Drug Delivery Device and Assembly Method for a Drug Delivery Device

Abstract

The present invention refers to a drug delivery device comprising a housing (5, 10) with an opening (12), a piston rod (11) having a proximal end and a distal end, at least a portion with an interface (14) adapted to engage the opening (12) for guiding the piston rod (11) during a distal or proximal movement of the piston rod (11) relative to the housing (5, 10) and at least one first attachment element (15) located at the distal end, and a bearing (16) with at least one second attachment element (17, 18) for rotatable attachment of the bearing (16) at the distal end of the piston rod (11). The at least one first attachment element (15) and/or the at least one second attachment element (17, 18) is elastically deformable in a radial direction for snap engagement of the piston rod (11) and the bearing (5, 10). The opening (12) comprises at least one portion having a contour adapted to receive the at least one first attachment element (15) and the at least one second attachment element (17, 18) if attached to each other but preventing disengagement of the at least one first attachment element (15) and the at least one second attachment element (17, 18) if received in the opening (12). Further, the present invention refers to an assembly method for a drug delivery device.

Claims

1. A drug delivery device comprising a housing (5, 10) with an opening (12), a piston rod (11) having a proximal end and a distal end, at least a portion with an interface (14) adapted to engage the opening (12) for guiding the piston rod (11) during a distal or proximal movement of the piston rod (11) relative to the housing (5, 10) and at least one first attachment element (15) located at the distal end, and a bearing (16) with at least one second attachment element (17, 18) for rotatable attachment of the bearing (16) at the distal end of the piston rod (11), wherein the at least one first attachment element (15) and/or the at least one second attachment element (17, 18) is elastically deformable in a radial direction for snap engagement of the piston rod (11) and the bearing (5, 10), wherein the opening (12) comprises at least one portion having a contour adapted to receive the at least one first attachment element (15) and the at least one second attachment element (17, 18) if attached to each other but preventing disengagement of the at least one first attachment element (15) and the at least one second attachment element (17, 18) if received in the opening (12).

2. The drug delivery device according to claim 1, wherein, during assembly of the drug delivery device, the piston rod (11) is axially movable between a distal mounting position in which the at least one first attachment element (15) and the at least one second attachment element (17, 18) are located distally from the opening (12) and a proximal transport position in which the at least one first attachment element (15) and the at least one second attachment element (17, 18) are received in the opening (12).

3. The drug delivery device according to claim 1 or 2, wherein the opening is provided with an internal thread and wherein the interface (14) adapted to engage the opening (12) for guiding the piston rod (11) during a distal or proximal movement of the piston rod (11) relative to the housing (5, 10) comprises an external thread (14).

4. The drug delivery device according to claim 3, wherein the at least one portion having a contour adapted to receive the at least one first attachment element (15) and the at least one second attachment element (17, 18) comprises the internal thread (13).

5. The drug delivery device according to claim 1 or 2, wherein the opening is provided with a non-circular cross-section and wherein the interface adapted to engage the opening (12) for guiding the piston rod (11) during a distal or proximal movement of the piston rod (11) relative to the housing (5, 10) comprises a corresponding non-circular cross-section.

6. The drug delivery device according to claim 5, wherein the at least one portion having a contour adapted to receive the at least one first attachment element (15) and the at least one second attachment element (17, 18) comprises a protrusion.

7. The drug delivery device according to any one of the preceding claims, wherein the bearing (16) comprises a disc for abutting a bung of a cartridge and wherein the at least one second attachment element (17, 18) comprises a spigot (17) extending proximally from the proximal side of the disc, wherein the spigot (17) comprises at least one radial recess (18).

8. The drug delivery device according to claim 7, wherein the at least one first attachment element (15) of the piston rod (11) comprises at least one snap hook (15) adapted to engage the at least one radial recess (18) of the bearing (16).

9. The drug delivery device according to any one of claims 1 to 6, wherein the at least one first attachment element of the piston rod (11) comprises a spigot at its distal end, wherein the spigot comprises at least one radial recess.

10. The drug delivery device according to claim 9, wherein the bearing (16) comprises a disc for abutting a bung of a cartridge and the at least one second attachment element comprises at least one snap hook extending proximally from the proximal side of the disc and adapted to engage the at least one radial recess of the piston rod (11).

11. The drug delivery device according to any one of the preceding claims, further comprising a drive member (20) operatively coupled to the piston rod (11) for displacing the piston rod (11) in the distal direction and/or a dose setting member (6, 8, 22) operatively coupled to the housing (5, 10) for selecting a dose and/or a cartridge holder (9) attached to the housing (5, 10) and containing a cartridge containing a medicament.

12. The drug delivery device according to any one of the preceding claims, wherein the opening (12) comprises at least one portion having a contour adapted to receive the at least one first attachment element (15) and the at least one second attachment element (17, 18) with a clearance fit or an interference fit permitting axial movement of the bearing (16) and the piston rod (11) if attached to each other but blocking elastic deformation of at least one of the attachment elements (15) required for disengagement of the at least one first attachment element (15) and the at least one second attachment element (17, 18) if received in the opening (12).

