DRUG DELIVERY DEVICES

Description

The present disclosure relates to a drug delivery device. Particularly, the present disclosure relates to an arrangement of drug delivery devices and/or to a method for the modification of one drug delivery device or parts thereof to provide a different drug delivery device. The respective drug delivery device is preferably an injection device and/or a pen-type device, such as a pen-type injector.

In recent times, drug delivery devices, e.g. the ones which are used by medically non-trained users such as patients, have become very sophisticated with respect to the mechanisms which they use for dose setting and/or dose delivery. Users have become very accustomed to the way specific drug delivery devices operate and got to know advantages of certain types of devices and their dose setting and drive mechanisms. It is also not unheard of that users of drug delivery devices told their friends of the specific advantages and the friends, who might suffer from a different disease than the user, want to try the device, which has been recommended by their friend, but with a different drug or drug formulation which suits the needs of the friend.

Therefore, it is an object of the present disclosure to provide improvements associated with drug delivery devices, which are, preferably, modified for different purposes, e.g. for dispensing different drugs or drug formulations.

This object is achieved, for example, by the subject-matter defined in the independent claims and/or other subject-matter disclosed herein. Further advantageous solutions, embodiments and refinements are subject-matter of the dependent claims and/or of the following disclosure.

One aspect of the present disclosure relates to the drug delivery device. The drug delivery device, in the present disclosure, comprises a housing. The housing may have a proximal end and a distal end. The housing may have a tubular shape. The housing may define a section of the exterior shape or contour of the drug delivery device. The drug delivery device preferably further comprises a dose setting and drive mechanism. The dose setting and drive mechanism is expediently at least partly arranged in the housing. The dose setting and drive mechanism may comprise one or more mechanism members. The mechanism members are preferably movable relative to the housing and/or relative to one another during a dose setting operation and/or during a dose delivery operation. A dose setting operation may be an operation, where the size of a dose of liquid, which is to be dispensed from the drug delivery device is set. The size may be varied. Therefore, the drug delivery device may be a variable dose device. In the dose delivery operation, the previously set dose may be dispensed from the device.

A mechanism unit of the drug delivery device may comprise the housing and the dose setting and drive mechanism. The drug delivery device may be a resettable or reusable device. That is to say, after the content of a drug reservoir or cartridge has been emptied, the reservoir or cartridge may be replaced with a new reservoir or cartridge and the mechanism unit may be reused to dispense the drug from the new reservoir or cartridge. As opposed to the mechanism members, the housing may be static during the dose setting operation and the dose delivery operation, preferably also during a reset operation, when the mechanism is reset to an initial condition and ready to be used together with a new reservoir or cartridge. The respective mechanism member may move relative to the housing and/or relative to other mechanism members at least during the dose setting operation or the dose delivery operation or during both operations. The respective mechanism member may be static relative to the housing during only one of the dose setting operation and the dose delivery operation or move relative to the housing during the dose setting operation and the dose delivery operation.

The drug delivery device preferably comprises a cartridge unit, which is, preferably releasably or permanently, connected or connectable to the housing or retained in the housing. The cartridge unit may be configured to provide a cartridge and/or to connect the cartridge to the housing. The cartridge unit may comprise or may be provided to retain a cartridge containing a liquid, e.g. a drug or medicament. The cartridge may comprise a bung and a cartridge body. The bung may be movable in the distal direction relative to the cartridge body to dispense liquid from the cartridge. The liquid may be dispensed through a dispensing opening of the cartridge, which may be arranged at the distal end of the cartridge. The quantity of liquid in the cartridge may be sufficient for a plurality of doses to be dispensed form the drug delivery device. The dispensing opening may be closed by a septum, which may be pierced, e.g. by a needle, to provide fluid communication between the interior of the cartridge body and the exterior. The bung may seal the cartridge proximally. The cartridge unit may comprise a cartridge holder, in particular if the cartridge unit is connected to the housing either releasably or permanently, i.e. irreleasably. The cartridge may be arranged within the cartridge holder and preferably be retained therein. The cartridge may be permanently retained or secured in the cartridge holder. The cartridge holder may be releasably secured to the housing. If the cartridge is permanently secured in the cartridge holder, the cartridge unit may be a single disposable item or an item of consumable material, which is exchanged when the cartridge has been emptied. Thus, the cartridge may be protected by the cartridge holder all the time. Exchanging a cartridge within a cartridge holder can then be dispensed with. The entire cartridge unit may be disposed of after the cartridge has been emptied and replaced with a new cartridge unit. As an alternative to a cartridge unit which comprises the cartridge holder and the cartridge, the cartridge unit being connected to the housing, a cartridge retaining section may be defined in the housing, within which the cartridge unit, which then preferably consists of the cartridge, can be retained. If the housing has a cartridge retaining section in its interior, the housing may be unitary and/or may cover members of the dose setting and drive mechanism as well as the cartridge, the latter one preferably along its entire axial extension. The housing may have a generally tubular shape.

One aspect or the present disclosure relates to an arrangement of drug delivery devices. The arrangement comprises a first drug delivery device and a second drug delivery device. The arrangement may comprise further devices. The first and the second drug delivery device may have the features or parts discussed above, where the features or parts associated with the first device may be identified by the prefix“first” in the following text and in the claims and the features associated with the second drug delivery device may be identified by the prefix “second”. Thus, the first drug delivery device comprises a first housing and the second drug delivery device comprises a second housing and so on. When a drug delivery device is generally discussed or the features of drug delivery devices are described in general the prefix is usually not used. In this case, the first and/or the second drug delivery device may comprise the associated features. When discussing differences between the first drug delivery device and the second drug delivery device the prefixes may be used.

In an embodiment, the first mechanism members and the second mechanism members, that is to say the mechanism members of the dose setting and drive mechanisms of the first and second drug delivery devices, comprise at least one interchangeable mechanism member, e.g. one or more. The interchangeable mechanism member may be a member, which can be used to assemble both, the first dose setting and drive mechanism and the second dose setting and drive mechanism. When a mechanism member is an interchangeable mechanism member, advantageously no structural modifications have to be made to the member to be applied in the first drug delivery device and in the second drug delivery device. Thus, an interchangeable mechanism member can be used in both devices, without structural modifications and/or without changing the operation characteristics of the respective device. Interchangeable members may be structurally identical. The first and the second drug delivery device, in particular the first and second dose setting and drive mechanisms, may nevertheless be different. Having interchangeable members or parts in different drug delivery devices makes production of drug delivery devices more economic, as one specific component can be used for different devices.

In an embodiment, the first mechanism members and the second mechanism members each comprise at least one non-interchangeable or unique mechanism member, e.g. one or more. As opposed to the interchangeable mechanism member, a non-interchangeable mechanism member of one dose setting and drive mechanism cannot be used to assembly the other dose setting and drive mechanism. Via the non-interchangeable mechanism member, the respective drug delivery device may be adjusted to the specific liquid contained in the cartridge unit, for example different drugs or drug formulations. As opposed to interchangeable mechanism members, non-interchangeable mechanism members can only be used to assemble one of the first and second dose setting and drive mechanisms and not the other one. Accordingly, these members may be unique to the respective drug delivery device. For example, non-interchangeable mechanism members may be structurally different although they may be of the same type, e.g. piston rods, as will be discussed in more detail below. Interchangeable members may perform the same movements during dose setting and/or dose delivery, preferably not only the same types of movements but also by the same amount e.g. angular and/or axial displacement, with respect to the associated housing and/or with respect to the other mechanism members of the associated dose setting and drive mechanism. For example, interchangeable members may not change the way the mechanism operates and, in particular, may not alter the axial displacement of the bung relative to the cartridge body for a specific dose setting movement, e.g. by a specific angle and/or axial displacement, for setting of a particular dose. Non-interchangeable members, however, may have an effect on the axial displacement of the bung relative to the cartridge body. However, the non-interchangeable mechanism members expediently perform the same types of movement during dose setting and dose delivery as a mechanism member in the other dose setting and drive mechanism of the same type. Thus, on account of the non-interchangeable mechanism member(s) of the first dose setting and drive mechanism, the axial displacement of the bung relative to the cartridge body may be different for the first and second dose setting and drive mechanisms for the same dose setting movement, e.g. of the same rotation angle and/or axial displacement.

In an embodiment, the first and/or second mechanism members comprise a plurality of interchangeable mechanism members. Alternatively or additionally, the first and second mechanism members comprise a plurality of non-interchangeable mechanism members.

In an embodiment, the number of interchangeable mechanism members is greater than the number of non-interchangeable mechanism members. Accordingly, adjusting or modifying the dose setting and drive mechanism for a different drug delivery device may be facilitated by replacing just a few of the mechanism members and re-using interchangeable ones.

In an embodiment, the number of interchangeable mechanism members in the first and second dose setting and drive mechanism, which move relative to one another and/or relative to the first or second housing during the dose setting operation, is greater than the number of interchangeable members, which move relative to one another and/or to the first or second housing during the dose delivery operation. Preferably, the majority of mechanism members, which move or move significantly relative to the housing during the dose setting operation, , such as 55 % or more, 70% or more, or 90 % or more, and/or two or more, three or more, or four or more members, are interchangeable members. The proportion and/or number of interchangeable members, which move or move significantly relative to the housing during the dose delivery operation is preferably less than the one during the dose setting operation. This has the advantage that the feeling during the dose setting operation for a user can be kept constant even between different drug delivery devices and the adjustment can be largely made in the mechanism members which move during dose delivery. That is to say, for setting a dose, in particular a dose of a particular size, e.g. a particular amount of international units (IU), the movements which have to be performed may be same in the first and second drug delivery device, e.g. with respect to rotation angle and/or axial displacement. The adjustment to how much the bung is displaced relative to the cartridge body, which effectively corresponds to how much liquid is dispensed from the cartridge for a pre-defined dose setting movement of mechanism members, can be effected by adjusting the mechanism members, which move, preferably only or only significantly, during the dose delivery operation, i.e. by providing one or more non-interchangeable members in these members.

In an embodiment, the number of non-interchangeable mechanism members between the first and the second drug delivery device, is greater in the mechanism members which move, preferably only or only significantly, relative to one another and/or to the housing during the dose delivery operation than in the mechanism members which move, preferably only or only significantly, relative to one another and/or to the housing during the dose setting operation.

