Assembly for a drug delivery device and method of operating the same

An assembly for a drug delivery device (200) is presented which comprises a housing (24) having a proximal end (25) and a distal end (26), a cartridge, a plunger (19) which is movably retained in the cartridge (14) and a piston rod (6). The assembly further comprises a rod displacement feature (33). The assembly is configured such that, in an initial state of the assembly, the piston rod (6) and the rod displacement feature (33) are arranged such that movement of the rod displacement feature (33) from the first position to the second position is transferred to the piston rod (6) such that the piston rod (6) is moved with respect to the cartridge (14) and the assembly is switched from the initial state to a primed state. In the primed state, movement of the rod displacement feature (33) from the first position to the second position is not transferred to the piston rod (6).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage application under 35 USC § 371 of International Application No. PCT/EP2014/065335, filed on Jul. 17, 2014, which claims priority to European Patent Application No. 13176861.6, filed on Jul. 17, 2013, the entire contents of which are incorporated herein by reference.

The present disclosure relates to an assembly for a drug delivery device, e.g. an injector-type device such as a pen-type device and a method of operating the same.

Drug delivery devices are, for example, known from U.S. Pat. No. 5,383,865 A, U.S. Pat. No. 7,699,815 B2 and WO 2006/089734 A1. It is an object of the present disclosure to provide an assembly for a drug delivery device which facilitates priming of the drug delivery device and to provide an associated method of operating the assembly.

This object is achieved by the subject-matter of the independent claims. Advantageous embodiments and refinements are subject-matter of the dependent claims.

One aspect of the present disclosure relates to an assembly for a drug delivery device comprising a housing having a proximal end and a distal end. The assembly further comprises a cartridge, a plunger being movably retained in the cartridge and a piston rod which is arranged to move the plunger distally with respect to the cartridge. The cartridge may contain a drug. The assembly further comprises a rod displacement feature which is movable between a first and a second position with respect to the housing. The assembly is configured such that, in an initial state of the assembly, the piston rod and the rod displacement feature are arranged such that movement of the rod displacement feature from the first position to the second position is transferred to the piston rod such that the piston rod is moved with respect to the cartridge and the assembly is switched from the initial state to a primed state. This embodiment enables the transfer of a force which may be applied by a user of the assembly via the rod displacement feature to the piston rod with respect to the cartridge such that the assembly is switched from the initial state to the primed state.

In an embodiment, the direction of movement of the rod displacement feature from the first to the second position is the distal direction. This embodiment allows for an expedient arrangement or design of the assembly, wherein the advantages mentioned in the present disclosure can be exploited easiest.

The assembly may form part of a drug delivery device. Alternatively, the assembly may be a drug delivery device. Preferably, the drug delivery device comprises the assembly, whereby a priming of the drug delivery device is enabled or facilitated. The initial state may be an as-fabricated state or an as-assembled state of the assembly. Preferably, in the initial state a user of the assembly has not yet carried out any actions concerning a function or preparation of the assembly. Particularly, the piston has not yet been moved such that a full initial dose of drug may be retained in the cartridge. In this state, there may be a considerable static friction between the plunger and the cartridge which originates from the manufacturing of the cartridge and/or storage of the plunger within the cartridge. Usually, such cartridges retaining a plunger are preassembled and mounted to further components of the assembly or a drug delivery device in a later step.

Preferably, the priming is carried out by the user of the assembly, e.g. via a dose button. Before the assembly has been primed, the user may already have set a dose of the drug delivery device or not. If the user has already set a dose, said dose or a corresponding dose may be dispensed by the drug delivery device when the drug delivery device is primed.

In an embodiment, in the primed state, movement of the rod displacement feature from the first position to the second position is not transferred to the piston rod. In other words, the rod displacement feature moves without interacting with the piston rod. The second position may exhibit a defined end position, wherein no further movement is possible. This embodiment provides the advantage that, when the assembly is primed such that movement of the rod displacement feature from the first to the second position has been transferred to the piston rod, said movement of the piston rod with respect to the cartridge does not occur during a subsequent movement of the rod displacement feature from the first position to the second position. In other words, priming essentially relates to an initial or first movement of the piston rod with respect to the cartridge. The assembly may be configured such that the piston rod interacts with the plunger during movement of the piston rod from the first position to the second position. Preferably, said priming may be carried out by a user of the assembly, via an actuation of further components of the assembly.

As the plunger is moved with respect to the cartridge during priming, a predetermined dose, e.g. a dose of drug such as a priming dose, may be dispensed from the drug delivery device during priming. Said dose may correspond to the distance the plunger is moved with respect to the cartridge.

