Drive mechanism for a drug delivery device and drug delivery device

Abstract

The present invention concerns a drive mechanism for a drug delivery device comprising a housing having a longitudinal axis, a first feedback element which is movable along the longitudinal axis relative to the housing and a second feedback element, wherein the first feedback element and the second feedback element are adapted to interact with each other thereby providing at least one of tactile and audible feedback during at least one of a dose setting and dose dispensing operation of the drive mechanism. Moreover a drug delivery device incorporating such a drive mechanism is disclosed.

Claims

1. A drive mechanism for a drug delivery device, comprising: a housing having a longitudinal axis, a first feedback element which is movable along the longitudinal axis relative to the housing, the first feedback element comprising a helical structure, and a second feedback element, wherein the first feedback element and the second feedback element are adapted to interact with each other, thereby providing at least one of tactile and audible feedback during a dose setting operation of the drive mechanism, wherein the first feedback element comprises a first surface configured to interact with the second feedback element during a dose setting operation of the drive mechanism, wherein the first surface comprises first protrusions, the first feedback element comprises a second surface comprising second protrusions, wherein the first and second protrusions are arranged opposite one another to result in an audible or tactile feedback when interacting with the second feedback element, and wherein the second protrusions are configured to interact with the second feedback element during at least one of the dose setting and a dose dispensing operation of the drive mechanism.

2. The drive mechanism according to claim 1, wherein the first feedback element and the second feedback element are configured to provide feedback during at least one of a dose setting and dose dispensing operation of the drive mechanism.

3. The drive mechanism according to claim 1, comprising a dose member which comprises the first feedback element.

4. The drive mechanism according to claim 1, wherein the first surface comprises the first protrusions at its proximal end and the second surface comprises the second protrusions at its distal end.

5. The drive mechanism according to claim 1, wherein the first feedback element comprises a groove.

6. The drive mechanism according to claim 1, wherein the first protrusions are equally spaced along the first surface.

7. The drive mechanism according to claim 1, wherein the first protrusions are spaced further apart at one end of the first surface than at another end of the first surface.

8. The drive mechanism according to claim 1, wherein the second surface is configured to interact with the second feedback element during at least one of a dose setting and dose dispensing operation of the drive mechanism.

9. The drive mechanism according to claim 1, comprising a sleeve, wherein the first feedback element is arranged at a surface of the sleeve.

10. The drive mechanism according to claim 1, wherein the second feedback element comprises a peg.

11. The drive mechanism according to claim 1, wherein the second feedback element is rotatable around the longitudinal axis of the housing.

12. The drive mechanism according to claim 1, wherein the second feedback element is prevented from moving along the longitudinal axis of the housing.

13. A drug delivery device comprising the drive mechanism according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Further features, refinements and expediencies become apparent from the following description of the exemplary embodiments in connection with the figures.

(2) FIG. 1 schematically shows a partly sectional side view of an exemplary embodiment of a drug delivery device.

(3) FIG. 2 schematically shows a perspective partly sectional view of a part of a drive mechanism according to a first embodiment.

(4) FIG. 3 schematically shows a perspective view of a dose member.

(5) FIG. 4 schematically shows a perspective view of a dose member being part of a drive mechanism according to a first embodiment.

(6) FIG. 5 shows a more detailed perspective view of a part of FIG. 4.

(7) FIG. 6 schematically shows a perspective view of a drive mechanism according to a second embodiment.

(8) FIG. 7 schematically shows a perspective view of a part of FIG. 6.

(9) FIG. 8 illustrates a more detailed perspective view of a part of FIG. 4 with alternative helical grooves where both side walls have structured surfaces.

(10) Like elements, elements of the same kind and identically acting elements may be provided with the same reference numerals in the figures.

