembly 2 includes a cover and a base 23, and optionally a delivery member 21 and a delivery member holder 22. The delivery member 21, the delivery member holder 22, and the base 23 are all at least partially disposed within the cover 20 and are all movable relative to the cover 20. The delivery member 21 is fixed to the delivery member holder 22. The delivery member 21 includes a distal sharp end and a proximal delivery end. In this example, the medication container 3 is a cartridge (a medication container without an integral needle or nozzle on the medication container). The distal sharp end of the delivery member 21 is configured to pierce the proximal seal of the drug container 3 when activated to establish fluid communication between the drug container and the proximal delivery end of the delivery member 21.The proximal delivery end of the delivery member 21 is configured to deliver the contained medication to an end user. For example, the proximal delivery end of the delivery member 21 can be a needle or a spray nozzle. The base 23 includes a proximal portion 23a, a distal portion 23b, and a counter-fastener 23c. The delivery member holder 22 and the delivery member 21 are received within the proximal portion of the base 23. The counter-fastener 23c is configured to engage with the fastener 16a of the housing 10 during the assembly process of the medication delivery device. In a preferred example, the fastener 16a and the counter-fastener 23c form a snap-fit ​​engagement. In a preferred example, when the cap assembly 2 includes the delivery member 21 and the delivery member holder 22, fluid communication between the medication container and the proximal delivery end of the delivery member 21 is activated by removing the cover 20. On the other hand, in instances where the cap assembly 2 does not include a delivery member 21 and a delivery member holder 22, the end user can establish fluid communication between the drug container and the delivery member by attaching a delivery member, for example, by attaching a pen needle.

[0035] It should be noted that the present description does not describe in detail how to activate fluid communication between the medicament container and the proximal delivery end of the delivery member by removing the cover, because there are many ways to activate fluid communication between the medicament container and the proximal delivery end of the delivery member (see, for example, the disclosure of U.S. Patent No. 5,629,992), and how to activate fluid communication between the medicament container and the proximal delivery end of the delivery member is not part of the present invention. Similarly, the present description does not describe in detail how to trigger the medicament delivery operation (fully releasing the plunger rod from the holder), because there are many different ways to trigger the medicament delivery operation (see, for example, U.S. Patent No. 5,629,992), and how to trigger the medicament delivery operation is not part of the present invention.

[0036] The method of the present invention includes the steps of providing a housing 10 of a medication delivery device, providing a power unit of the medication delivery device, and assembling the power unit into the housing 10. The power unit includes a plunger rod 11 and a holder 13 engaged with the plunger rod 11. Thus, a rear subassembly 1 is assembled. The method of the present invention also includes the steps of providing a cap assembly 2 extending along a longitudinal axis L between a proximal end and a distal end, connecting the cap assembly 2 to either the plunger rod 11 or the holder 13, and moving the cap assembly 2 relative to the housing 10 in a distal direction of the housing 10 until the cap assembly 2 is attached to the proximal end of the housing 10. During the step of moving the cap assembly 2 relative to the housing 10, the cap assembly 2 moves the plunger rod 11 relative to the holder 13.

[0037] In one example, moving the plunger rod relative to the holder includes actively moving the holder 13 relative to the plunger rod 11. In this example, as shown in FIG. 3C , the holder 13 includes a guide structure 132 disposed on a wall of the holder 13. The delivery member guard 14 includes a guide follower 141 configured to move along the guide structure 132 of the holder 13. The guide follower 141 may be a protrusion extending from a surface of the delivery member guard 14 in a direction transverse to the longitudinal axis, preferably extending from a distal end face of the delivery member guard 14. In this example, the delivery member guard 14 is only movable axially relative to the housing. As the guide follower 141 moves along the guide structure 132 of the holder 13, the axial movement of the guide follower 141 is configured to rotate the holder 13 relative to the plunger rod 11 (if the holder 13 is a rotating body) or to move the holder 13 linearly relative to the plunger rod 11 in a direction transverse to the longitudinal axis L (if the holder is a slider). The guide structure 132 can be a labyrinth formed by a plurality of ledges (or alternatively, recesses or notches) on the wall of the holder 13. In the example where the holder 13 is a rotating body, the labyrinth comprises two portions 132b, 132d that extend helically in the tubular body of the rotating body; therefore, as the guide follower 141 of the delivery member guard 14 moves along the portions 132b, 132d, the rotating body will rotate relative to the plunger rod 11. On the other hand, in instances where the holder is a slider, the labyrinth comprises a diagonal portion, such that when the guide follower of the delivery member guard moves along the diagonal portion, the slider moves linearly relative to the plunger rod 11 in a direction transverse to the longitudinal axis L. It should be noted that the diagonal portion or the helically extending portion 132b, 132d can also be formed on the edge of the slider or rotor, respectively.