In an embodiment, when the assembly is switched from the initial state to the primed state, the plunger is moved with respect to the cartridge and an initial static friction force between the plunger and the cartridge is overcome by the movement of the rod displacement feature from the first to the second position. As an advantage of this embodiment, any further movement of the plunger within the cartridge, e.g. during a dispensing operation of the drug delivery device may be carried out with less effort, as the initial static friction force has already been overcome.

In an embodiment, the assembly comprises a drive mechanism which is configured to transfer a driving force to the piston rod in the primed state. With the aid of the drive mechanism, the piston rod may be further moved, preferably in the distal direction, such that also the plunger is moved distally with respect to the cartridge, e.g. in order to dispense a dose of drug from the drug delivery device. The drive mechanism may be configured to drive the piston rod according to a set dose.

In an embodiment, the force required to move the plunger relative to the cartridge in the initial state, is the sum of the initial static friction force and the force necessary to push away or displace the liquid of drug from the cartridge. Said force is, expediently, greater than the driving force. Preferably, the initial static friction force is, in particular, also greater than the driving force.

In an embodiment, the initial static friction force is greater than the driving force. A minimum and a maximum driving force may be exertable by the drive mechanism. Furthermore, the driving force may take values from a range between the minimum and a maximum driving force. This provides the advantage that the drive mechanism may be designed to apply comparatively small forces to the piston rod, whereby a cost-effective and space-saving assembly is achieved. A further advantage relates to the fact that by a moderate force which is applied by the drive mechanism, further components or mechanisms of the assembly which require to overcome or temporarily to overcome the said force during an operation of the assembly may be configured simpler, cheaper and/or space-saving.

In an embodiment, the rod displacement feature is comprised by a displacement member of the drive mechanism, wherein the displacement member is movable to selectively couple a drive member to the piston rod in order to transfer the driving force to the piston rod. According to this embodiment, the assembly may be designed with a comparable low number of interacting parts, as said displacement member provides for the feature of the rod displacement feature, whereby the displacement member is also involved in a coupling to the piston rod via the drive member which may be required by the assembly to function properly.

In an embodiment the assembly comprises a spring element which is arranged and configured such that movement of the rod displacement feature from the first to the second position loads or biases the spring element and the spring force of the spring element tends to move the rod displacement feature back into the first position. Thereby, it may be achieved that after the rod displacement feature has been moved to the second position, it may be automatically repulsed by the spring force of the spring element such that, e.g. the user of the assembly may again operate the assembly.

In an embodiment, the assembly comprises a drive spring which is arranged and configured to drive the movement of the piston rod via the drive member by a driving force provided by a drive spring, whereby the driving force provided by the drive spring is exerted on the piston rod. The drive spring may be a torsion spring. During a setting operation of the drug delivery device, the drive spring may be loaded, and during a dispensing operation of the drug delivery device, the spring energy of the biased drive spring may be used to drive the piston rod.

In an embodiment, the assembly comprises a dose button being arranged and configured such that movement of the dose button with respect to the housing initiates a delivery of a dose of drug. Said movement, preferably being a distal movement is at least partly transferred to the rod displacement feature. Via the dose button, the user may advantageously move the rod displacement feature distally with respect to the cartridge. If the assembly is in the initial state, the user may thus prime the assembly via the dose button. When the assembly is in the primed state, the user may effect a dose setting, a cancelling or decreasing the size of a dose or a dose dispensing of the drug from the drug delivery device via the dose button. The assembly may be configured that for a dose setting, the dose button has to be rotated with respect to the housing while for a dose dispensing, the dose button has to be actuated such as depressed with respect to the housing.

In an embodiment, the assembly comprises a coupling element, wherein a unidirectional coupling is formed between the piston rod and the coupling element. The coupling element is fixed to the housing and arranged and configured such that a proximal movement of the piston rod with respect to the housing is prevented. This embodiment provides the advantage that, a reset of the piston rod and/or a misuse of the drug delivery device is prevented. Furthermore, it may be prevented that any substance can re-enter the cartridge. By this means, safety aspects of the assembly and/or the drug delivery device may be accounted for.

In an embodiment, the assembly is configured such that the user can replace the cartridge and reset the piston rod. This provides the advantage that the drug delivery device can be used for more than one cartridge sequentially.

In an embodiment, in the initial state, an initial content of the drug is retained in the cartridge. The initial content preferably relates to a maximum amount or content of drug which can be retained in the cartridge.

In an embodiment, in the initial state, the distance between a proximal face of piston rod and a distal face of the rod displacement feature is smaller than the distance between the first and the second position. According to this embodiment, it is assured that during movement of the rod displacement feature from the first position to the second position, the piston rod is effectively moved with respect to the cartridge, as the rod displacement feature may then abut the piston rod.

In an embodiment, in the initial state, a distance between the plunger and the piston rod is smaller than a distance between the first position and the second position of the rod displacement feature. The distance may result from manufacturing tolerances. The distance by which the rod displacement feature is moved may compensate manufacturing tolerances. By means of said movement, it may be ensured that the plunger and the piston rod abut in the primed state. According to this embodiment, it is assured as well that during movement of the rod displacement feature from the first position to the second position, the piston rod is effectively moved with respect to the cartridge.