DETAILED DESCRIPTION

(11) Turning now to FIG. 1, a drug delivery device 1 comprises a cartridge unit 2 and a drive mechanism 3. The cartridge unit 2 comprises a cartridge 4. Medication 5 is retained in the cartridge 4. The medication 5 is preferably liquid medication. The cartridge 4 preferably comprises a plurality of doses of the medication 5. The medication 5 may comprise insulin, heparin, or growth hormones, for example. The cartridge 4 has an outlet 6 at its distal end 28. Medication 5 can be dispensed from the cartridge through outlet 6. The device 1 may be a pen-type device, in particular a pen-type injector. The device 1 may be a disposable or a reusable device. The device 1 may be a device configured to dispense fixed doses of the medication or variable, preferably user-settable, doses. The device 1 may be a needle-based or a needle free device. The device 1 may be an injection device.

(12) The term distal end of the medication delivery device 1 or a component thereof may refer to that end of the device or the component which is closest to the dispensing end of the device 1. The term proximal end of the medication delivery device 1 or a component thereof may refer to that end of the device or the component which is furthest away from the dispensing end of the device. In FIG. 1, the distal end of the device 1 is assigned reference numeral 7 and the proximal end of the device is assigned reference numeral 8.

(13) The outlet 6 may be covered by a membrane 9, which protects medication 5 against external influences during storage of the cartridge. For medication delivery, membrane 9 may be opened, e.g. pierced. For example, membrane 9 may be pierced by a needle unit (not explicitly shown). The needle unit may be (releasably) attached to the distal end 7 of the cartridge unit 2. The needle unit may provide for fluid communication from the inside of the cartridge 4 to the outside of the cartridge through outlet 6.

(14) A piston 10 is retained within the cartridge 4. The piston 10 is movable with respect to the cartridge 4. The piston 10 may seal the medication 5 within the cartridge 4. The piston 10 expediently seals the interior of the cartridge 4 proximally. Movement of the piston 10 with respect to the cartridge 4 in the distal direction causes medication 5 to be dispensed from the cartridge through outlet 6 during operation of the device.

(15) The cartridge unit 2 furthermore comprises a cartridge retaining member 11. The cartridge 4 is retained within the cartridge retaining member 11. The cartridge retaining member 11 may stabilize the cartridge 4 mechanically. Additionally or alternatively, the cartridge retaining member 11 may be provided with a fixing member (not explicitly shown) for attaching the cartridge unit 2 to the drive mechanism 3.

(16) The cartridge unit 2 and the drive mechanism 3 are secured to one another, preferably releasably secured.

(17) The drive mechanism 3 is configured for transferring force, preferably user-exerted force, particularly preferably manually exerted force, to the piston 10 for displacing the piston 10 with respect to the cartridge 4 in the distal direction. A dose of medication 5 may be dispensed from the cartridge 4 in this way. The size of the delivered dose may be determined by the distance by which the piston 10 is displaced with respect to the cartridge 4 in the distal direction.

(18) The drive mechanism 3 comprises a piston rod 12. The piston rod 12 may be configured for transferring force to the piston 10, thereby displacing the piston in the distal direction with respect to the cartridge 4. A distal end face of the piston rod 12 may be arranged to abut a proximal end face of the piston 10. A bearing member (not explicitly shown) may be arranged to advance the piston 10, preferably to abut the proximal end face of the piston 10.

(19) The drive mechanism 3 comprises a housing 13. The piston rod 12 may be retained in the housing. A proximal end side 14 of the cartridge unit 2 may be secured to the drive mechanism 3 at a distal end side 15 of the housing 13, for example via a threaded connection. Housing 13, cartridge 4 and/or cartridge retaining member 11 may have a tubular shape.

(20) The term housing shall preferably mean any exterior housing (main housing, body, shell) or interior housing (insert, inner body) which may have a unidirectional axial coupling to prevent proximal movement of specific components. The housing may be designed to enable the safe, correct, and comfortable handling of the medication delivery device or any of its mechanism. Usually, it is designed to house, fix, protect, guide, and/or engage with any of the inner components of the medication delivery device (e.g., the drive mechanism, cartridge, piston, piston rod), preferably by limiting the exposure to contaminants, such as liquid, dust, dirt etc. In general, the housing may be unitary or a multipart component of tubular or non-tubular shape.