[0038] 4B, prior to attaching the cap assembly 2 to the proximal end of the housing 10, the guide follower 141 is positioned on the pre-assembled portion 132a of the guide structure 132. In a preferred example, the delivery member guard biasing member 15 is already assembled between the housing 10 and the delivery member guard 14. In this example, the delivery member guard 14 protrudes from the proximal end of the housing 10.

[0039] The next step is to contact the delivery member guard 14 with the cap assembly 2. In a preferred example, the distal end of the cover 20 of the cap assembly 2 is aligned with the proximal end of the housing 10, and the distal end of the cover 20 of the cap assembly 2 contacts the proximal end of the delivery member guard 14. The delivery member guard 14 is then moved distally relative to the housing 10 by the cap assembly 2. The distal movement of the delivery member guard 14 moves the guide follower 141 along one of the diagonal or spirally extending portions 132b, 132d of the guide structure 132, and thus the holder 13 rotates or moves linearly relative to the plunger rod 11 until the fastener 16a of the housing 10 engages with the counter fastener 23c of the cap assembly 2. The plunger rod 11 is now in an initial position relative to the holder 13. The delivery member guard 14 then moves to the retracted position, thereby compressing the delivery member guard biasing member 15. The guide follower 141 is thereby located at the intermediate position 132c of the guide structure 132 of the holder 13. Therefore, when the end user wants to use the medication delivery device, the end user will first remove the cover 20 from the medication delivery device. Once the cover 20 is removed, the delivery member guard 14 will move proximally relative to the housing 10 under the biasing force of the delivery member guard biasing member 15. The guide follower 141 thereby moves along the diagonal portion or the other of the spirally extending portions 132b, 132d of the guide structure 132, and thus the plunger rod 11 is released from the initial position and moves to the start position. The initial operation of the medication delivery device is thereby performed. When the plunger rod 11 is in the starting position, the plunger rod 11 can engage with the holder 13, or any other suitable component, to hold the plunger rod against the force of the plunger rod spring prior to the drug delivery operation. In a preferred example, the holder 13 includes a second distal counter-retaining surface 13b, as shown in FIG. 4D.The second distal counter retaining surface 13b extends circumferentially from one end of the distal counter retaining surface 13a relative to the longitudinal axis L and is angled, e.g., between 10 and 80 degrees, relative to the distal counter retaining surface 13a. In this example, the guide follower 141 is configured to prevent rotation or linear, transverse movement of the holder 13 (depending on whether the holder 13 is a rotor or a slider) when the guide follower 141 is located in the intermediate position 132c of the guide structure 132. For example, the guide structure 132 can include one or more ledges that abut the guide follower 141 in a direction transverse to the longitudinal axis L. In this example, the proximal retaining surface 11a engages the distal counter retaining surface 13a when the plunger rod 11 is in its home position. During the assembly step of moving the holder 13 relative to the plunger rod 11, the plunger rod 11 moves to an initial position so that the proximal retaining surface 11 a engages with the second distal counter retaining surface 13 b. In this example, the second distal counter retaining surface 13 b is an inclined surface, so that when the guide follower 141 moves away from the intermediate position 132 c of the guide structure 132, the holder 13 will be moved by the plunger rod 11 under the force of the plunger rod spring 12. Therefore, the delivery member guard biasing member 15 does not need to be strong, and the holder may only have one diagonal or spiral extending portion, depending on the selection of the angle of the second distal counter retaining surface, because in this case the holder can be moved by the engagement between the second distal counter retaining surface and the plunger rod. In this example, the drug container 3 may be a cartridge or a syringe, and the drug container 3 may be incorporated into the housing of the rear subassembly from the proximal end of the housing 10 or from the distal end of the housing. In a preferred example, before attaching the cap assembly 2 to the proximal end of the housing 10, the method further includes the steps of providing the drug container 3 and inserting the drug container 3 into the housing 10 from the proximal end of the housing.Therefore, the step of attaching the cap assembly 2 is the final step in assembling the drug delivery device, which from a functional point of view means that the drug delivery device is ready for use by the end user (from a legal / commercial point of view, the drug delivery device may further need to be labeled and / or packaged).