In an embodiment, the plunger and the cartridge are configured such that the initial static friction force takes values between 10 Newtons and 20 Newtons.

In an embodiment, the drive mechanism is configured such that the driving force takes values between 3 Newtons and 10 Newtons.

A further aspect of the present disclosure relates to a method of operating the assembly comprising the steps of providing an assembly in an initial state. The assembly comprises a housing having a proximal end and a distal end, a cartridge, a plunger being movably retained in the cartridge, a piston rod arranged to move the plunger distally with respect to the cartridge and a rod displacement feature being movable between the first and the second position with respect to the housing. The method further comprises moving the rod displacement feature from the first position to the second position with respect to the housing, wherein said movement is transferred to the piston rod such that the piston rod is moved with respect to the cartridge and the assembly is switched from the initial state to the primed state. The method further comprises moving the rod displacement feature from the first position to the second position with respect to the housing, wherein said movement is not transferred to the piston rod. Said movement of the rod displacement feature from the first position to the second preferably occurs every time the dose button is depressed, e.g. to initiate a delivery action.

Features which are described herein above and below in conjunction with different aspects or embodiments may also apply for other aspects and embodiments.

Particularly, features described with respect to the arrangement may apply for the method, the unit and the module and vice versa.

Like elements, elements of the same kind and identically acting elements may be provided with the same reference numerals in the figures. Additionally, the figures may be not true to scale. Rather, certain features may be depicted in an exaggerated fashion for better illustration of important principles.

FIG. 1shows a perspective view of a drug delivery device200. The drug delivery device may be a disposable drug delivery device. The drug delivery device200comprises a housing24which houses further components. Only one half of the housing24is shown inFIG. 1such that inner components of the drug delivery device200are visible. The drug delivery device200further comprises a drive member1and a piston rod6. The piston rod may have a cross-section resembling a square, rectangle, parallelogram, circle or ellipse.

The drive member1is configured to move the piston rod6in a distal direction, e.g.

during a dose delivery of the drug delivery device200. The drug delivery device200comprises a longitudinal axis x, a distal end25and a proximal end26. Preferably, the longitudinal axis x extends through the distal end25and the proximal end26. In other words, the distal end25and the proximal end26may be spaced along the longitudinal axis. The drug delivery device200further comprises a, preferably replaceable, cartridge14in which a plunger19is retained. The piston rod6may be arranged next to or abut the plunger19. The cartridge14may further contain a drug31or medical substance to be dispensed from the drug delivery device200. The drug31may be dispensed in measured doses. The drug31may be retained in the cartridge14. The cartridge14may contain1.5ml or3ml of the drug31. Preferably, the cartridge14is arranged or aligned longitudinally. The piston rod6may also be arranged or retained longitudinally such that it is movable with respect to the cartridge14. The drug delivery device200further comprises a dose member2which may effect a dose setting and a dose dispensing of the drug delivery device. The dose member2is threadedly engaged with the drive member1, e.g. via an outer thread22. Accordingly, the drive member1may comprise an inner thread matching with the outer thread22. Thereby, said threaded engagement may be configured such that during a rotation of the dose member2with respect to the housing24, the drive member1is axially moved. In a setting mode of operation, the dose member is rotatable in a first or second direction with respect to the housing to set a dose and in a dispensing mode of operation, the dose member2is rotatable in a second direction opposite to the first direction with respect to the housing to dispense a set dose. The drug delivery device200further comprises a displacement member3which may be configured to displace or to contribute to the displacement of the drive member1.

The dose member2and the displacement member3are preferably aligned parallel to the longitudinal axis x but arranged radially offset from the cartridge14and the piston rod6. Drive member1may at least partially be arranged between the piston rod6and the dose member2. A longitudinal axis of the drive member may thereby be aligned radially. The dose member2and the displacement member3may comprise an elongate shape, respectively. The displacement member3is engaged to the drive member1via a guidance27of drive member1. The guidance27may be configured such that, e.g., when the dose member2is rotated, the drive member1is rotationally locked with respect to the displacement member3such that the dose member2and the drive member1are rotated relative to each other. The drug delivery device200further comprises a spring element4and a dose button5. The spring element4is retained between a pinion11of the dose member2and the dose button5. The displacement member3comprises a drive member displacement member50which comprises an elongate shape and which is aligned parallel to the longitudinal axis x. The length of the drive member displacement member50may relate to the travel of the drive member1and in this way to the amount of drug31to be dispensed during the dispensing of drug from the filled cartridge. The drive member displacement member50is retained by the guidance27. Preferably, the guidance27rotationally and radially locks the drive member displacement member50, whereby only relative axial movement of said components is allowed.