(21) The term piston rod shall preferably mean a component adapted to operate through/within the housing, which may be designed to transfer axial movement through/within the drug delivery device, preferably from a drive member to the piston, for example for the purpose of discharging/dispensing an injectable product. Said piston rod may be flexible or not. It may be a simple rod, a lead-screw, a rack and pinion system, a worm gear system, or the like. Piston rod shall further mean a component having a circular or non-circular cross-section. It may be made of any suitable material known by a person skilled in the art and may be of unitary or multipart construction.

(22) The drive mechanism 3 comprises a dose button 37. The dose button 37 is movable with respect to the housing 13. The dose button 37 may be movable in the proximal direction with respect to the housing for setting of a dose of the medication 5 which is to be delivered and in the distal direction with respect to the housing for delivery of the set dose. The dose button 37 is preferably connected to the housing 13. The dose button 37 may be secured against rotational movement with respect to the housing. The dose button 37 may be moved (displaced) between a proximal end position and a distal end position with respect to the housing 13 (not explicitly shown).

(23) The device 1 may be a manually, in particular non-electrically, driven device. The (user-applied) force which causes the dose button 37 to be moved with respect to the housing 13 in the distal direction may be transferred to the piston rod 12 by a drive member. For this purpose, other elements of the drive mechanism may be provided which are not explicitly shown in FIG. 1. The drive mechanism is preferably configured to not move the piston rod 12 with respect to the housing 13 when the dose button 37 is moved in the proximal direction with respect to the housing 13 for setting of the dose.

(24) Embodiments of a drive mechanism which are suitable to be provided in the drug delivery device 1 as it was described above are described in more detail below.

(25) A first embodiment of a drive mechanism which is suitable for being implemented in the medication delivery device 1 as described above is described in connection with FIGS. 2 to 7.

(26) FIG. 2 schematically shows a perspective sectional view of a part of a drive mechanism.

(27) The drive mechanism 3 comprises a dose member 16 comprising a dose element 17 and a dose sleeve 18. The dose sleeve 18 is fixed to the dose element 17. Accordingly, the dose sleeve 18 can not move axially or rotationally relative to the dose element 17. The dose element 17 is arranged inside the housing 13. The dose element 17 may be coupled to the dose button (not shown) which may extend out of the housing 13.

(28) The dose member 16 is movable with respect to the housing 13. The dose member 16 may be movable in the proximal direction with respect to the housing for setting a dose of the medication 5 which is to be delivered and in the distal direction with respect to the housing for delivery of the set dose. The dose member 16 is preferably engaged with the housing 13. The dose member 16 may be secured against rotational movement with respect to the housing. The dose member 16 may be moved (displaced) between a proximal end position and a distal end position with respect to the housing 13 (not explicitly shown). The distance by which the dose member 16 is displaced with respect to the housing 13 during setting of the dose may correspond to a size of the dose. The proximal end position and the distal end position may be determined by a respective stop feature which may limit the proximal or distal travel of the dose member with respect to the housing. In one embodiment, the stop feature limiting the proximal or distal travel of the dose member may be the second feedback element. In particular, the stop feature may be shaped as a ring comprising a protrusion.

(29) To set a dose, a user may manually move dose member 16 in the proximal direction with respect to the housing 13. To do so, the user may grip the dose button and pull it in the proximal direction. Thereby, the dose element 17 and accordingly the dose member 16 move proximally also with respect to the drive member.

(30) After the dose has been set, the dose button is moved (pushed) by the user in the distal direction with respect to housing 13. Thus, the dose member 16 is moved in the distal direction with respect to the housing 13.

(31) The dose element 17 may comprise a guide feature, for example a guide lug or a guide slot, that engages another guide feature, for example a guide slot or a guide lug that is provided in the housing 13. The dose element 17 is preferably secured against rotational movement with respect to the housing 13. In the embodiment shown in FIG. 2, the dose element 17 comprises ribs 19 on its outer surface 20. The housing 13 comprises grooves (not explicitly shown) on its inner surface. The ribs 19 of the dose element 17 and the grooves of the housing 13 are enabled to interact with each other. The ribs 19 extend linear along a longitudinal axis of the device 1.