[0040] In another example, moving the plunger rod 11 relative to the holder 13 includes actively moving the plunger rod 11 relative to the holder 13. This example is suitable for assembling a drug delivery device including a cartridge, and with this assembly step, before attaching the cap assembly 2 to the proximal end of the housing 10, the method further includes providing a drug container 3 and inserting the drug container 3 into the housing 10 from the proximal end of the housing, as shown in FIG. 5A. In this example, when the rear subassembly 1 is provided, the plunger rod 11 is in its original position, meaning that the proximal retaining surface 11 a engages with the distal counter retaining surface 13 a of the holder 13, as shown in FIG. 5B. During assembly, the distal end of the cover 20 of the cap assembly 2 is aligned with the proximal end of the housing 10. 6A , the step of moving the plunger rod 11 relative to the holder 13 includes a step of contacting the proximal end of the drug container 3 with the distal portion 23b of the base 23, thereby contacting the proximal shoulder portion with the distal portion 23b of the base 23. Therefore, the step of attaching the cap assembly 2 to the proximal end of the housing can also push the plunger rod 11 distally relative to the holder 13 against the force of the plunger rod spring 12. The steps further include moving the medicament container 3 distally relative to the housing 10 using the cap assembly 2, bringing the proximal end of the plunger rod 11 into contact with the distal end of the medicament container 3 as shown in Figure 6B, moving the plunger rod 11 distally relative to the housing 10 using the distal end of the medicament container 3, and moving the proximal holding surface 11a of the plunger rod 11 away from the distal counter-holding surface 13a of the holder 13 in the direction of the longitudinal axis L as shown in Figure 6C. The cartridge is a sealed medicament container such that the contained medicament cannot be expelled from the medicament container before fluid communication is established between the medicament container and the delivery member.Thus, when the cap assembly 2 is attached to the proximal end of the housing 10, the distal portion 23b of the base 23 pushes the drug container to move the plunger rod 11 distally relative to the holder 13 to its initial position, and the plunger rod 11 is subsequently prevented by the drug container from moving back to its original / starting position. When the end user establishes fluid communication between the drug container and the delivery member 21 by removing the cover 20 or by attaching a delivery member such as a pen needle, the drug container is no longer sealed and cannot prevent the plunger rod 11 against the force of the plunger rod spring 12, and therefore the plunger rod 11 moves proximally relative to the holder 13 until the proximal surface 11a of the plunger rod 11 engages the distal counter-retaining surface 13a of the holder 13, thus performing the initial actuation of the drug delivery device. In this example, the delivery member guard 14 is moved to a retracted position by the cap assembly 2, or is simply enclosed by the cover of the cap assembly 2.

[0041] The inventive concept has been described above primarily with reference to a few examples, however, as will be readily apparent to those skilled in the art, other embodiments than those described above are equally possible within the scope of the inventive concept as defined in the appended claims. [Explanation of symbols]

[0042] 1 Rear subassembly 2 Cap assembly 3. Medicine containers 10. Housing 11 Plunger rod 11a Proximal holding surface 12 Stressed plunger rod spring 13 Holder 13a Distal counter-holding surface 13b second distal counter-retaining surface 14 Delivery member guard 15 Delivery member guard biasing member 16 Drug container holder 16a Fasteners 17 Guide rod 20 Cover 21 Delivery member 22 Delivery member holder 23 Base 23a proximal part 23b Distal part 23c Counter fastener 132 Guide structure 132a Pre-assembled part 132b part 132c intermediate position 132d part 141 Guide Follower L longitudinal axis