The displacement member3comprises a rod displacement feature30. In the depicted situation, the drug delivery device200is in an initial state. During the first use of the drug delivery device200, the rod displacement feature30may abut the piston rod6.

The drug delivery device200further comprises an indication assembly100. The indication assembly100comprises a first indication member110and a second indication member120. The piston rod6extends through the first and the second indication members110,120. The indication assembly100further comprises a locking member130which is configured to rotationally lock the first and the second indication member110,120with respect to the housing24. The drug delivery device200further comprises a guide feature23which is fixed to the housing24. When, e.g. the dose button5is moved distally, the displacement member3is also moved distally against the resilience of the spring element4. Thereby, the displacement member3is guided by the guide feature23which is engaged to a bore28of the displacement member3. Via the bore28and the guide feature23, an axial movement of the displacement member3may at least partly be converted into a radial movement of the displacement member3and/or the drive member displacement member50. The displacement member3may comprise a certain flexibility.

The drug delivery device200further comprises a drive spring13which is configured such that it is loaded upon a rotation of the dose member2in a first direction (cf. arrow29). To this effect, a distal end of the drive spring13is preferably fixed to the housing24and a proximal end of the drive spring13is preferably fixed to, e.g. a distal end of the dose member2. The drive spring13is a torsion spring. During setting of a dose of drug31, the drive spring13is loaded and spring energy is stored which can be used for a delivery of the drug31. The displacement member3is rotationally locked with respect to the housing24. In the setting mode of operation, the dose button5is rotated in the first direction29. The dose button5is connected to the dose member2, wherein said connection is configured such that the dose member2is also rotated in the first direction along with the dose button5, such that the drive spring13is loaded. Due to the threaded engagement of the dose member2and the drive member1, in the setting mode of operation, the drive member1is moved proximally while in the dispensing mode of operation, the drive member1is moved distally. In the setting mode of operation, the dose button5may also be rotated in a second direction (cf. arrow32) opposite to the first direction29in order to decrease or cancel a set dose of drug31. This would move drive member1distally. The dose button may be operated, e.g. rotated to dial the size of a dose to be delivered. The size may span a range between zero units and a maximum number of gradations or units, e.g.120.

The displacement member3and the dose member2are coupled via a releasable clutch mechanism by which said components are rotationally lockable. The releasable clutch mechanism is configured to withstand the spring force of the drive spring when a dose is set. When a maximum settable dose is set, the releasable clutch mechanism has to withstand a maximum spring force. The releasable clutch mechanism can be released by distal movement or depressing of the dose button5with respect to the housing24. Thereby, the displacement member3and the dose member2are disengaged (cf.FIG. 3further below).

The spring element4biases the releasable clutch mechanism towards the engaged state. In the setting mode of operation, the drive member is preferably in a first position, wherein it is disengaged from the piston rod6. When the dose button5is depressed or moved distally which is preferably manually performed by a user of the drug delivery device200, it is preferably switched from the setting mode to the dispensing mode of operation. During distal movement of the dose button5and the displacement member3with respect to the housing24, the displacement member3is guided via the guide feature23in such a manner that the displacement member3displaces the drive member1radially, i.e. towards the piston rod6such that the piston rod6is displaced from the first to a second position. In the second position, the drive member1is engaged to the piston rod6. The drive mechanism is preferably configured such that at the same time or slightly after the drive member1has engaged the piston rod , the releasable clutch mechanism is released and the spring force of the loaded drive spring13drives the dose member2such that the dose member2is rotated in the second direction32. The drive spring13is preferably configured to provide for a sufficient spring force for a minimum dose of drug31to be dispensed from the drug delivery device200when the piston rod6is in the second position. Due to the threaded interaction of the dose member2and the drive member1, the drive member1is moved distally with respect to the piston rod6when the dose member2rotates. The piston rod6comprises a piston rod feature17and the drive member1comprises a drive feature15(cf.FIG. 2). By an engagement of the drive feature15with the piston rod feature17, a distal movement of the drive member1may be transferred to the piston rod6such that the piston rod6is moved distally with respect to the housing24. Consequently, the plunger19is moved distally inside the cartridge14in order to dispense drug31from the drug delivery device200. The drug delivery device200further comprises a coupling element16which is configured such that the piston rod6is prevented from being moved in the proximal direction. When the dose button5is released either during or after a dispensing operation, the releasable clutch mechanism is reengaged and the drive member1is moved back from the second into the first position thus switching the drive mechanism back into the setting mode of operation. The drug delivery device200may be an injector-type device comprising a needle or a needle assembly (not explicitly indicated) which may be provided at the distal end25. Furthermore, the drug delivery device200may comprise a cap (not explicitly indicated) to cover the distal end25. The dose button5may need to be rotated six times during setting of a dose. This may correspond to a set dose of 120 units of drug31to be dispensed.