In an embodiment, the dose setting and drive mechanism of the (respective) drug delivery device may comprise any arbitrary one of, an arbitrarily selected plurality of, or all of the following members or types of members:

- A piston rod. The piston rod may be arranged to drive moment of the bung during the dose delivery operation. Thus, when the piston rod moves in the distal direction relative to the housing the bung may be displaced distally relative to the cartridge body. The piston rod may be a leadscrew or a tooth rod for example. The piston rod may be moved distally relative to the

housing during dose delivery. The piston rod may be prevented from movement, distally and/or proximally, during the dose setting operation.

- A bung interface member, e.g. a bearing. The bung interface member may be coupled to the piston rod, e.g. axially secured to the piston rod, and/or be configured to abut the bung. The piston rod may be rotatable relative to the bung interface member. If the piston rod rotates during dose delivery relative to the bung interface member, a separate bung interface member is advantageous, as the rotation of the piston rod is then not transferred to the bung. If the piston rod is only axially displaced, the piston rod may abut the bung immediately without a bung interface member associated with the piston rod, for example.

- A drive member. The drive member may be operatively coupled to, e.g. engaged with, the piston rod to transfer a driving force or torque to the piston rod, e.g. from the user to the piston rod. Thus, the drive member may be that element, e.g. the only element, of the dose setting and drive mechanism, which is directly coupled to the piston rod. When the drive member moves during the dose delivery operation this movement is preferably transferred to the piston rod to cause movement of the piston rod in the distal direction. The drive member may or may not move during the dose setting operation. The drive member may be a sleeve. The drive member may comprise a plurality of parts, which act as one part during dose setting and dose delivery.

- A dose setting member, e.g. a dial sleeve. The dose setting member is preferably movable relative to the housing in order to set a dose, e.g. the size of a dose of liquid to be delivered from the cartridge. The dose setting member may be a sleeve. The dose setting member may be rotatable and/or axially displaceable relative to the housing to set the size of a dose. The rotation angle and/or the axial displacement distance relative to the housing during the dose setting operation may be indicative for the size of the set dose. The dose setting member may move during dose setting and/or during dose delivery.

- A user interface member, e.g. one or more user interface members. The user interface member may be a button. The user interface member may be operable, e.g. touched and/or moved, by the user for performing the dose setting operation and/or the dose delivery operation. The dose setting operation and/or the dose delivery operation may use a common user interface member or use different user interface members. For example, one user interface member may be associated with a dose setting operation, e.g. the dose setting member, and another one, e.g. a button or trigger member, which is moveable relative to that user interface member, which moves during dose setting, for initiating and/or switching to the dose delivery operation.

- A tracking member. The tracking member may be coupleable or coupled to a tracking member path. The tracking member path, e.g. a thread, may be provided on the housing or on a mechanism member, e.g. the drive member, such as on one part thereof. During dose setting, there may be relative movement between the tracking member and the member on which the path is provided. The tracking member may be coupled to the dose setting member. In particular, movement of the dose setting member during the dose setting operation relative to the housing may be converted into movement of the tracking member relative to the tracking member path. The position of the tracking member along the tracking member path before dose setting is commenced may be indicative for the volume of liquid still available in the cartridge that is to say for the volume of liquid which is currently in the cartridge. If the tracking member is arranged in an initial position relative to the path, the cartridge may be full. When it is arranged in an end position, the cartridge may be considered empty. When the tracking member is in the end position, increasing the size of the currently set dose further may be prevented. However, a previously set dose, which may be less than the maximum settable dose, may still be delivered during a dose delivery operation. A tracking member of this kind is often also designated as last dose member and, as it is sometimes implemented as a nut traveling along a helicon path, as a last dose nut.

- A dose indication member. The dose indication member may be configured to indicate the size of the set dose. As the size of the dose may vary, the indication provided by the dose indication member may change. On an outer surface of the dose indication member indicia, e.g. numbers, may be provided to indicate the size of the currently set dose. The dose indication member may be a sleeve, such as a number sleeve, for example. The dose indication member may be coupled to the dose setting member, for example so as to convert movement of the dose setting member relative to the housing to set a dose into the movement of the dose indication member, where the size of the currently set dose, which is indicated by the dose indication member, changes as the dose setting member is operated to vary, e.g. increase or decrease, the currently set dose.

- A dosing clutch member. The dosing clutch member may be provided to couple two mechanism members of the dose setting and drive mechanism during one of the dose setting operation and the dose delivery operation, preferably during only one of the operations. Thus, during one of the operations, the clutch member may couple the two mechanism members and during the other one of the operations the members may be uncoupled. The coupling may be a rotational lock such that the members co-rotate during one of the operations and relative rotation between the members is allowed during the other operation.

- A reset clutch member. The reset clutch member may be provided to couple two mechanism members during the dose setting operation and the dose delivery operation. However, the coupling may be released for a reset operation that is to say an operation, which moves the piston rod, which has been displaced relative to the housing from an initial position towards an end position to empty the cartridge, back towards the initial position. If the two mechanism members are coupled by the reset clutch member, movement towards the initial position of the piston rod may be prevented. Thus, decoupling the two mechanism members may be mandatory for a reset operation. The two mechanism members may be permanently coupled to one another, e.g. rotationally and axially locked, during dose setting and dose delivery and be decoupled, preferably only, for the reset operation, e.g. when the cartridge unit has been disconnected from the mechanism unit. The two mechanism members coupled by the reset clutch member may be two parts of the drive member.

- A clicker member. The clicker member may be provided to generate an audible and/or tactile feedback. The feedback may be generated during the dose setting operation and/or the dose delivery operation. The feedback is preferably generated by a relative rotation between two parts during the relevant operation. One of the parts may be the clicker member and the other part may be another one of the mechanism members, which may rotate during the dose setting and/or the dose delivery operation, or the housing, for example.

The members discussed above may be unitary members, except where a multipart construction is explicitly disclosed and/or required for the function discussed in the context, e.g. for the drive member, which may have a plurality of parts, to provide a resettable or reusable device.

In an embodiment, the first dose setting and drive mechanism and the second dose setting and drive mechanism consist of first mechanism members and second mechanism members of mutually corresponding types of members. That is to say, if the first mechanism comprises a piston rod, so does the second and vice versa, for example. The same may hold for any one of the other types of mechanism members, which have been discussed above.

In an embodiment, the first liquid and the second liquid are different. Thus, the first cartridge and the second cartridge may be provided to dispense different liquids. The first liquid and the second liquid may comprise different drugs or different drug formulations. That is to say, the first liquid may comprise a first drug or drug formulation and the second liquid may comprise a second drug or drug formulation. Different drugs may mean different active pharmaceutical ingredients. Different drug formulations may mean that the first and second liquids may

comprise the same drug or active pharmaceutical ingredient, e.g. insulin, but in different concentrations.

In an embodiment, the first cartridge and the second cartridge have different dimensions. For example, the first cartridge body and the second cartridge body may have different lengths and/or diameters. The length of the cartridge may be the axial extension from the proximal end to the distal or dispensing end of the cartridge. The diameter may be the width of the cartridge in the radial direction. The diameter may be the maximum or minimum diameter and/or an inner diameter and/or an outer diameter of the cartridge, e.g. of the cartridge body. The first cartridge and the second cartridge may define different volumes. The first and the second cartridge may have different filling volumes or maximum volumes of liquid, which can be filled into the respective cartridge. The volume of the first cartridge or cartridge body may be less than the one of the second cartridge or cartridge body, preferably less than 80% or less than 60% of the one of the second cartridge body, e.g. 50% of the one of the second cartridge body. The first cartridge body may be shorter than the second cartridge body. The first cartridge body may have a smaller diameter than the second cartridge body. The first cartridge body may be a 1.5 ml. cartridge body and the second cartridge may be a 3.0 ml. cartridge body, for example. The number of International Units (IU) of the drug contained in the first cartridge may be greater than the number of International Units (IU) of the drug contained in the second cartridge. The first liquid may have a higher drug concentration than the second liquid. For example, the concentration in the first liquid may be greater than or equal to the one in the second liquid multiplied by any one of the following values: 1.5, 2, 2.5, 2.75, 3. Even though the volume of liquid provided in the first cartridge may be less than the one in the second cartridge, the number of available (international) units of drug in the first cartridge may still be greater than the one available in the second cartridge. For example, the first cartridge may contain 450 IU and the second cartridge 300 IU of a drug, such as insulin.

In an embodiment, any arbitrary one of, any arbitrarily selected plurality of, or all of the following members are non-interchangeable mechanism members, particularly if comprised by the first mechanism members and the second mechanism members:

- the piston rod;

- the bung interface member;

- the drive member; if the drive member is composed of a plurality of parts which operate as one part during dose setting and/or dose delivery, not all of the parts may be non-interchangeable; Preferably that part of the drive member, which interacts with the piston rod may be non-interchangeable, the remaining part(s) of the drive member may be interchangeable part(s); and/or

- the tracking member and/or the member on which the tracking path is provided, e.g. that part of the drive member which engages the piston rod.

The non-interchangeable mechanism members mentioned above may be particularly suitable for cartridges of different dimensions, different volumes, different filling levels, and/or different drugs or drug formulations.

In an embodiment, the first cartridge and the second cartridge may have the same dimensions and/or filling levels. The liquid contained in the cartridges may, however, be different. For example, the drug concentration in the first cartridge may be greater than the one in the second cartridge as indicated above. The initial volume of liquid in the cartridges may be the same.

In an embodiment, any arbitrary one of, any arbitrarily selected plurality of, or all of the following members are non-interchangeable mechanism members, particularly if comprised by the first mechanism members and the second mechanism members:

- the piston rod;

- the drive member, e.g. the distal part thereof;

- the tracking member;

- the dose indication member.

These non-interchangeable mechanism members may be particularly useful if the first and second cartridges have the same dimensions, filing levels and/or volumes but different drugs or drug formulations.

In an embodiment, the remaining mechanism members, i.e. the ones which are not expressly recited as being non-interchangeable further above, may be interchangeable mechanism members. Thus, even though the mechanism members of the first drug delivery device and the second drug delivery device may comprise a piston rod, the piston rod cannot be exchanged between the two drug delivery devices, for example. If the piston rod were attempted to be exchanged, the mechanism of the other device would jam or be severely damaged. The same consequences may ensue in the event it is attempted to use one of the further non-interchangeable mechanism members in the other mechanism.