(32) The ribs 19 of the dose member and the corresponding grooves of the housing 13 prevent the dose member 16 from rotational movement with respect to the housing 13. The dose member 16 is enabled to move in the proximal direction with respect to the housing 13 during dose setting. The dose member 16 is enabled to move in the distal direction with respect to the housing 13 during dose dispensing.

(33) FIG. 3 shows a more detailed view of the dose member 16. The dose member 16 comprises a first feedback element. In particular, the dose sleeve 18 comprises a helical groove 21 on its outer surface 22 wherein the helical groove 21 is the first feedback element of the drive mechanism 3.

(34) Further, the drive mechanism comprises an axially fixed element 29 comprising a second feedback element 30. The axially fixed element 29 may comprise a cylinder 38. Said cylinder 38 may comprise a protrusion. In particular, said cylinder 38 may comprise the second feedback element 30 which may be configured as a peg 39 that extends inwardly in the radial direction as shown in FIG. 2. The radial direction may be defined as a direction perpendicular to an axis connecting the distal end 7 and the proximal end 8 of the device.

(35) In FIG. 2, a main part of the cylinder 38 is shown as transparent to enable the peg 39 to be visible. Furthermore, the drive mechanism may comprise a nut component 36. The nut component 36 and the cylinder 38 are in a ratcheted engagement. In particular, the cylinder 38 may be enabled to rotate in a first angular direction relative to the nut component 36. If the cylinder 38 rotates in a second angular direction, the nut component 36 is rotated relative to the housing 13 such that the cylinder 38 and the nut component 36 do not rotate relative to each other. Moreover, the nut component 36 is engaged to the piston rod 12, e.g. by a threaded or splined engagement.

(36) The part of cylinder 38 which is visible in FIG. 2 comprises a ridge 33 extending outwardly in the radial direction. The ridge 33 may be ring-shaped. Further, the housing 13 comprises a groove 34 on its inside. The groove 34 may be ring-shaped. The ridge 33 of the cylinder 38 is engaged in the groove 34 of the housing 13 such that an axial movement of the cylinder 38 relative to the housing 13 is prevented during dose setting and dose dispensing operations.

(37) The axially fixed element 29 comprising the second feedback element 30 has a larger diameter than the dose sleeve 18. The element 29 surrounds the outer surface 22 of the dose sleeve 18. Moreover, the axially fixed element 29 comprises the peg 39 which extends inwardly in the radial direction from the axially fixed element 29.

(38) The second feedback element 30 is prevented from axial movement relative to the housing 13. Further, the second feedback element 30 is enabled to rotate relative to the housing 13.

(39) The peg 39 engages with the helical groove 21 of the dose sleeve 18. The helical groove 21 comprises a first and a second sidewall 24, 25. Preferably, the width of the peg 39 is slightly smaller than the distance between the two sidewalls 24, 25. Accordingly, the peg 39 can slide along the helical groove 21, if the dose sleeve 18 is moved along the longitudinal axis. Thereby, a linear movement of the dose sleeve 18 is converted into a rotational movement of the second feedback element 30 and the axially fixed element 29.

(40) A track of the helical groove 21 extends from a distal end 31 to a proximal end 32 of the groove 21. During a dose setting operation the peg 39 may be moved from the distal end 31 of the track to the proximal end 32 of the track. Accordingly, during a dose dispensing operation the peg 39 may be moved from the proximal end 32 of the track to the distal end 31 of the track.

(41) Further, during dose setting, the dose member 16 may be decoupled from the piston rod 12. During dose setting, the dose member 16 is moved in the proximal direction. Accordingly, the peg 39 slides along the helical groove 21. Thereby, an axial movement of the dose member 16 is transferred into a rotation of the cylinder 38. The cylinder 38 is rotated in a first angular direction. The cylinder 38 is engaged to the nut component 36 such that rotation of the cylinder 38 in the first angular direction is not transferred to the nut component 36. Accordingly, the nut component 36 is not moved during dose setting.