In the following, a priming mechanism is described by which the drug delivery device200may be switched from an initial state to a primed state. In the initial state, the drug delivery device200is preferably in an as-fabricated or as-assembled state, wherein the dose button5has not yet been actuated or pressed. Then, the cartridge14preferably contains an initial amount of drug31. The rod displacement feature30is axially movable between a first position and a second position. Expediently, the second position is distally offset from the first position. In the initial state, the piston rod6and the rod displacement feature30are arranged such that some or all of the movement of the rod displacement feature30from the first position to the second position is transferred to the piston rod6such that the piston rod6is moved with respect to the cartridge14. In the primed state, axial movement of the rod displacement feature30from the first position to the second position is not transferred to the piston rod6. Particularly, when the dose button5is in the initial state, a proximal face47of the piston rod6and a distal face46of the rod displacement feature30preferably abut (cf. alsoFIG. 6). Alternatively, the distance between the proximal face47of the piston rod6and a distal face46of the rod displacement feature30is at least smaller than the distance between the first and the second position. When, in the initial state, the dose button5is pressed by the user for the first time, the rod displacement member30is moved axially, thereby moving or advancing the piston rod6distally with respect to the cartridge14. Expediently, a needle is provided which in turn provides fluid communication between the interior of the cartridge14and the outside. The dose button5is moved until the rod displacement feature30is arranged in the second position, whereby an initial static friction force between the plunger19and the cartridge14is overcome. Thereby, the drug delivery device200is primed. The priming operation may additionally comprise the removal of clearances and/or tolerances and the application of compression or tension to further device components such that the device is prepared for an operation with no or only a minimum play between elements of the drive mechanism. The use of force transferred from the rod displacement member30to the piston rod6may help the drive mechanism to overcome initial static friction forces, particularly between the plunger19and the cartridge14.

In the primed state, the driving force is preferably sufficient to move or advance the piston19distally with respect to the cartridge14. As an advantage, the drive spring13may be designed smaller and more efficient with respect to costs and space requirements. In the initial state, the distance between the piston rod6and the rod displacement feature30is preferably greater than a manufacturing tolerance of the cartridge14and/or the piston rod14. Thereby, it is assured, that the direct distal movement of the rod displacement feature—which is effected manually by the user—is effectively transferred to the piston rod6. Preferably, the plunger19and the cartridge14are configured such that the initial static friction force takes values between 10 N and 20 N. Preferably, the mentioned drive mechanism is configured such that the driving force takes values between 3 N and 10 N.

The distance by which the dose button5is depressed may be 3 to 4 mm. The rod displacement feature30may be moved axially between the first and the second position. The distance the rod displacement feature30is moved axially may be 2 mm. Additionally, there may be a play or clearance of distance B of 1 to 2 mm between the dose button5and the displacement member3(cf.FIG. 6). To this effect, a further biasing member (not explicitly indicated) may be provisioned which tends to separate the mentioned components accordingly.

An advantage of the described priming functionality pertains to the effect that once the drug delivery device200is primed, the user may repeat the actuation or depressing of the dose button5if he is not sure about the state of the device. By means of the force necessary to depress the dose button5, the user will immediately realize whether the device has already been primed or not. Thereby, it is contributed to a simple and safe operation of the drug delivery device200. The presented drug delivery device200provides the advantages of, for instance, a comfortable, user-friendly shape, a low injection force owing to the priming mechanism, semi-automatic injection and the possibility to assemble the drug delivery device in an easy way. Moreover, the drug delivery device may be easily distinguished from other devices due to its characteristic shape. That is to say, the shape of the drug delivery device may deviate slightly from a cylinder-like shape which is usual for similar drug delivery devices. To this effect, it may be easier to hold it in the palm of the user's hand and/or to operate the drug delivery device.