In an embodiment, any arbitrary one of, any arbitrarily selected plurality of, or all of the following mechanism members are interchangeable members, particularly if comprised by the first mechanism members and the second mechanism members:

- one or more parts of the drive member, if the drive member comprises a plurality of parts; one part of the drive member is preferably non-interchangeable as discussed above;

- the dose setting member;

- the user interface member(s);

- the dose indication member;

- the dosing clutch member;

- the reset clutch member; and/or

- the clicker member.

These interchangeable mechanism members may be particularly useful if the first cartridge and the second cartridge have different dimensions, filling volumes, and/or different drugs or drug concentrations in the liquid which is retained in the cartridge.

In an embodiment, the first drug delivery device and the second drug delivery device comprise the same or equivalent outer dimensions and/or outer shape.“Equivalent outer dimensions” may mean that the length, the maximum outer diameter, the minimum outer diameter, and/or the outer diameter at corresponding axial and/or angular positions, of the first and the second device do not deviate significantly from one another, e.g. by 5% or less, or 2% or less. The same outer dimension may mean that the quantities specified above are equal. Furthermore, “equivalent outer dimensions” may mean that as seen along an axial direction from a proximal end of the device to a distal end, the changes in the outer diameter of the two devices occur at the same or equivalent axial positions. This may hold for cartridges of different dimensions as well as for cartridges of the same dimensions.

In an embodiment, the first tracking member path and the second tracking member path are different, e.g. of a different length. Helical first and second tracking member paths may have different pitches and/or leads or the same pitch and/or lead. Specifically, the first tracking member path may be longer than the second tracking member path and/or of a smaller pitch and/or lead. As the length of the tracking member path may be associated with the amount of drug, the maximum number of doses, and/or the number of international units contained in the cartridge and the first cartridge may contain more drug, more doses or more units than the second cartridge, the first tracking member path is expediently longer than the second one. If the lengths are different but the pitch and/or lead is maintained, the mould for the member which comprises the tracking member path need not be completely re-designed but only the length of the tool feature defining the path has to be varied.

In an embodiment, the housing comprises a plurality of housing parts. The housing parts may be assembled to one another. Preferably the housing parts are assembled so as to be non-rotatable and/or non-axially displaceable relative to each other. Both housing parts may define a section of the outer contour of the drug delivery device. Both housing parts may be visible from the exterior of the device at least partly. One of the parts may be fully visible and one only partly. The one which is visible only partly may be partially arranged in the other housing part, e.g. as an inner body.

In the two drug delivery devices discussed above, one of the second housing parts, i.e. one of the plurality of parts of the housing of the second device, and one of the first housing parts, i.e. one of the plurality of parts of the housing of the first device, may be interchangeable. That is to say, both parts may be used in an interchangeable fashion in both devices. Another one of the second housing parts and another one of the first housing parts may be non-interchangeable. The housing parts, which are non-interchangeable, may be used to interact with one or more non-interchangeable mechanism members of the dose setting and drive mechanism of the respective device. These parts expediently engage with the associated piston rod. Also, further modifications may be provided on the non-interchangeable housing part, which may

accommodate additional parts or provide space for them such as a cartridge bias system as will be discussed further below. The non-interchangeable housing part is expediently at least partially covered by the other housing part.

In an embodiment, the drug delivery device comprises a cartridge bias system. The cartridge bias system may comprise at least one resilient member. The cartridge bias system is preferably configured to exert a force on the cartridge to maintain the cartridge in a defined position, expediently relative to the mechanism unit and/or the housing. The force may be provided by the at least one resilient member. The force may act in the distal direction. The defined position may be a defined position relative to the cartridge holder. The force may be an elastic restoring force resulting from a deformation of the resilient member.

In the two drug delivery devices, the first cartridge bias system, i.e. the one of the first drug delivery device, comprises a rigid body, e.g. a rigid force transfer body. The rigid body may form a spacer to compensate the difference in dimension between the first cartridge and the second cartridge. The rigid body may be a non-interchangeable part, and, consequently, cannot be applied in the second drug delivery device. The at least one first resilient member and the at least one second resilient member of the first and second cartridge bias system may be interchangeable parts. Thus, the first resilient member may be usable in the second device and the second resilient member may be usable in the first device.

In an embodiment, the cartridge bias system of the drug delivery device may comprise a further resilient member. The further resilient member may be a non-interchangeable part or an interchangeable part.

In an embodiment, the first drug delivery device and the second drug delivery device have a first number of parts and a second number of parts, respectively. The first drug delivery device may have a greater number of parts than the second drug delivery device. The difference in part count between the two devices may be less than or equal to one of the following values: 5, 4, 3, 2, 1. For example, the first drug delivery device may comprise the rigid body in the first cartridge bias system in addition to the parts of the second drug delivery device. Otherwise, the part count may be the same.

In an embodiment, the first mechanism unit, the first cartridge unit, the second mechanism unit and/or the second cartridge unit are adjusted to one another such that the first cartridge unit cannot be connected to the second mechanism unit and/or the second cartridge unit cannot be connected to the first mechanism unit. Accordingly, although the cartridge unit may be releasable connected to the housing it can be avoided that cartridge units associated with one of the mechanism units can be connected to another mechanism unit. In this way, account can be taken for different drugs or for drug formulations contained in the liquids and/or of different filling levels. This increases user safety significantly, as dispensing drug with a wrong drive mechanism does have potentially lethal consequences. The risks can be reduced, if it is prevented that one cartridge unit is connected to another mechanism unit as it was intended for. Thus, the first mechanism unit and the first cartridge unit may be coded to one another as may the second mechanism unit and the second cartridge unit. The codings, e.g. mechanical codings, may be configured to prevent cross-connection or crosswise use of elements of different drug delivery devices.

In an embodiment, the housing of the drug delivery device may have a housing guide feature and the cartridge unit of the device may have a cartridge guide feature. The guide features may be configured to cooperate to form a guiding interface to guide movement of the cartridge unit relative to the housing to a relative position, where the housing and the cartridge unit are connected to one another. The guiding interface may guide this movement while the cartridge unit is being connected to the housing.

The first housing and the second cartridge unit may have matching guide features. That is to say, the housing guide feature of the first housing and the cartridge unit guide feature of the second cartridge unit may be adapted to form a guiding interface, which theoretically guide movement of the second cartridge unit relative to the first housing to a relative position, where the first housing and the second cartridge unit are connected. Alternatively or additionally the above applies for the second housing and the first cartridge unit. However, even though the respective guide features are adjusted such that units from different drug delivery devices could be connected to one another, it is expedient that this connection is prevented, as explained above.

In an embodiment, the second cartridge unit, which may have the longer cartridge, and the first housing are adjusted such that the second cartridge abuts the first housing and/or the rigid body of the first cartridge bias system to prevent connection of the second cartridge unit to first housing. Accordingly, before the connection position, where the second cartridge unit and the first housing were connected is reached, the cartridge abuts the first housing or the body which, preferably prevents further movement of the second cartridge unit relative to the first housing. The surface of the first housing which the second cartridge, e.g. the bung of the second cartridge, abuts may be a surface of the non-interchangeable housing part. Thus, a surface of the second cartridge may be used for coding purposes.

In an embodiment, the first cartridge holder has a first cartridge coding structure and the second mechanism unit has a second mechanism coding structure. The respective structure may comprise one or more coding features. The coding structures may be adjusted to prevent, e.g. by abutment of coding features of the mechanism unit and the cartridge holder, connection of the first cartridge holder to the second mechanism unit or the second housing. The coding structures may be configured to prevent, e.g. by abutment of coding features, relative movement of the first cartridge holder towards the second housing, particularly before the first cartridge unit is connected to the second housing. That is to say, the cartridge unit with the potentially shorter cartridge may have a coding structure to prevent connection to the second housing. In the second cartridge unit with respect to the first housing, the cartridge may be utilized to provide the coding feature, which prevents that the second cartridge and the first housing are connected. Alternatively or additionally, the second cartridge holder may have a second cartridge coding structure. The second cartridge coding structure may be compatible with the second mechanism coding structure and be incompatible with the first mechanism coding structure to prevent connection of the second cartridge unit to the first housing.

In an embodiment the (respective) cartridge coding structure is integrated into a proximally facing surface of the cartridge holder, e.g. into a proximal rim of the cartridge holder. The structure may have protruding portions and/or ramp surfaces, which are circumferentially

disposed on the cartridge holder. The protruding portions may be oriented in the proximal direction. The protruding portions may form coding features.

In an embodiment, the cartridge unit guide features and the cartridge coding structure are axially offset, e.g. by a distance greater than or equal to a distance required for an axial movement to connect the cartridge unit to the housing while the guiding interface is established.

In an embodiment, the first cartridge holder has three or more axially extending cartridge support features. The cartridge support features may define a cartridge retaining space between them. The cartridge retaining space may have a diameter greater than or equal to the one of the first cartridge. Accordingly, the first cartridge may be received within the cartridge retaining space. The cartridge retaining space may have a diameter less than the one of the second cartridge. Accordingly, the second cartridge may abut the cartridge retaining feature before it can be received entirely in the first cartridge holder. In this way, it is avoided that the wrong cartridge is assembled within the first cartridge holder. Likewise, a radial position is stabilized of the first cartridge. Thus, the cartridge support features may bridge a void, which is present within the interior of the first cartridge holder, which may have the same or substantially the same outer dimensions as the second cartridge holder. Accordingly, the cartridge support features may distinguish the first cartridge holder from the second cartridge holder.

In an embodiment, the first cartridge holder and the second cartridge holder both have a length, which is greater than the length of the first cartridge and the one of the second cartridge.

Accordingly, the respective cartridge can be received entirely in the associated cartridge holder.

In an embodiment, when the cartridge holder is connected to the housing, a portion of the cartridge holder protrudes, e.g. distally, from the housing. The length of the first portion of the first cartridge holder which protrudes from the first housing and the second portion of the second cartridge holder which protrudes from the second housing may be identical or substantially identical, e.g. with a deviation of 5% or less or 2% or less.

In an embodiment, the first cartridge holder and the second cartridge holder may have identical outer contours or shapes.