(42) However, during dose dispensing, the dose member 16 interacts with the piston rod 12. The dose member 16 can either engage directly with the piston rod 12 or the dose member 16 may engage with a drive member, e.g. a drive sleeve, engaging with the piston rod 12. Thereby, a movement of the dose member 16 in the distal direction is transferred into a movement of the drive member. The drive member may also move linearly in the distal direction or the drive member may carry out a rotational movement around the longitudinal axis of the housing 13.

(43) Furthermore, during a dose dispense operation of the dose member 16, a distal movement of the dose member 16 is transferred into a movement of the piston rod 12. In particular, a distal movement of the dose member 16 may be transferred into a rotational movement of cylinder 38 relative to the housing 13 as the peg 30 slides along the helical groove 21. The cylinder 38 is rotated anti-clockwise. The cylinder 38 is engaged to the nut component 36, e.g. by a ratchet connection, such that a rotation of the cylinder 38 in a second angular direction is transferred into a rotation of the nut component 36.

(44) The piston rod 12 may be either splined or threadedly engaged to the nut component 36. Further, the piston rod 12 has a threaded or splined connection to the housing 13. If the piston rod 12 is threadedly engaged to the nut component 36 and the piston rod 12 is splined to the housing 13, a rotation of the nut component 36 does not rotate the piston rod 12, but advances the piston rod 12 distally. If the piston rod 12 is splined to the nut component 36 and threaded to the housing 13, then the piston rod 12 will be rotated and advance distally if the nut component 36 rotates.

(45) When the piston rod 12 is moved into the distal direction, the piston rod 12 pushes the piston 10 into the cartridge 4 in the distal direction.

(46) The distance by which the piston rod 12 is moved corresponds to the delivered dose. This distance is defined by the amount of rotation of the nut component 36. The amount of rotation of the nut component 36 is determined by the relative angular positions of the the proximal end 32 and distal end 31 of the track of the helical groove corresponding to the start and finish positions of the peg 30 in the groove 21.

(47) FIG. 3 shows a dose member 16 comprising a dose element 17 and a dose sleeve 18 wherein the dose sleeve 18 is fixed to the dose element 17. The dose element 17 comprises ribs 19 on its outer surface 20 thereby enabling an axial movement of the dose member 16 relative to the housing 13 and preventing a rotational movement of the dose member 16 relative to the housing 13. The dose sleeve 18 comprises helical grooves 21 on its outer surface 22 thereby enabling an interaction of the dose member 16 with the second feedback element wherein an axial movement of the dose member 16 relative to the housing 13 is converted into a rotational movement of the second feedback element relative to the housing 13. The helical groove 21 comprises a first and a second sidewall 24, 25 and a bottom 26. At least one of a first and a second sidewall 24, 25 and a bottom 26 may comprise a structured surface.

(48) In an alternative embodiment, the second feedback 30 element may be part of a member positioned inside the dose sleeve 18. As an example, the second feedback 30 may be provided by a drive member, in particular it may be part of a drive sleeve. In this case, the second feedback element 30 may be positioned inside the dose sleeve 18. The first feedback element may be provided on another member positioned inside the dose sleeve 18 or on the inner surface of the dose sleeve 18.

(49) In particular, the feedback mechanism could be a mechanism separate from the drive mechanism. In particular, the first and second feedback elements could be provided by member separate from the drive member and the dose member. In the case that the feedback mechanism is separate from the drive mechanism, the feedback performance could be made independent of the drive force. As an example, the first and second feedback elements could be pressed together with a controlled force provided by a spring.

(50) However, if the feedback mechanism is integrated into the drive mechanism, fewer parts may be necessary to construct the device.

(51) FIGS. 4 and 5 show a dose member 16 comprising a first feedback element according to a first embodiment. The dose member 16 comprises a dose element 17 and a dose sleeve 18. The dose element 17 comprises slots 23 on its outer surface 22. A user interacts directly with the outer surface 22. The slots 23 simplify the gripping of the dose element 17.