FIG. 2illustrates a coupling between the piston rod6and the coupling element16by means of theFIGS. 2ato 2c. Drive feature15of the drive member2may constitute a plurality of drive features15which are shown each with a tilt towards the distal end25. The depicted situation respectively relates to the setting mode of operation, wherein the drive features15are disengaged from the piston rod6. The coupling element16is preferably fixed to or integrally formed with the housing24. The coupling element16comprises three axially spaced coupling features20each of which comprises teeth41. The coupling features20are also tilted towards the distal end25. The piston rod6comprises a set of teeth40which exhibit the piston rod feature17. The teeth40are configured uniformly and arranged equidistantly. Furthermore, the teeth40may be arranged at an inwardly directed, as well as an outwardly directed side surface of the piston rod6. The side surfaces of the piston rod6may be flat or non-flat, such as even. Each of the coupling features20is configured to establish a unidirectional coupling with the teeth40such that a proximal movement of the piston rod6with respect to the housing24is prevented. InFIG. 2a, only the coupling feature20bin the middle establishes said unidirectional coupling, as proximal end faces of the teeth40abut distal end faces of teeth41of that coupling element while this is not the case for the other coupling features20b, c. The distance between the proximal end faces of two adjacent teeth40of the piston rod6is indicated by A. The axial distance between the coupling features20is chosen such that the distance D between a distal end face of a tooth41of the coupling feature20cwhich does not establish the unidirectional coupling and a proximal end face of a tooth40of the piston rod6feature is smaller than the distance A. Preferably, the distance D corresponds to a minimum amount of a drug31to be dispensed from the delivery device200. The distance D is preferably defined by those teeth42of the piston rod6which are arranged proximally next to the respective tooth41of the respective coupling element. The distance D corresponding to a minimum amount of a drug31to be dispensed is expediently smaller than the distance A. Consequently, the piston rod6may be moved distally with respect to the coupling element16by a distance smaller than the distance A. InFIG. 2b, as compared to theFIG. 2a, the piston rod6has been moved distally (to the left) with respect to the coupling element16by the distance D. Thereby, the proximal end faces of the teeth40of the piston rod6have been moved out of abutment with the distal end faces of the teeth41of the middle coupling feature20band proximal end faces of the teeth40abut distal end faces of the left coupling feature20asuch that only this coupling feature establishes unidirectional coupling to the piston rod6. InFIG. 2c, the piston rod6has been moved further axially by the distance D′, as compared toFIG. 2b. As a consequence, only the right coupling feature20cforms the mentioned unidirectional coupling to the piston rod6. The distance D′ may relate to the distance D.

The drive features15of the drive member1are axially spaced, wherein each drive feature15comprises teeth42being configured to be engagable with the teeth40of the piston rod6, wherein the drive features15and the teeth42are configured such that when the drive member2is in the second position, a distal end faces of a teeth42of one of the drive features15abut proximal end faces of teeth40of the piston rod6and distal end faces of a teeth42of another drive feature15are spaced preferably by the distance D from proximal end faces of a teeth40of the piston6.

The functionality which is described herein by means of three teeth41may also function with coupling features and drive features which only comprise one tooth each. However, the provision of a plurality of teeth adds greater strength and some redundancy in the case of failure.

FIG. 3ashows a partial perspective view of inner components of the drug delivery device200in the setting mode of operation. The displacement member3comprises a clutch feature33which is, in the depicted situation, engaged to the pinion11of the dose member2. In this situation, the releasable clutch mechanism is engaged. The pinion comprises teeth48. The clutch feature33is a tooth-like clutch feature which is engaged or splined to the teeth48(cf. dashed circle). Although the dose member2may be selectively rotationally locked with respect to the housing24against the spring force of the drive spring13, it may still be rotated, e.g. by a rotation of the dose button5with respect to the housing24which is performed by the user. During a setting operation, particularly during a clockwise rotation (cf. arrow29inFIG. 1) of the dose member2with respect to the displacement member3, said clutch interaction between the clutch feature33and the pinion11may be overcome by the user. The torque required to set a dose may be 13.4 mNm for a set dose of zero and 25.4 mNm for a set dose of 120 units. The torque required to decrease or cancel a dose may be 16.8 mNm for a minimum dose and 4.8 mNm for the maximum settable dose. Expediently, said torques are larger than the torque which is applied to the dose member2by the drive spring13.FIG. 3bshows the situation in the dispensing mode of operation, wherein the clutch feature33has been disengaged from the teeth48of the pinion11, by movement of the dose button5with respect to the housing24. As compared toFIG. 3a, also the displacement member3has been moved distally with respect to the dose member2. Consequently, inFIG. 3b, the dose member2is free to rotate with respect to the displacement member3. In this situation, it is enabled that the drive spring13drives the dose member2in the second direction or counter clockwise (cf. arrow32inFIG. 1) by rotation.

FIG. 4shows parts of components of the drug delivery device200near the proximal end26. In the setting mode of operation, the dose button5is rotationally locked to the dose member2by a dose member spline35which is retained in a recess34of the dose button5such that the dose member2is rotated along with the dose button5. In the dispensing mode of operation, the dose member2is free to rotate with respect to the dose button5. To this effect, the dose member spline35and the recesses34are configured such that when the dose button5is moved distally with respect to the dose member2, e.g. during a dispensing operation, the dose member spline35is disengaged from the corresponding recess34and the dose member2is free to rotate with respect to the dose button5. When the dose button5is released again, e.g. during or after a dispensing operation, the dose member spline35is reengaged to one of the recesses34, e.g. to that recess which is arranged closest to the dose member spline35. This is due to the effect of the spring element4which biases the dose member2towards the distal end25.