In an embodiment, the first cartridge holder and the second cartridge holder may have the same or equivalent outer dimensions and/or outer shape. Equivalent may have the meaning defined further above.

In an embodiment, the drug delivery device comprises a cap. The cap of the first drug delivery device and the one of the second drug delivery device may be interchangeable parts or non-interchangeable parts. The cap may designed to be connected to the housing or the cartridge holder. The cap, when connected, preferably covers at least the majority of the length of the cartridge holder or the entire cartridge holder.

In an embodiment, the second piston rod has one or more blocking features, which are arranged to block movement of the second piston rod in the distal direction relative to the first cartridge body. The respective blocking feature may protrude radially from the second piston rod. A distally facing surface of the blocking feature of the second piston rod may be arranged to abut a proximally facing surface of the first cartridge, e.g. the proximal rim of the first cartridge or cartridge body. The blocking feature may define a radial extension or diameter of the piston rod in the region of the blocking feature, which is less than the inner diameter of a proximal opening of the second cartridge or cartridge body and/or greater than or equal to the inner diameter of a proximal opening of the first cartridge or cartridge body. Thus, if accidentally, a first cartridge unit is attempted to be assembled to a second mechanism unit, for example if no coding is provided or the coding is destroyed, it is still prevented that the second piston rod can displace the first bung distally relative to the first cartridge body as the blocking feature abuts the cartridge or cartridge body. Accordingly, user safety is increased by this measure. The blocking feature may be offset axially from a distal end of the second piston rod. The distance by which the blocking feature is offset is preferably small, e.g. less than the distance by which the second piston rod is moved during the dose delivery operation, if the minimum settable dose is set by the second dose setting and drive mechanism. Thus, the delivery operation can be stopped timely by the blocking feature abutting the cartridge, for every dose which can be set.

In an embodiment, as seen from the distal end along the axis of the second piston rod, the second bung interface member connected to the second piston rod has a radial extension or diameter greater than the one of the second piston rod in the region of the blocking feature. The second bung interface member may be dimensioned so as not to fit into the interior of the first cartridge body, i.e. it may be a non-interchangeable mechanism member. The bung interface member may be accessible for manipulation by the user when the cartridge unit has been disconnected from the housing. Thus the user could theoretically remove the second bung interface member from the second piston rod and use the second piston rod to drive the first bung distally. This may be prevented by the blocking feature(s).

In an embodiment, the force transfer chain or coupling sequence in the dose setting and drive mechanism from the user interface member or dose setting member to the piston rod when the

member is manipulated by the user is the same for the first dose setting and drive mechanism and for the second dose setting and drive mechanism, expediently during the dose delivery operation and/or the dose setting operation. Thus, the couplings in the mechanisms may be equal, equally acting, and/or the same couplings may be present between the same types of members. The couplings may comprise splined or rotationally locked couplings, helical, e.g. threaded, couplings and/or axial couplings such as axial locks between members. Accordingly, the components of the two different dose setting and drive mechanisms may move relative to one another in a corresponding way as seen from the user interface during dose setting and dose delivery. Nevertheless, the same dose setting operation, e.g. by rotation and/or axial displacement of the user interface member or dose setting member by the same angle or axial distance preferably results in a different axial displacement of the piston rod during dose delivery for the first dose setting and drive mechanism and the second dose setting and drive mechanism.

In an embodiment, during the dose setting operation, relative movement between the mechanism members of the drug delivery devices is governed by a dose setting coupling system where a load is propagated from the user interface member through the mechanism members in a dose setting load transfer sequence. The first dose setting coupling system and the second dose setting coupling system may have the same load transfer sequences. They may have the same types of relative movement (axial, rotational, or helical) and also the same absolute relative displacements (angle and/or axial distance) between the components or member, expediently of corresponding types, which move relative to another during the dose setting operation.

In an embodiment, during the dose delivery operation, relative movement between the mechanism members is governed by a dose delivery coupling system, where a load is propagated from the user interface member through the mechanism members in a dose delivery load transfer sequence. The dose delivery coupling system may differ from the dose setting coupling system, e.g. on account of the coupling provided by the clutch member being released. This load may be transferred to the bung or the bung interface member by the piston rod. For the first and the second drug delivery device, the first dose delivery coupling system may have the same load transfer sequences. Also, the couplings between equal types of members may be equal in or along the load transfer sequence. However, the couplings may generate different relative displacements between the components during dose delivery.

In an embodiment, the device may be a manually operated device. Thus, the entire dispensing force may be provided by a user. Alternatively, the device may be a spring-assisted device, where only a part of the force is provided by the user and the remaining part is provided by a spring. As a further alternative, the device may be a spring-driven device, where the entire dispensing force is provided by the spring.

In an embodiment, in one of the drug delivery devices, for example in the first drug delivery device which may have the cartridge of reduced length and/or diameter, the piston rod may be moved proximally, i.e. away from the bung, in the dose setting operation. Moving the piston rod away from the bung may reduce the risk of‘weeping’ of drug from the cartridge during dose setting. The distance by which the piston rod is moved in the dose setting operation may be greater than a distance by which the piston rod in the other drug delivery device of the two drug delivery devices, e.g. the second device, moves in the proximal direction during dose setting. Particularly, in the other drug delivery device, movement in the proximal direction of the piston rod during dose setting may be avoided. Thus, the bung interface member or the piston rod may be consistently in contact with the bung in the other device. The distance by which the piston rod is moved proximally relative to the bung during dose setting may be less than or equal to one of the following values: 1 mm, 0.5 mm, 0.3 mm, 0.2 mm, 0.1 mm. The distance by which the piston rod is moved proximally may depend on the size of the dose which is set. The values may relate to the distance by which the piston rod is moved if, during the dose setting operation the maximum settable dose which can be delivered by the drug delivery device is set. The distance by which the piston rod is moved proximally may be insignificant as compared to the movement of the other mechanism members during dose setting.

The distance (D) by which the piston rod is moved proximally for the maximum settable dose multiplied by the mechanical advantage (MA) of the dose setting and drive mechanism, which may be greater than 1 , is preferably less than or equal to the relative axial displacement (AD), e.g. in the distal direction, between members which are coupled by a clutch member, e.g. the dosing clutch member, said axial displacement being required to release the coupling provided by the clutch member, for example in order to switch from the dose setting operation to the dose delivery operation. For example, D*MA may be less than or equal to one of the following value: 0.5AD, 0.3AD, 0.2AD. The movement for releasing the coupling may be necessary anyway and the user may not even notice that there is an additional movement which he has to perform before the piston rod contacts the bung again and drug is actually dispensed during dose delivery. The proximal movement of the piston rod during dose setting should, of course, preferably be less than the distal movement of the piston rod required to deliver the set dose or maximum settable dose, e.g. less than 10%, less than 5%, or less than 2%.

The difference between the two devices in the proximal movements of the piston rod during dose setting may originate from an interchangeable member, e.g. the dose indication member, which is used in both devices, where said member is, however, mismatched somewhat to the remaining mechanism members in one device, expediently the one where the piston rod moves proximally during dough setting. Such a slight mismatch may be still tolerable, on account of the benefits of an interchangeable member, e.g. regarding cost efficiency.

In one device, two different threaded couplings, e.g. couplings between two different pairs of members or parts, may be governed or formed by threads, e.g. helical threads, of the same pitch and/or lead. One coupling may be between the drive member and the piston rod. The other coupling may be between the dose indication member and the housing. In the other drug delivery device, e.g. the first drug delivery device, the couplings may still be threaded couplings between corresponding members or types of members. However, the leads and/or pitches of the threads may be different, preferably by less than 5%, less than 2%, or less than 1%. Such a slight mismatch may result in a proximal movement of the piston rod during dose setting in one of the devices as discussed above.

Another aspect relates to a method of producing a first mechanism unit which is configured to be connected to a first cartridge unit to form first a drug delivery device, comprising the following steps:

- providing a second mechanism unit as a model for the first mechanism unit, the second mechanism unit being configured to be connected to a second cartridge unit which is different from the first cartridge unit, wherein the second mechanism unit comprises a second housing and a second dose setting and drive mechanism which is at least partly arranged in the second housing, the second dose setting and drive mechanism comprising a plurality of second mechanism members which are movable relative to the second housing and/or relative to one another during a dose setting operation for setting a dose of the second liquid and/or a dose delivery operation for delivering the set dose,

- providing a first housing for the first mechanism unit;

- producing one interchangeable mechanism member in accordance with one of the second mechanism members;

- producing one non-interchangeable mechanism member which is adjusted to the first cartridge unit,

- assembling a first dose setting and drive mechanism for the first mechanism unit, the first dose setting and drive mechanism comprising the interchangeable mechanism member, which expediently could be used in the second dose setting an drive mechanism, and the non-interchangeable mechanism member, which expediently cannot be used in the second dose

setting and drive mechanism, and arranging the interchangeable mechanism member and the non-interchangeable mechanism member in the first housing, e.g. during or after the first dose setting and drive mechanism has been assembled.

With the proposed concepts, drug delivery devices can be adjusted to specific drugs or different drug concentrations, filling levels in cartridges, and/or cartridge dimensions. Although the drugs and drug concentrations may be different, the same dose setting movements, that is to say the same rotation angles and/or axial displacements of members, which are manipulated by the users, such as the dose indication member, the dose setting member and/or the user interface member, occur. However, the resulting axial displacement of the piston rod relative to the housing and/or the cartridge body may be different. This has various advantages. For example, the moulds or assembling tools for the interchangeable parts can be reused. Only a few parts of the mechanism need adjustment, which then are non-interchangeable parts. As the general mechanism of an existing device may have a proven functionality already, slightly readjusting an existing device may provide a regulatory advantage. Thus, approval by the regulatory authorities like the FDA, for example, may be more easily gained for a device architecture which has a proven record already, where this architecture is slightly modified.

The terms "distal" and "proximal" as used herein may refer to opposite axial directions or ends. "Distal" may refer to a direction towards the dispensing end or an end of a component of a drug delivery device which is or is to be arranged closest to the dispensing end of the cartridge, the cartridge unit or the drug delivery device. "Proximal" may refer to a direction away from the dispensing end or an end which is or is to be arranged further away from the dispensing end.