13. An assembly method for a drug delivery device, the device comprising at least a housing (5, 10) with an opening (12), a piston rod (11) having a proximal end and a distal end and at least one first attachment element (15) located at the distal end, and a bearing (16) with at least one second attachment element (17, 18) for rotatable attachment of the bearing (16) at the distal end of the piston rod (11), the method comprising the steps of: introducing the piston rod (11) into the housing (5, 10) such that the distal end of the piston rod (11) distally protrudes through the opening (12), thereafter attaching the bearing (16) on the piston rod (11) by snap engagement of the at least one first attachment element (15) and the at least one second attachment element (17, 18), thereafter retracting the piston rod (11) in the proximal direction until the at least one first attachment element (15) and the at least one second attachment element (17, 18) are at least partially received in the opening (12) of the housing (5, 10).

14. The assembly method according to claim 13, wherein the steps of introducing the piston rod (11) in the distal direction into the housing (5, 10) and/or retracting the piston rod (11) in the proximal direction involves a combined rotation and translation of the piston rod (11).

15. The assembly method according to claims 13 or 14, wherein the step of attaching the bearing (16) on the piston rod (11) involves elastically deforming the at least one first attachment element (15) and/or the at least one second attachment element (16, 17) in a radial direction.

16. The assembly method according to any one of claims 13 to 15, further comprising the step of attaching a cartridge holder (9) containing a cartridge containing a medicament to the housing (5, 10) such that the bearing (16) abuts a bung in the cartridge.

Description

[0050] Non-limiting, exemplary embodiments of the invention will now be described with reference to the accompanying drawings, in which:

[0051] FIG. 1 shows a drug delivery device with a dose setting mechanism in accordance with one aspect of the present invention;

[0052] FIG. 2 shows the drug delivery device of FIG. 1 with a cap removed and showing a cartridge holder;

[0053] FIG. 3 shows a sectional view of an embodiment of the drug delivery device according to the invention prior to assembly of a bearing; and

[0054] FIG. 4 shows a sectional view of the embodiment of FIG. 1 after assembly of the bearing.

[0055] Referring to FIG. 1, there is shown a drug delivery device 1 in accordance with an exemplary arrangement. The drug delivery device 1 comprises a distally arranged cartridge retaining part 2 and a proximally arranged dose setting mechanism 3. The drug delivery device may be a resettable drug delivery device (i.e., a reusable device) or alternatively a non-resettable drug delivery device (i.e., a non-reusable device). The cartridge retaining part 2 and the dose setting mechanism 3 are secured together by connecting features. For non-resettable devices, these connecting features would be permanent and non-reversible. For resettable devices, these connecting features would be releasable.

[0056] In this illustrated arrangement, the cartridge retaining part 2 is secured within the dose setting mechanism 3. A removable cap 4 is releasably retained over the cartridge retaining part 2. The dose setting mechanism 3 is encased by an outer housing 5 and comprises a dose dial grip 6 and a window or lens 7. A dose scale arrangement 8 is viewable through the window or lens 7.

[0057] To set a dose of medication contained within the drug delivery device 1, a user rotates the dose dial grip 6 relative to the outer housing 5 such that a dialed dose will become viewable in the window or lens 7 by way of the dose scale arrangement 8. Dose setting may involve a proximal movement of the dose dial grip 6 with respect to the outer housing 5 as shown in FIG. 2. Dose dispensing may involve pushing the dose dial grip back in the distal direction.

[0058] FIG. 2 illustrates the drug delivery device 1 of FIG. 1 with the cover cap 4 removed from a distal end of the device 1. This removal exposes a cartridge holder 9. A cartridge (not shown) from which a number of doses of a medicinal product may be dispensed, is provided in the cartridge holder 9. The cartridge comprises a bung or stopper (not illustrated in FIG. 2) that is retained near a proximal end of the cartridge.

[0059] The drug delivery device, in particular the dose setting mechanism 3, may also comprise an inner housing 10 or insert which may be a separate component part as depicted in FIG. 3 or may be an integral component part of the outer housing 5. The drug delivery device further comprises a piston rod 11 or a spindle having a distal end facing towards the cartridge retaining part 2 and an opposite proximal end.

[0060] In the embodiment depicted in FIG. 3, the inner housing 10 is provided with a central opening 12 receiving of the piston rod 11. As an alternative to the depicted embodiment, the opening 12 may be provided directly in the outer housing 5. The opening 12 is provided with an inner thread 13 interacting with an outer thread 14 of the piston rod 11. Thus, rotation of the piston rod 11 with respect to the inner housing 10 results in an axial displacement of the piston rod 11 with respect to the inner housing 10. The distal end of the piston rod 11 is provided with a female snap feature, for example comprising two flexible hooks 15. The hooks 15 are designed such that they can be elastically deformed in a radial direction, thereby widening the female snap feature.