Claims

1. 1. A method of assembling a medication delivery device, comprising: providing a housing (10) for the medication delivery device, the housing (10) extending along a longitudinal axis (L) between a proximal end and a distal end, the distal end of the housing (10) pointing away from a medication delivery site during use of the medication delivery device, and the proximal end of the housing (10) pointing towards the medication delivery site during use of the medication delivery device; providing a power unit of the medication delivery device, the power unit comprising a plunger rod (11) and a holder (13) engaging with the plunger rod; Assembling the power unit into the housing (10); providing a cap assembly (2) extending along the longitudinal axis (L) between a proximal end and a distal end, the cap assembly (2) comprising a cover (20) configured to cover a medication delivery member of the medication delivery device; connecting the cap assembly (2) to the plunger rod (11) or the holder (13); moving the cap assembly (2) relative to the housing (10) in a distal direction of the housing (10) until the cap assembly (2) is attached to the proximal end of the housing (10); Including, During the step of moving the cap assembly (2) relative to the housing (10), the cap assembly (2) (i) moving the plunger rod (11) relative to the housing (10) when the cap assembly (2) is connected to the plunger rod (11); or (ii) moving the holder (13) relative to the housing (10) when the cap assembly is connected to the holder (13); method.

2. Prior to the step of connecting the cap assembly (2) to the plunger rod (11) or the holder (13), the method comprises: providing a medication container; inserting the medication container into the housing from the proximal end of the housing; The method of claim 1 further comprising:

3. Before the step of assembling the power unit into the housing (10), the method comprises: providing a delivery member guard (14); Assembling the delivery member guard (14) and the power unit together in the housing (10); 3. The method of claim 1 or 2, further comprising:

4. The method comprises: Engaging the delivery member guard (14) with the holder before or after assembling both the delivery member guard (14) and the power unit into the housing (10). The method of claim 3 further comprising:

5. 5. The method of claim 1, wherein moving the plunger rod relative to the housing comprises moving the plunger rod relative to the holder while the holder is stationary relative to the housing.

6. The method of claim 1 , wherein the plunger rod remains stationary relative to the housing during the step of moving the holder relative to the housing.

7. The step of connecting the cap assembly (2) to the plunger rod (11) comprises: contacting the proximal end of the medication container with the cap assembly from the distal end of the cap assembly.

6. The method of any one of claims 3 to 5 when relying on claim 2, comprising:

8. The step of moving the plunger rod (11) relative to the holder (13) includes: moving the medicament container in the distal direction relative to the housing with the cap assembly; contacting a proximal end of the plunger rod with a distal end of the medication container; using the distal end of the medicament container to move the plunger rod in the distal direction relative to the housing; moving the plunger rod in the distal direction relative to the housing to separate the plunger rod from the holder; attaching the cap assembly (2) to the proximal end of the housing (10); The method of claim 7, comprising:

9. The method of claim 6 when claim 4 is reliant on claim 4, wherein the step of connecting the cap assembly (2) to the holder includes the step of moving the cap assembly in a proximal direction relative to the delivery member guard so that the cap assembly contacts the proximal end of the delivery member guard.

10. 10. The method of claim 9, wherein the step of moving the plunger rod (11) relative to the holder (13) includes the steps of: using the cap assembly to move the delivery member guard in the distal direction relative to the housing; using the distal movement of the delivery member guard to move the holder relative to the plunger rod; and attaching the cap assembly (2) to the proximal end of the housing (10).

11. The method of claim 10 , wherein moving the holder relative to the plunger rod comprises rotating the holder relative to the plunger rod with the distal movement of the delivery member guard.

12. 11. The method of claim 10, wherein moving the holder relative to the plunger rod includes using the distal movement of the delivery member guard to move the holder linearly relative to the plunger rod in a direction transverse to the longitudinal axis.

13. 13. The method of claim 1, wherein when the cap assembly is attached to the proximal end of the housing, the cap assembly is moved axially relative to the housing toward the distal end of the housing until the cap assembly snaps onto the housing.

14. 14. The method of any one of claims 2 to 13, wherein the medication delivery device is functionally complete after the cap assembly is attached to the proximal end of the housing.

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