Features disclosed above in conjunction with the drug delivery device should not be regarded as referring to only the recited aspect or embodiment. Rather, the features also apply for other embodiments or aspects. Features disclosed in conjunction with the device do also apply for the method, for example, and vice versa. Of course, features disclosed in specific embodiments, be it above or further below, can also be applied in combination with one another and/or with other features of other aspects or embodiments. Features disclosed for the arrangement with two drug delivery devices may, of course, also apply for one drug delivery device and vice versa.

Further features, advantages and advantageous embodiments of the present disclosure will become apparent from the following description of the exemplary embodiments in conjunction with the drawings.

Figure 1 shows a drug delivery device with a cap attached.

Figure 2 shows the drug delivery device of Figure 1 with the cap removed and a dose of 79 units dialed.

Figure 3 shows in an exploded view the components of the drug delivery device of Figure 1. Figure 4 shows the outer body of the drug delivery device of Figure 1.

Figure 5a shows the inner body of the drug delivery device of Figure 1.

Figure 5b shows a detail of the inner body of Figure 5a.

Figure 6 shows the cartridge holder of the drug delivery device of Figure 1.

Figure 7a shows a first display member component of the drug delivery device of Figure 1. Figure 7b shows a detail of the first display member of Figure 7a.

Figure 8 shows a second display member component of the drug delivery device of Figure 1. Figure 9 shows a first driver component of the drug delivery device of Figure 1.

Figure 10 shows a second driver component of the drug delivery device of Figure 1.

Figure 1 1 shows a third driver component of the drug delivery device of Figure 1.

Figure 12 shows the last dose nut of the drug delivery device of Figure 1.

Figure 13 shows a clutch component of the drug delivery device of Figure 1.

Figure 14 shows a first clicker component of the drug delivery device of Figure 1.

Figure 15 shows a second clicker component of the drug delivery device of Figure 1.

Figure 16 shows the button of the drug delivery device of Figure 1.

Figure 17 shows a cut-away view of the proximal part of the drug delivery device of Figure 1 in a zero unit position with the button released.

Figure 18 shows a cut-away view of the proximal part of the drug delivery device of Figure 1 in a position with some units dialed.

Figure 19 shows a cut-away view of the proximal part of the drug delivery device of Figure 1 in a zero unit position with the button pressed.

Figures 20A through 21 B schematically illustrate embodiments of cartridge assemblies where a cartridge is assembled to a cartridge holder.

Figure 22 shows a schematic sectional view of a section or region of a drug delivery device.

Figure 23 shows on the basis of a schematic perspective view an embodiment of a cartridge bias system employed in the device.

Figure 24 shows a component of the cartridge bias system, a rigid force transfer body, on the basis of a perspective view.

Figure 25 shows a part of a section of Figure 22 with highlighted areas.

Figure 26 illustrates a perspective view of a housing part or housing of the device.

Figure 27 illustrates a sectional view of the housing or housing part.

Figure 28A and 28B illustrate an assembling process, where a rigid force transfer body is assembled to a housing part or housing, where Figure 28A shows the unassembled state and Figure 28B shows the assembled state.

Figure 29 shows a schematic sectional view through an embodiment of a housing part.

Figure 30 shows a perspective view of an embodiment of the rigid force transfer body.

Figures 31 and 32 show different perspective views of the housing part of Figure 29.

Figure 33A illustrates the force transfer body before it is mounted to the housing part and Figure 33B illustrates the situation after the body has been mounted.

Figure 34 shows a perspective view of a force transfer body to which one resilient member is assembled.

Figure 35 shows a schematic sectional view of a section or region of an embodiment of a drug delivery device.

Figures 36A and 36B show a body structure on the basis of a perspective view, in a deformed state in Figure 36B and an undeformed state in Figure 36A.

Figure 37 shows a schematic sectional view through an embodiment of a drug delivery device.

Figures 38A through 38C illustrate modifications to a piston rod.

Figures 39A and 39B illustrate modifications to a bearing.

Figures 40A and 40B illustrate modifications to a drive member part.

Figures 41 A and 41 B illustrate modifications to a tracking member.

Figures 42A and 42B illustrate modifications in a housing part.

Figure 43 illustrates an embodiment of a piston rod on the basis of different sectional representations.

Figures 44 through 50 illustrate embodiments of coding systems or structures.

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.

Figures 1 and 2 show a drug delivery device 1 in the form of an injection pen. The device has a distal end (lower end in Figure 1 ) and a proximal end (upper end in Figure 1 ). The component parts of the drug delivery device 1 are shown in Figure 3 in more detail. The drug delivery

device 1 comprises an outer housing part 10, an inner body 20, a piston rod 30, a driver or drive member 40, a nut or tracking member 50, a display mechanism 60, a button or user interface member 70, a cartridge holder 80 for receiving a cartridge 81 , a clutch 90, a clicker 100, a spring or a plurality of springs 110, a cap 120 and a window insert 230. A needle arrangement (not shown) comprising a needle hub and a needle cover may be provided as additional components, which can be exchanged as explained above. The piston rod 30 comprises a bearing 31. The driver 40 comprises a distal driver part 41 and a proximal driver part 42. The parts 41 and 42 are coupled by a coupler 43. The display mechanism 60 or the drug delivery device comprises a number sleeve or dose indicator 61 and a dial sleeve or dose setting member 62. The clicker 100 comprises a distal clicker part 101 , a proximal clicker part 102 and a spring 103.

The outer housing part 10, which is shown in Figure 4, is a generally tubular element having a distal part 11 for attaching the inner body 20 and a proximal part, which is provided with a rotational hard stop 12 on its inner surface (not shown) which contacts one or more mating faces of the display mechanism 60 when the maximum units (in this example 80U, e.g. 80IU) stop is engaged. A proximal end face of the housing part also serves as the end of dose dispense stop for the button 70, and the bore in the end face centers the display mechanism 60 during both dialing and dispense. An aperture 13 is provided for receiving window insert 230. The outer body 10 provides the user with a surface to grip and react against during dispense.

The inner body 20 is a generally tubular element having different diameter regions. As can be seen in Figures 17 to 19, the inner body 20 is received in the outer body 10 and permanently fixed therein to prevent any relative movement of the inner body 20 with respect to the outer body or housing part 10. The inner body has the functions to house the drive mechanism within, guiding the clickers and the last dose nut 50 via internal splines, to provide an internal thread through which the piston rod 30 (lead screw) is driven, to support and guide the number sleeve 61 and the dial sleeve 62 on an external thread form, to secure the cartridge holder 80 and to secure the outer body 10 and the window insert 230. Thus, the inner body interacts with components of the dose setting and drive mechanism. The inner body and the outer housing part may together form a housing of the device 1.

The outermost diameter of the inner body 20 also forms part of the visual design and remains visible when the cap 120 is secured to the cartridge holder 80 as a ring separating the cap 120 from the outer body 10. This visible ring also has depressions which align with the cap snap features on the cartridge holder 80 to indicate that the cartridge holder has been correctly fitted.

An external thread 21 is provided on the outer surface of the inner body 20. Further, splines 22 (Figure 5b) are provided on the inner surface of the inner body 20. These internal splines 22 guide the clicker 100 axially during both dialing/setting and dispense and also prevent the last dose nut 50 from rotating. Some of the splines may be wider to ensure correct rotational assembly of the internal components, and these wider splines may have a stepped entry and angled surface to encourage the last dose nut 50 to rotate up against the stop face on the distal drive sleeve 41 during assembly. At the open end shown in Figure 5b there are additional short splines which together with the alternating long splines 22 are used to rotationally lock the button 70 (dose dial grip) at the end of dispense and serve to increase the strength of the 0U dial stop when the button 70 is depressed. This is achieved by engagement with male spline features on the clutch component 90.

Bayonet features 23 guide the cartridge holder 80 into the mechanism, e.g. during cartridge replacement, compressing the cartridge bias spring 1 10, and then back off the cartridge holder 80 a small distance in order to reduce axial play in the mechanism. Snap features inside the inner body 20 lock the cartridge holder 80 rotationally when it has been correctly fitted. The profile of these snaps aims to prevent the user from partially fitting the cartridge holder 80, the cartridge bias spring 1 10 ejecting the cartridge holder 80 if the snaps have not at least started to engage. A window retention nose 24 retains the window insert 230 when the outer body 10 and window insert 230 assembly is axially inserted onto the inner body 20. Two diametrically opposite stop faces 25 define the rotational end position for the number sleeve 61. This end position may be the end of dose detent position (e.g. corresponding to a zero dose being set, e.g. of 0U, such as 0IU).

The piston rod 30 is an elongate element having two external threads 32, 33 with opposite hand which overlap each other. One of these threads 32 engages the inner thread of the inner body 20. A disk-like bearing 31 is provided at the distal end of the piston rod 30. The bearing 31 may be a separate component as shown in Figure 3 or may be attached to the piston rod 30 as a one-piece component via a predetermined breaking point.

The piston rod 30 transfers the dispense load from the driver 40 to the bearing 31 , creating a mechanical advantage greater than 1 : 1 by converting the torque generated on the piston rod 30 by the driver 40 thread interface into additional axial load as the piston rod passes through the thread in the inner body 20. The piston rod 30 is reset by pressing on the bearing 31 and this in turn rotates the piston rod back into the inner body 20. This disengages and then rotates the distal drive sleeve 41 , thereby resetting the last dose nut 50 back to its starting position on the distal drive sleeve 41.

The driver 40 is a generally tubular element having in the embodiment shown in the Figures a plurality of components which are depicted in Figures 9 to 11 in more detail.

The distal drive sleeve 41 engages with the piston rod thread 33 to drive the piston rod 30 through the inner body 20 during dose delivery. The distal drive sleeve 41 is also permanently connected to the coupler 43 which in turn is releasably engaged through reset clutch features to the proximal drive sleeve 42. The two halves of the drive sleeve are rotationally and axially connected during dialing and dispense, but are de-coupled rotationally during device reset so that they can rotate relative to each other.