[0061] The dimensions of the central opening 12 with its inner thread 13 and to the flexible hooks 15 are chosen such that the central opening 12 and the inner thread 13 do not interfere with the flexible hooks 15 in the unstressed (at rest) condition of the hooks as depicted in FIGS. 3 and 4. However, the central opening 12 with its inner thread 13 substantially prevents widening of the flexible hooks 15 in the radial direction. The at least one flexible hook 15 constitutes a first attachment element.

[0062] The drug delivery device further comprises a bearing 16 which is depicted in FIG. 3 prior to attachment on the piston rod 11. The bearing 16 is substantially disc-shaped and comprises a spigot 17 or stem extending in the proximal direction. The spigot 17 is provided with an annular recess 18 or groove arranged between the proximal end of the spigot 17 and the disc-shaped portion of the bearing 16. The spigot 17 with its recess 18 constitutes a second attachment element. The dimensions of the spigot 17 and the recess 18 are adapted to the dimensions of the female snap features, i.e. the flexible hooks 15, of the piston rod 11 such that the bearing 16 can be attached to the distal end of the piston rod 11 by a snap engagement of the spigot 17 into the flexible hooks 15.

[0063] As an alternative to the embodiments depicted in FIGS. 3 and 4 the spigot with the recess may be provided on the piston rod 11 and the female snap features may be provided on the bearing 16.

[0064] FIGS. 3 and 4 illustrate two steps during assembly of the drug delivery device 1, especially attachment of the bearing 16 on the piston rod 11. FIG. 3 shows the piston rod 11 advanced through the thread 13 of the inner housing 10 into a distal mounting position and ready to clip to the bearing 16. To clip the piston rod 11 into the bearing 16, either the bearing can be pushed to the right (as seen in FIG. 3), or the piston rod 11 can be advanced by rotating it though the threaded aperture in the inner housing 10 by an amount equal to that required to fully assemble the snap connection.

[0065] In FIG. 4, the piston rod 11 has been clipped into the bearing and then the piston rod 11 rotated backwards so that it moves to the right (as seen in FIG. 4) axially and pulls the bearing 16 back into the region of the thread form 13 of the inner housing 10. This retraction of the piston rod 11 serves to lock the snaps (hooks 15) from deflection radially outwards and therefore prevents the bearing 16 from becoming detached without considerable force being applied.

[0066] In the example depicted in the Figures, the inner housing 10 is provided with a substantially cylindrical coupling portion 19 extending in the distal direction with respect to the opening 12. The coupling portion 19 may be adapted for rigidly constraining the inner housing 10 to the outer housing 5.

[0067] In the exemplary embodiment of FIGS. 3 and 4 the drug delivery device further comprises driver 20 interacting with the piston rod 11, e.g. by means of a splined engagement. The driver 20 may be provided with an external thread engaging a nut 21 which may limit the maximum amount of drug which may be dispensed from the drug delivery device 1. FIGS. 3 and 4 further show a portion of the dose setting sleeve 22 which may be an integral portion of the dose dial grip 6 and/or the dose scale arrangement 8. As an alternative, the dose setting sleeve 22 may be coupled to the dose dial grip 6 and/or the dose scale arrangement 8 and or the driver 20.

[0068] For example, dose setting may involve rotation of the dose setting sleeve 22 in a first direction via the dose dial grip 6. This rotation may be a rotation relative to the outer housing 5 and the inner housing 10 and/or a rotation relative to the driver 20.

[0069] Dose dispensing may involve rotating the dose setting sleeve 22 in a second direction which is opposite to the first direction. During dose dispensing the driver 20 may be rotationally coupled to the dose setting sleeve 22. Rotation of the driver 20 may be transferred to the piston rod 11 which due to the threaded engagement with the inner housing 10 moves in the distal direction upon rotation. This distal movement of the piston rod 11 with the bearing 16 may push the bung in the cartridge in the distal direction for dispensing a dose of the medicament.

[0070] As an alternative, rotating the dose setting sleeve 22 during dose dispensing may involve an axial or helical movement of the driver 20 which may be transferred via a threaded interface to the piston rod 11. This may result in a pure axial or a combined axial and rotational movement of the piston rod 11 with the bearing 16 to push the bung in the cartridge in the distal direction for dispensing a dose of the medicament.

REFERENCE NUMERALS

[0071] 1 drug delivery device [0072] 2 cartridge holder [0073] 3 housing [0074] 4 dose setting mechanism [0075] 5 cap [0076] 6 dose dial grip [0077] 7 window/lens [0078] 8 dose scale arrangement [0079] 9 cartridge holder [0080] 10 inner housing [0081] 11 piston rod [0082] 12 opening [0083] 13 inner thread [0084] 14 outer thread [0085] 15 hook/female snap feature (first attachment element) [0086] 16 bearing [0087] 17 spigot (second attachment element) [0088] 18 recess [0089] 19 coupling portion [0090] 20 driver [0091] 21 nut [0092] 22 dose setting sleeve