(52) The dose sleeve 18 comprises a helical groove 21 which comprises a first sidewall 24 with a first surface, a second sidewall 25 with a second surface and a bottom 26 with a third surface. The first surface of the first sidewall 24 is structured and the second surface of the second sidewall 25 is smooth. During dose setting, the dose member 16 moves in the proximal direction relative to the housing 13. Accordingly, during dose setting, the dose sleeve 18 moves in the proximal direction relative to the second feedback element 30 and the axially fixed element 29. Accordingly, the peg 39 will run on the second surface of the second sidewall 25 of the helical groove 21. As the second surface is smooth, no audible or tactile feedback is provided thereby.

(53) During dose dispensing, the peg 39 will run on the first surface of the first sidewall 24 as the dose sleeve 18 moves in the distal direction relative to the peg 39. The first surface of the first sidewall 24 comprises a structure. In the embodiment shown in FIGS. 4 and 5, the first surface of the first sidewall 24 comprises ribs 27.

(54) During a dose dispensing operation, the peg will contact the first surface of the first sidewall 24 comprising ribs 27, thereby causing a tactile sensation to be transmitted to a user. Accordingly, the interaction of the ribbed surface of the first sidewall 24 and the peg 39 provides tactile feedback to the user. Moreover, the interaction of the peg 39 and the ribbed surface of the first sidewall 24 of the helical groove 21 may also provide audible feedback.

(55) Accordingly, a dose member 16 according to the first embodiment provides non-visible feedback to a user only during a dose dispensing operation. During dose setting, no feedback is provided to the user.

(56) Alternatively, the surfaces of the sidewalls 24, 25 of the helical groove 21 may be chosen in a way that, during dose setting, the peg interacts with a structured surface and, during dose dispensing, the peg interacts with a smooth surface. Thereby, non-visible feedback is provided to a user during dose setting. No non-visible feedback is provided to a user during dose dispensing.

(57) In a further embodiment, sidewalls 24 and 25 each comprise a structured surface 24a and 25b, respectively (see FIG. 8). Thereby non-visible feedback can be provided to a user during both dose setting and dose dispensing.

(58) In the embodiment of the dose member 16 as shown in FIGS. 4 and 5, the ribs 27 are equally spaced apart from each other. Accordingly, during the whole time of a dose dispensing operation, the same feedback is provided to the user.

(59) It is also possible to configure the first feedback element such that ribs 27 differ in size and/or spacing along a track of the helical groove 21. For example, the ribs 27 can be spaced further apart from each other at the proximal end 32 of the track of the helical groove 21 than at the distal end 31 of the track of the helical groove 21. Accordingly, at the beginning of the dose dispensing operation, the peg interacts with ribs 27 that are spaced further apart. Towards the end of the dose dispensing operation, the peg interacts with ribs 27 that are spaced closer together. This may give the illusion to the user that the dose member 16 is accelerating when the user pushes the dose member 16 in. Therefore, the users will slow the dispensing stroke down as the peg approaches the end of the track of the groove 21. Thereby the user may be prevented from overstraining the device 1.

(60) FIGS. 6 and 7 show a dose member 16 comprising a first feedback element according to a second embodiment. The dose member 16 differs from the dose member 16 shown in FIGS. 4 and 5 in that, here, the surfaces of the sidewalls 24, 25 of a helical groove 21 are smooth. Further, the surface of the bottom 26 of the helical groove 21 is ribbed. The mating peg interacts with the bottom 26 of the helical groove 21 during both dose setting and dose dispensing. Accordingly, during both operations, the peg is enabled to interact with a structured surface. Therefore, non-visible feedback is provided to a user during dose setting and during dose dispensing.

(61) Further variations of the feedback mechanism are possible. Additionally to a structured surface, a single rib to signal the end of the dose setting or dose dispensing operation could be provided at one end of the helical groove 21 on at least one of its surfaces. Further, a double rib to indicate that a complete dose has been set or dispensed could be provided at one end of the helical groove 21. This would alert the user through either a feeling and/or a sound that the limits of travel have been reached without the need for them to overstrain the device 1. The single rib and/or the double ribs may be provided either on a surface being smooth apart from said ribs or on a surface comprising further structure elements.