The external thread 44 engages with the last dose nut 50. The thread form has three stages, a shallow first stage (left hand side in Figure 9) over which the nut 50 travels to count the majority of the units dialed, a fast stage over which the last dose nut moves rapidly axially prior to engaging the stop faces, and a final shallow section which ensures that when the stop faces have engaged, the axial restraint on the nut 50 extends over a reasonable length of thread form. Four equi-spaced stop faces 45 engage with mating stop faces 51 on the last dose nut 50 to limit the number of units that can be dialed. Splines 46 are provided at the proximal end of distal drive sleeve 41 to transfer torque from or to the coupler 43, which may be snapped on the distal drive sleeve 41.

The proximal drive sleeve 42 shown in Figure 10 supports the clicker components 100 and the clutch 90 and transfers rotational movement from the dose button 70 to the coupler 42 and distal drive sleeve 41.

Teeth features 47 located at the distal end of proximal drive sleeve 42 engage with the reset clutch features on the coupler 43 to connect both halves of the drive sleeve during dialing and dispense. During reset these teeth 47 disengage.

Several splines are provided on the outer surface of proximal drive sleeve 42 engaging with the distal and/or proximal clicker part 101 ,102, preventing relative rotation during dialing and dispense. Further splines, which are located in the middle region of proximal drive sleeve 42, engage with the clutch 90 component. They may be arranged to be non-rotationally symmetric so that the various clicker components cannot be assembled accidentally upside down.

The proximal portion of proximal drive sleeve 42 has four arms or fingers 48. A hook-like bearing surface 49 exists on the underside (as seen in Figure 10) of flange segments on the

end of the flexible fingers 48. The flexible fingers 48 are separated with gaps or slots that make space for the button 70 to snap to the clutch 90 and also enable these fingers to flex inwards during assembly of the proximal drive sleeve 42 to the dial sleeve 62. After assembly the hooks 49 retain the proximal drive sleeve 42 relative to the dial sleeve 62 under the reaction force from the spring 103. During dispense the button 70 depresses the spring 103 via the clutch 90 and the clicker components and this spring 103 is reacted through the coupler 43 to the proximal drive sleeve 42 which then through these bearing surfaces applies axial load to the dial sleeve 62. This axial load drives the dial sleeve 62 and hence number sleeve 61 along the helical thread of the inner body 20, back into the body of the device, until the 0U stop faces on the number sleeve 61 contact the inner body 20.

The coupler 43 shown in Figure 1 1 rotationally couples the two halves of the drive sleeve together during dialing and dispense, whilst allowing them to de-couple during reset. The coupler 43 also has to transfer the last dose protection stop load from the proximal drive sleeve 42 to the distal drive sleeve 41. Two sets of teeth are provided in the coupler 43 for engaging teeth 46 and teeth 47, respectively. The coupler 43 is snapped onto distal drive sleeve 41 allowing limited relative axial movement with respect to the proximal drive sleeve 42.

The nut 50 is provided between the inner body 20 and the distal drive sleeve 41 of driver 40. Stop faces 51 are located on the proximal face of last dose nut 50 to limit the number of units that can be dialed if the stop faces 51 contact stops 45 of distal drive sleeve 41. The function of the last dose nut 50 is to prevent the user from dialing beyond a finite amount. This limit is based on the dispensable volume of the cartridge 81 and when reached, the user must replace the cartridge 81 and reset the device.

External ribs 52 of the nut 50 engage splines 22 of inner body 20. An internal thread 53 of the nut engages the external thread 44 of distal drive sleeve 41. As an alternative, splines and ribs could be provided on the interface between the nut 50 and the driver 40 and threads could be provided on the interface between the nut 50 and the inner body 20. As a further alternative, the nut 50 may be designed as e.g. a half nut.

The display mechanism or display member 60 is a generally tubular element or system which is composed of number sleeve or dose indicator 61 and dial sleeve 62 which may be snapped together during assembly to axially and rotationally constrain these two components, which may thus act as a single part or member. However, other device architectures may involve a dose setting member or dial sleeve 62 which moves axially and/or rotationally relative to the dose indicator or number sleeve 61 during dose setting and/or dose delivery. For example, the dose setting member may be manipulated by a user for setting a dose and the button may only be operated when dispensing the set dose. In the present embodiment, however, the button 70 is manipulated for setting and dispense.

The main functions of the number sleeve 61 depicted in Figure 8 are to provide a surface onto which dose numbers can be printed to display the dialed dose, to guide the helical path of the internal mechanism during dialing to follow the helical thread form on the piston rod 30 when threaded to the inner body 20 and to attach to the dial sleeve 62.

The number sleeve 61 is designed to be fully enclosed in the outer body 10 during dialing and dispense and therefore only the dialed dose is visible to the user through the window aperture. The number sleeve has a 0U (minimum or zero dose) stop face 63 to limit its travel when dialed in but the 80U (maximum dose) stop faces that limit the dialed out condition are located on the dial sleeve 62. At the end of each dispense stroke, this stop face 63 engages with mating surface 25 on the inner body 20 to limit the rotational position of the number sleeve 61.

A helical drive face 64 forms a thread that guides the number sleeve 61 during dialing and dispense to follow the helical path 21 on the inner body.

The dial sleeve 62 is assembled to the number sleeve 61 such that once assembled, no relative movement is allowed. The parts are made as separate components to enable both molding and assembly. Also, whereas the number sleeve 61 is preferably white to give contrast for the e.g. black dose numbers, the dial sleeve 62 color can be chosen to suit the aesthetics or perhaps to distinguish the drug type, if desired.

At the dose proximal end, the dial sleeve 62 has internal clutch features 65 that engage with the clutch component 90 during dialing and disengage from the clutch during dispense. These clutch features 65 rotationally lock the dial sleeve 62 to the clutch 90 during dialing and when the 0U and 80U stops are engaged. When the button 70 is depressed these clutch features disengage to allow the clutch 90 and drive mechanism to move axially whilst the dial sleeve 62 and number sleeve 61 spin back to the 0U start position.

The dial sleeve 62 rotates out during dialing through its engagement with the clutch 90 and number sleeve 61 , and rotates back in during dispense under the axial force applied by the proximal drive sleeve 42 to a flange-like bearing face 66 on the end of the dial sleeve. This bearing face 66 engages with the flexible arms 48 of the proximal drive sleeve 42 during

dispense. Two diametrically opposite faces 67 engage with the outer body 10 when the maximum dose (e.g. 80U) has been dialed, forming the maximum dose stop faces.

A ratchet arm 68 engages with ratchet features on the button 70 (dose dial grip) to provide audible feedback during dispense, giving one click per unit delivered. Further, this prevents the user from gripping and rotating the number sleeve 61 outwards from a partially dialed out position whilst holding the button 70 pressed in. This would back wind the piston rod 30 which would result in an under dose on the subsequent dialed dose. It may further strengthen the 0U stop.

The button 70 which is shown in Figure 16 serves as a dose dial grip and is retained by the clutch 90 to transfer the actions of the user to the clutch. It also carries ratchet teeth 71 that engage the ratchet arm 68 on the dial sleeve 62, which serves as the dispensing clicker giving audible feedback (ratchet clicks), and an end face 72 which serves as the dose completion stop face with the outer body 10. This end face 72 thus serves to define the end position during dispense when it contacts the outer body 10 to provide a very positive stop improving dose accuracy.

A central sleeve-like portion of button 70 is provided with four arms 73 having hook-like snap features 74 at their respective distal ends. The arms 73 form splined surfaces engaging with the clutch 90 to transfer torque from the button 70 through the clutch to the dial sleeve 62 and proximal drive sleeve 42. The snap features 74 engage apertures in the clutch 90 and are designed with angled undercut faces to maintain engagement when an axial load is applied to pull the button 70 out of the pen body 10. The space between arms 73 defines pockets giving clearance for the flexible arms 48 of proximal drive sleeve 42 to slide freely relative to the button 70 and clutch 90 when the button 70 is depressed and released during dose dispense.

The cartridge holder 80 attaches to the inner body 20 with a bayonet connection 82 and houses the glass ampoule or cartridge 81 containing the medication to be dispensed. The cartridge holder 80 includes an aperture 83 in the rear face (as seen in Figure 6) which if gripped by the user prevents the ampoule from falling out when the cartridge holder is removed from the inner body 20. The front face is printed with a dose number scale. The threaded distal end 84 is used to attach disposable pen needles.

A tubular clutch 90 is provided between the display mechanism or member 60 and the button 70. The clutch is fixed relative to and retains the button 70 and together they travel axially relative to the proximal drive sleeve 42 when the button 70 is depressed during dispense, disengaging the

clutch teeth from the dial sleeve 62. It also transfers torque from the button to the proximal drive sleeve 42, and the dialing and 0U/80U stop loads from the button via the clutch teeth to the dial sleeve and number sleeve.

Drive sleeve splines 91 provided on an inner surface of the clutch engage with the proximal drive sleeve 42. At the distal end face, clutch biasing teeth 92 are provided which mate with similar teeth on the proximal clicker part 102 to ensure that in the button out position (dialed dose) the clutch is locked in rotation to the proximal clicker part 102 under the biasing action of the clutch spring 103. The teeth 92 are shallow in height to prevent the proximal clicker part 102 from engaging with splines on the proximal drive sleeve 42 during dialing. Four snap apertures 93 serve to retain the snap features 74 of button 70. Near its proximal end, the clutch has splines 94 which at the end of dispense with the button 70 depressed lock to the inner body 20 to prevent the user from rotating the button 70 below the 0U position.

Clutch teeth 95 engage with clutch teeth 65 of the dial sleeve to rotationally couple the button 70 via the clutch to the number sleeve 61. During dispense the clutch is moved axially so as to disengage these clutch teeth 95 releasing the dial sleeve 62 to rotate back into the device whilst the clutch 90 and hence driver 40 move axially to dispense the dose.

The clicker 100 comprises a distal clicker part 101 , a proximal clicker part 102 and a spring 103. The clutch spring 103 serves to bias the button 70 out so that at the end of a dose the button 70 pops out, re-engaging the clutch 90 with the dial sleeve 62 ready for dialing. Further, it provides the spring force for the clicker components to act as clickers and also as detent positions for the number sleeve 61. In addition, it holds the two halves of the drive sleeves 41 , 42 in rotational engagement during dialing and dispense, whilst allowing them to disengage during device reset.

The distal clicker part 101 is permanently splined to the proximal drive sleeve 42 and engages with the proximal clicker part 102 which in turn is splined to the inner body 20. During dialing when the drive sleeve is rotated relative to the inner body, the two clickers 101 , 102, rotate relative to each other under the compression force of the clutch spring 103. This force combined with the clicker teeth formed on the end face of each clicker provides the clicks and also the detent dialing positions.