FIG. 5shows a perspective view of components of the drug delivery device200illustrating, e.g. the function of a last dose mechanism of the drug delivery device200. A last dose ratchet37is provisioned to hinder, e.g. a user to set a further dose when the maximum settable dose is already reached or set. When a dose of a drug31is set, the drive member1moves away from the distal end25. When a dose is dispensed, the piston rod6moves distally with respect to the housing24together with the drive member1. The drive member1comprises a drive member arm39. The last dose ratchet37may be borne or retained by the pins43which may interact with a further component of the drug delivery device200or the housing24such that the last dose ratchet37is rotated around an axis defined by the pins43. The dose member2comprises a dose member ratchet38further comprising teeth44which are disposed on a circumferential face or another face. When a large or a maximum number of units has already been dispensed from the drug delivery device200and/or when a large or a maximum dose is set, the drive member arm39engages a ramp36near the proximal end26. Thereby, the drive member arm39is moved radially outwards, thus rotating the last dose ratchet37around the axis which extends through the pins43. Due to the rotation of the last dose ratchet37, an end portion45of the last dose ratchet37engages the teeth44of the dose member ratchet38such that the dose member2is prevented from rotation in the first direction29, i.e. the direction in which the set dose is increased. In the setting mode of operation, the dose member2may then be moved in the second direction (cf. arrow32inFIG. 1) in order to decrease or cancel the dose. Thereby, the drive member1is moved distally with respect to the piston rod6. When the maximum dose is set, the dose member2is thus prevented from being rotated in the first direction29to set an additional dose of drug31.

FIG. 6shows a partial side view of inner components of the drug delivery device200. In the depicted situation, the drug delivery device200is in an initial state and the rod displacement feature30abuts or is closely arranged to the piston rod6. When the dose button5is then moved or depressed in the distal direction by a distance B which may correspond to 1 mm, the dose button abuts the displacement member3. Upon further distal movement of the dose button5, the displacement member3and also the piston rod6is moved distally against the resilience of the spring element4. The indication assembly100is shown inFIG. 6in greater detail. The drug delivery device200may comprise a window21which may be comprised by the housing24. The dose member2comprises a first pinion9. The pinion11exhibits a second pinion, as mentioned above. The first indication member110further comprises a first corresponding pinion115which is engaged or engagable to the first pinion9. The first pinion9comprises a protrusion49. The second indication member120further comprises a second corresponding pinion125which is engaged to the second pinion11. The first and the second indication member110,120comprise indication numbers or symbols which, e.g. to indicate the size of a set dose. The first and the second indication members110,120are mechanically decoupled from one another. The dose member2may be suitable to drive the first and the second indication member110,120, particularly to rotate said components via the first and the second pinion9,11with respect to the housing24. The first indication member110may be incrementally rotatable such that when the dose member2is rotated by one revolution, the first indication member110is rotated by one increment due to an engagement of the protrusion49with the first corresponding pinion115. The locking member130may be rotationally locked with respect to the housing24of the drug delivery device200. Thereby, the housing24may be and/or act as a locking member guide. The first and the second indication members110,120are rotatable with respect to the locking member130. The axis of rotation may be an axis parallel to the longitudinal axis x of the drug delivery device200. The locking member130may be axially movable respect to the housing24. InFIG. 6, a rotation of the dose member2in the first direction would lead to a rotation of the second indication member120in the second direction such that the number1would be indicated through the window21. InFIG. 7the counting direction of the depicted numbers of the first and second indication member110,120is reversed for the sake of clarity.

By means ofFIG. 7the indication assembly100is described schematically and in greater detail. The indication assembly100may contribute to a display mechanism of the drug delivery device200which allows, e.g. for an indication and/or counting of set doses of the drug delivery device200. The first indication member110comprises a first indication feature111and the second indication member120comprises a second indication feature122which may be a recess. The first indication feature111comprises a guiding surface112and a stop face113. The locking member130comprises a first locking member feature131and a second locking member132. The first indication member110further comprises a cut-out114. The first and the second locking member feature131,132are arranged on opposite sides of the locking member130. The first and the second indication member110,120are at least partially arranged axially between the first and the second locking member feature131,132.