During dispense the two clickers 101 , 102 are pressed together under the dispense load and therefore prevent relative rotation between the proximal drive sleeve 42 and inner body 20, driving the piston rod forwards to deliver the dose. The splines 104 on the inner bore rotationally couple the distal clicker part 101 to the proximal drive sleeve 42 at all times, but allow free axial movement when the button 70 is depressed during dispense and when the two clickers ride over each other during dialing. The profile of the clicker teeth 105, 106 on both distal clicker part 101 and proximal clicker part 102 are identical and ride over each other under the compressive load from the spring 103 during dialing.

Claims

1. An arrangement of drug delivery devices, comprising

a first drug delivery device (1 ) and a second drug delivery device (1 ), wherein

the first drug delivery device (1 ) comprises

- a first housing (10, 20, 350) having a proximal end and a distal end,

- a first cartridge unit (300) releasably or permanently connected to the first housing (10, 20, 350) or retained in the first housing,

- the first cartridge unit (300) comprising a first cartridge (301 ) containing a first liquid (307), wherein the first cartridge (301 ) comprises a first bung (360) and a first cartridge body (340), the first bung being movable in the distal direction relative to the first cartridge body (340) to dispense the first liquid from the first cartridge (301 ),

- a first dose setting and drive mechanism which is at least partly arranged in the first housing (10, 20, 350), the first dose setting and drive mechanism comprising a plurality of first mechanism members which are movable relative to the first housing (10, 20, 350) during a dose setting operation and/or a dose delivery operation, wherein

the second drug delivery device (1 ) comprises

- a second housing (10, 20, 350) having a proximal end and a distal end,

- a second cartridge unit (300) releasably or permanently connected to the second housing (10, 20, 350) or retained in the second housing,

- the second cartridge unit (300) comprising a second cartridge (301 ) containing a second liquid (307), wherein the second cartridge comprises a second bung (360) and a second cartridge body (340), the second bung being movable in the distal direction relative to the second cartridge body to dispense the second liquid from the second cartridge,

- a second dose setting and drive mechanism which is at least partly arranged in the second housing (10, 20, 350), the second dose setting and drive mechanism comprising a plurality of second mechanism members which are movable relative to the second housing (10, 20, 350) during a dose setting operation and/or a dose delivery operation, wherein the first liquid (307) and the second liquid (307) are different,

the first mechanism members and the second mechanism members each comprise at least one interchangeable mechanism member, which could be used to assemble both, the first dose setting and drive mechanism and the second dose setting and drive mechanism, and

the first mechanism members and the second mechanism members each comprise at least one non-interchangeable mechanism member, wherein

the first mechanism members comprise

- a first piston rod (30) arranged to drive movement of the first bung during the dose delivery operation,

- a first drive member (40) operatively coupled to the first piston rod (30) to transfer a driving force to the first piston rod,

- a first user interface member (70) which is operable by the user for performing the dose setting operation and/or the dose delivery operation,

- a first dose indication member (61 ) configured to indicate the size of the set dose, and

- a first dosing clutch member (90) configured to couple two first mechanism members during only one of the dose setting operation and the dose delivery operation, wherein the second mechanism members comprise

- a second piston rod (30) arranged to drive movement of the second bung (360) during the dose delivery operation,

- a second drive member (40) operatively coupled to the second piston rod (30) to transfer a driving force to the second piston rod,

- a second user interface member (70) which is operable by the user for performing the dose setting operation and/or the dose delivery operation,

- a second dose indication member (61 ) configured to indicate the size of the set dose, and

- a second dosing clutch member (90) configured to couple two second mechanism members during only one of the dose setting operation and the dose delivery operation, and wherein

the first cartridge (301 ) and the second cartridge (301 ) have different dimensions.

2. The arrangement of claim 1 , wherein the first mechanism members and the second mechanism members comprise a plurality of interchangeable mechanism members and a plurality of non-interchangeable mechanism members, wherein the number of interchangeable mechanism members is greater than the number of non-interchangeable mechanism members.

3. The arrangement of claim 1 or 2, wherein the following members are non-interchangeable mechanism members:

- the first and second piston rod (30); and

- the first and second drive member (40), and wherein

the following members are interchangeable mechanism members:

- the first and second user interface member (70);

- the first and second dose indication member (61 ); and

- the first and second dosing clutch member (90).

4. The arrangement of any one of the preceding claims, wherein the first mechanism members comprise all of the following members or types of members:

- a first bung interface member (31 ) coupled to the first piston rod and configured to abut the first bung (360);

- a first dose setting member (62) which is movable relative to the first housing (10, 20, 350) to set the size of a dose of first liquid to be delivered from the first cartridge (301 ),

- a first tracking member (50) coupleable or coupled to a first tracking member path (44), wherein the position of the first tracking member along the first tracking member path is indicative for the volume of first liquid remaining in the first cartridge (301 ) and/or having been dispensed from the first cartridge;

- a first reset clutch member (43) configured to couple two first mechanism members during the dose setting operation and the dose delivery operation,

- a first clicker member (101 , 102) provided to generate an audible and/or tactile feedback during the dose setting operation and/or the dose delivery operation,

and wherein

the second mechanism members comprise all of the following members or types of members:

- a second bung interface member (31 ) coupled to the second piston rod (30) and configured to abut the second bung (360);

- a second dose setting member (62) which is movable relative to the second housing (10, 20, 350) to set the size of a dose of second liquid (307) to be delivered from the second cartridge (301 ),

- a second tracking member (50) coupleable or coupled to a second tracking member path (44), wherein the position of the second tracking member along the second tracking member path is indicative for the volume of second liquid remaining in the second cartridge (301 ) and/or having been dispensed from the second cartridge (301 );

- a second reset clutch member (43) configured to couple two second mechanism members during the dose setting operation and the dose delivery operation,

- a second clicker member (101 , 102) provided to generate an audible and/or tactile feedback during the dose setting operation and/or the dose delivery operation.

5. The arrangement of claim 4,

wherein the following members are non-interchangeable mechanism members:

- the first and second bung interface member (31 ); and

- the first and second tracking member (50).

6. The arrangement of any one of claims 4 and 5,

wherein the following members are interchangeable mechanism members:

- the first and second reset clutch member (43); and

- the first and second clicker member (101 , 102).

7. The arrangement of any one of claims 1 to 6,

wherein the second piston rod (30) has one or more blocking features (39) which are arranged to block movement of the second piston rod (30) in the distal direction relative to the first cartridge body (340).

8. The arrangement of any one of the preceding claims,

wherein the first drug delivery device (1 ) and the second drug delivery device (1 ) have equivalent outer dimensions and/or outer shape.

9. The arrangement of any one of the preceding claims,

wherein the first cartridge body (340) is shorter than the second cartridge body (340) and has a smaller diameter than the second cartridge body, and wherein the first liquid (307) and the second liquid (307) comprise different drugs or different drug formulations.

10. The arrangement of any one of the preceding claims,

wherein the first housing (10, 20, 350) comprises a plurality of first housing parts which are assembled to one another and wherein the second housing comprises a plurality of second housing parts which are assembled to one another, wherein

one (10) of the second housing parts and one (10) of the first housing parts are interchangeable parts and another one (20, 350) of the second housing parts and another one (20, 350) of the first housing parts are non-interchangeable parts.

11. The arrangement of any one of the preceding claims,

wherein the first drug delivery device (1 ) comprises a first cartridge bias system (400) which comprises at least one first resilient member (402, 403), wherein the first cartridge bias system (400) is configured to exert a force on the first cartridge (301 ) to maintain the first cartridge in a defined position, wherein the force is provided by the at least one first resilient member, and wherein the second drug delivery device (1 ) comprises a second cartridge bias system (400) which comprises at least one second resilient member (1 10, 402, 403), wherein the second cartridge bias system (400) is configured to exert a force on the second cartridge (301 ) to maintain the second cartridge in a defined position, wherein the force is provided by the at least one second resilient member, and

wherein the first cartridge bias system comprises a rigid body (401 ) as spacer to compensate the difference in dimension between the first cartridge and the second cartridge.

12. The arrangement of claim 11 ,

wherein the at least one first resilient member (402, 403) and the at least one second resilient member (110, 402, 403) are interchangeable parts and/or wherein the rigid body is a non-interchangeable part.

13. The arrangement of any one of the preceding claims,

wherein the first cartridge unit (300) comprises a first cartridge holder (302), wherein the first cartridge (301 ) is permanently secured within the first cartridge holder and wherein the first cartridge holder is releasably secured to the first housing (10, 20, 350), and

wherein the second cartridge unit (300) comprises a second cartridge holder (302), wherein the second cartridge (301 ) is permanently secured within the second cartridge holder and wherein the second cartridge holder is releasably secured to the second housing (10, 20, 350).

14. The arrangement of any one of the preceding claims,

wherein a first mechanism unit comprises the first housing (10, 20, 350) and the first dose setting and drive mechanism and a second mechanism unit comprises the second housing (10, 20, 350) and the second dose setting and drive mechanism, wherein the first mechanism unit, the first cartridge unit (300), the second mechanism unit, and the second cartridge unit (300) are adjusted to one another such that the first cartridge unit (300) cannot be connected to the second mechanism unit and/or the second cartridge unit (300) cannot be connected to the first mechanism unit,

wherein the first housing (10, 20, 350) and the second cartridge unit (300) have matching guide features (327) which could form a guiding interface to guide movement of the second cartridge unit (300) relative to the first housing (10, 20, 350) to a relative position, where the first housing (10, 20, 350) and the second cartridge unit (300) are connected, and

wherein the second housing (10, 20, 350) and the first cartridge unit (300) have matching guide features (327) which could form a guiding interface to guide movement of the first cartridge unit (300) relative to the second housing (10, 20, 350) to a relative position, where the second housing (10, 20, 350) and the first cartridge unit (300) are connected.

15. The arrangement of any one of the preceding claims,

wherein the second cartridge unit (300) and the first housing (10, 20, 350) are adjusted such that the second cartridge abuts the first housing (10, 20, 350) and/or the rigid body (401 ) of the first cartridge bias system (400) to prevent connection of the second cartridge unit (300) to the first housing (10, 20, 350).