InFIG. 7a, a dose of zero units is indicated. The locking member130is arranged in the cut-out114. Via the cut-out the first indication member110is rotationally locked in the second direction with respect to the locking member130. The second indication member120further comprises a second interaction feature or stop121. The locking member130is arranged at an axial position, wherein it abuts the stop121, thereby simultaneously locking the second indication member120rotationally in the second direction with respect to the locking member130. This situation may correspond to an initial position of the locking member130, wherein the set dose is zero. The first and the second indication member110,120may comprise cylindrical indication surfaces. The first and the second locking member features131,132comprise one or more even surfaces which are arranged obliquely with respect to the axis of rotation of the first or the second indication member110,120. The first and the second indication member110,120may rotate around a common axis, preferably around the longitudinal axis x. When a dose of the drug delivery device200is set, the dose member2is rotated in the first direction via the dose button5such that this set dose may be indicated through the window21. Such rotation may relate to a rotation of the first and the second indication member110,120in a first rotational direction with respect to the locking member130. A rotation of the dose member2in the second direction relates, accordingly, to a rotation of the first and the second indication member110,120in a second rotational direction with respect to the locking member130. When a dose of the drug delivery device200is set, the second pinion11, drives the second corresponding pinion125of the second indication member120such that the set dose, i.e. the dose indicated by the indication assembly100increases. Thus, when, inFIG. 7, the indicated dose (which may correspond to the number in the middle) is increased, the indication assembly100and the dose member2are configured such that, when the second indication member120is rotated for one revolution, the first indication member110is rotated by an angle corresponding to one digit such that “1” is indicated instead of “0”. Thereby, the locking member130is moved axially and out of the cut-out114of the first indication member110. Now the locking member130is in a non-locking position, as, for example, shown inFIG. 7cby means of the indicated dose of51units. The locking member130is biased towards said non-locking position by a biasing member (not explicitly indicated) with respect to the first and the second indication members110,120. Preferably, the locking member is biased towards the initial position of the locking member130. When the maximum dose of, for example120units, is set (cf.FIG. 7b), which may correspond to a predetermined angle of the first and/or the second indication member110,120with respect to the locking member130, the first locking member feature131interacts with the first interaction feature111such that the locking member130is displaced into a locking position (cf.FIG. 7b) with respect to the indication member130, thereby rotationally locking the first and the second indication member110,120with respect to the locking member130in the first direction. The displacement of the locking member130with respect to the first and the second indication member110,120is an axial displacement, e.g. along the longitudinal axis x of the drug delivery device200(cf.FIG. 1). In the second direction, the first and the second indication member110,120are still rotatable with respect to the locking member130. The rotation in the second direction may relate to an operation of the drug delivery device200, wherein a dose is decreased or cancelled. The axial displacement of the locking member130is guided by the guiding surface112such that the second locking member feature132is axially displaced into the second indication feature122. InFIG. 7b, the locking member130abuts the stop face113. Now, the first and the second indication member110,120are rotationally locked in the first direction with respect to the locking member130. This situation may relate to an indication of the maximum settable dose (cf. “120” inFIG. 7b).

As an advantage of the presented indication assembly, a display or indication mechanism for the drug delivery device can be provided which functions with a low number mutually interacting components and thus the counting assembly can be embodied robust and safe.

An application of the presented indication assembly is not restricted to drug delivery device, but merely illustrated exemplarily by that means.

The end of a dose delivery action may be indicated by a feature (not explicitly indicated) which provides an audible feedback when further components of the drug delivery device move relative to one another.

The drug delivery device may additionally comprise components which are not explicitly indicated and/or the function of which is not described herein. For instance, the presented device may comprise a mechanism which decouples or ratchets the dose button relative to the dose member if an excessive torque is applied to the dose button by the user in the setting mode of operation.

Although this is not explicitly described herein, the actuation member and the displacement member may be embodied in a single component and the whole configuration of the drive mechanism and/or the device may be adjusted accordingly.

A further variant of the design may allow the user to decouple the coupling feature from the piston rod feature such that the piston rod can be moved axially, e.g. proximally, with respect to the housing. This is particularly advantageous when the drug delivery device is configured reusable such that the piston rod can be reset and the cartridge can be changed.

The drive mechanism may further comprise a clutch element which is configured to receive motion of the actuation member when the user attempts to set a dose greater than the maximum settable dose. This may be embodied by means of a torque limiter comprising, e.g. protrusions, recesses and/or resilient elements preventing destruction or damage of components of the drive mechanism and/or the drug delivery device when the user attempts to set a dose greater than the maximum settable dose.

The term “drug” or “substance”, as used herein, preferably means a pharmaceutical formulation containing at least one pharmaceutically active compound, wherein in one embodiment the pharmaceutically active compound has a molecular weight up to 1500 Da and/or is a peptide, a protein, a polysaccharide, a vaccine, a DNA, a RNA, an enzyme, an antibody or a fragment thereof, a hormone or an oligonucleotide, or a mixture of the above-mentioned pharmaceutically active compound,

There are five types of mammalian Ig heavy chain denoted by α, δ, ϵ, γ, and μ. The type of heavy chain present defines the isotype of antibody; these chains are found in IgA, IgD, IgE, IgG, and IgM antibodies, respectively.

The scope of protection of the invention is not limited to the examples given hereinabove. The invention is embodied in each novel characteristic and each combination of characteristics, which particularly includes every combination of any features which are stated in the claims, even if this feature or this combination of features is not explicitly stated in the claims or in the examples.

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