16. The arrangement of claim 13 and of one of claims 14 and 15,

wherein the first cartridge holder (302) has a first cartridge coding structure and the second mechanism unit has a second mechanism coding structure, wherein the coding structures are adjusted to prevent relative movement of the first cartridge holder towards the second housing (10, 20, 350) before the first cartridge unit (300) is connected to the second housing (10, 20, 350).

17. The arrangement of any one of claims 13 to 16,

wherein, when the first cartridge holder (301 ) is connected to the first housing (10, 20, 350), a first portion of the first cartridge holder protrudes from the first housing (10, 20, 350), and wherein, when the second cartridge holder (301 ) is connected to the second housing (10, 20, 350), a second portion of the second cartridge holder protrudes from the second housing (10,

20, 350), wherein the length of the first portion of the first cartridge holder which protrudes from the first housing (10, 20, 350) and the length of the second portion of the second cartridge holder which protrudes from the second housing (10, 20, 350) are identical or substantially identical.

18. A method of producing a first mechanism unit which is configured to be connected to a first cartridge unit (300) to form first a drug delivery device (1 ), comprising the following steps:

- providing a second mechanism unit as a model for the first mechanism unit, the second mechanism unit being configured to be connected to a second cartridge unit (300) which is different from the first cartridge unit (300), wherein the second mechanism unit comprises a second housing (10, 20, 350) and a second dose setting and drive mechanism which is at least partly arranged in the second housing (10, 20, 350), the second dose setting and drive mechanism comprising a plurality of second mechanism members which are movable relative to the second housing (10, 20, 350) and/or relative to one another during a dose setting operation for setting a dose of the second liquid and/or a dose delivery operation for delivering the set dose,

- providing a first housing (10, 20, 350) for the first mechanism unit;

- producing one interchangeable mechanism member in accordance with one of the second mechanism members;

- producing one non-interchangeable mechanism member which is adjusted to the first cartridge unit (300),

- assembling a first dose setting and drive mechanism for the first mechanism unit, the first dose setting and drive mechanism comprising the interchangeable mechanism member and the non-interchangeable mechanism member, and arranging the interchangeable mechanism member and the non-interchangeable mechanism member in the first housing (10, 20, 350).

19. An arrangement of drug delivery devices, comprising

a first drug delivery device (1 ) and a second drug delivery device (1 ), wherein

the first drug delivery device (1 ) comprises

- a first housing (10, 20, 350) having a proximal end and a distal end,

- a first cartridge unit (300) releasably or permanently connected to the first housing (10, 20, 350) or retained in the first housing,

- the first cartridge unit (300) comprising a first cartridge (301 ) containing a first liquid (307), wherein the first cartridge (301 ) comprises a first bung (360) and a first cartridge body (340), the first bung being movable in the distal direction relative to the first cartridge body (340) to dispense the first liquid from the first cartridge (301 ),

- a first dose setting and drive mechanism which is at least partly arranged in the first housing (10, 20, 350), the first dose setting and drive mechanism comprising a plurality of first mechanism members which are movable relative to the first housing (10, 20, 350) and/or relative to one another during a dose setting operation and/or a dose delivery operation, wherein

the second drug delivery device (1 ) comprises

- a second housing (10, 20, 350) having a proximal end and a distal end,

- a second cartridge unit (300) releasably or permanently connected to the second housing (10, 20, 350) or retained in the second housing,

- the second cartridge unit (300) comprising a second cartridge (301 ) containing a second liquid (307), wherein the second cartridge comprises a second bung (360) and a second cartridge body (340), the second bung being movable in the distal direction relative to the second cartridge body to dispense the second liquid from the second cartridge,

- a second dose setting and drive mechanism which is at least partly arranged in the second housing (10, 20, 350), the second dose setting and drive mechanism comprising a plurality of second mechanism members which are movable relative to the second housing (10, 20, 350) and/or relative to one another during a dose setting operation and/or a dose delivery operation, wherein

the first liquid (307) and the second liquid (307) are different, and

a) the first mechanism members and the second mechanism members each comprise at least one interchangeable mechanism member, which could be used to assemble both, the first dose setting and drive mechanism and the second dose setting and drive mechanism, and

the first mechanism members and the second mechanism members each comprise at least one non-interchangeable mechanism member, and/or

b) the first cartridge (301 ) and the second cartridge (301 ) have different dimensions.

20. The arrangement of claim 19, wherein the first mechanism members and the second mechanism members comprise a plurality of interchangeable mechanism members and a plurality of non-interchangeable mechanism members, wherein the number of interchangeable mechanism members is greater than the number of non-interchangeable mechanism members.

21. The arrangement of any one of the preceding claims 19 and 20, wherein the first

mechanism members comprise an arbitrarily selected plurality of or all of the following members or types of members:

- a first piston rod (30) arranged to drive movement of the first bung during the dose delivery operation,

- a first bung interface member (31 ) coupled to the first piston rod and configured to abut the first bung (360);

- a first drive member (40) operatively coupled to the first piston rod (30) to transfer a driving force to the first piston rod;

- a first dose setting member (62) which is movable relative to the first housing (10, 20, 350) to set the size of a dose of first liquid to be delivered from the first cartridge (301 ),

- a first user interface member (70) which is operable by the user for performing the dose setting operation and/or the dose delivery operation,

- a first tracking member (50) coupleable or coupled to a first tracking member path (44), wherein the position of the first tracking member along the first tracking member path is indicative for the volume of first liquid remaining in the first cartridge (301 ) and/or having been dispensed from the first cartridge;

- a first dose indication member (61 ) configured to indicate the size of the set dose,

- a first dosing clutch member (90) configured to couple two first mechanism members during only one of the dose setting operation and the dose delivery operation,

- a first reset clutch member (43) configured to couple two first mechanism members during the dose setting operation and the dose delivery operation,

- a first clicker member (101 , 102) provided to generate an audible and/or tactile feedback during the dose setting operation and/or the dose delivery operation,

and wherein

the second mechanism members comprise an arbitrarily selected plurality of or all of the following members or types of members:

- a second piston rod (30) arranged to drive movement of the second bung (360) during the dose delivery operation,

- a second bung interface member (31 ) coupled to the second piston rod (30) and configured to abut the second bung (360);

- a second drive member (40) operatively coupled to the second piston rod (30) to transfer a driving force to the second piston rod;

- a second dose setting member (62) which is movable relative to the second housing (10, 20, 350) to set the size of a dose of second liquid (307) to be delivered from the second cartridge (301 ),

- a second user interface member (70) which is operable by the user for performing the dose setting operation and/or the dose delivery operation,

- a second tracking member (50) coupleable or coupled to a second tracking member path (44), wherein the position of the second tracking member along the second tracking member path is indicative for the volume of second liquid remaining in the second cartridge (301 ) and/or having been dispensed from the second cartridge (301 );

- a second dose indication member (61 ) configured to indicate the size of the set dose,

- a second dosing clutch member (90) configured to couple two second mechanism members during only one of the dose setting operation and the dose delivery operation,

- a second reset clutch member (43) configured to couple two second mechanism members during the dose setting operation and the dose delivery operation,

- a second clicker member (101 , 102) provided to generate an audible and/or tactile feedback during the dose setting operation and/or the dose delivery operation.

22. The arrangement of claim 21 , wherein the first dose setting and drive mechanism and the second dose setting and drive mechanism consist of first mechanism members and second mechanism members of mutually corresponding types of members.

23. The arrangement of claim 21 or 22,

wherein the following members, if comprised by the first mechanism members and the second mechanism members, are non-interchangeable mechanism members:

- the first and second piston rod (30);

- the first and second bung interface member (31 );

- the first and second drive member (40); and

- the first and second tracking member (50).

24. The arrangement of any one of claims 21 to 23,

wherein the second piston rod (30) has one or more blocking features (39) which are arranged to block movement of the second piston rod (30) in the distal direction relative to the first cartridge body (340).

25. The arrangement of any one of claims 21 to 24,

wherein the following members, if comprised by the first mechanism members and the second mechanism members, are interchangeable mechanism members:

- the first and second user interface member (70);

- the first and second dose indication member (61 );

- the first and second dosing clutch member (90);

- the first and second reset clutch member (43); and

- the first and second clicker member (101 , 102).

26. The arrangement of any one of the preceding claims 19 to 25,

wherein the first drug delivery device (1 ) and the second drug delivery device (1 ) have equivalent outer dimensions and/or outer shape.

27. The arrangement of any one of the preceding claims 19 to 26,

wherein the first cartridge body (340) is shorter than the second cartridge body (340) and has a smaller diameter than the second cartridge body, and wherein the first liquid (307) and the second liquid (307) comprise different drugs or different drug formulations.

28. The arrangement of any one of the preceding claims 19 to 27,

wherein the first housing (10, 20, 350) comprises a plurality of first housing parts which are assembled to one another and wherein the second housing comprises a plurality of second housing parts which are assembled to one another, wherein

one (10) of the second housing parts and one (10) of the first housing parts are interchangeable parts and another one (20, 350) of the second housing parts and another one (20, 350) of the first housing parts are non-interchangeable parts.

29. The arrangement of any one of the preceding claims 19 to 28,

wherein the first drug delivery device (1 ) comprises a first cartridge bias system (400) which comprises at least one first resilient member (402, 403), wherein the first cartridge bias system (400) is configured to exert a force on the first cartridge (301 ) to maintain the first cartridge in a defined position, wherein the force is provided by the at least one first resilient member, and wherein the second drug delivery device (1 ) comprises a second cartridge bias system (400) which comprises at least one second resilient member (1 10, 402, 403), wherein the second

cartridge bias system (400) is configured to exert a force on the second cartridge (301 ) to maintain the second cartridge in a defined position, wherein the force is provided by the at least one second resilient member, and

wherein the first cartridge bias system comprises a rigid body (401 ) as spacer to compensate the difference in dimension between the first cartridge and the second cartridge.

30. The arrangement of claim 29,

wherein the at least one first resilient member (402, 403) and the at least one second resilient member (110, 402, 403) are interchangeable parts and/or wherein the rigid body is a non-interchangeable part.

31. The arrangement of any one of the preceding claims 19 to 30,

wherein the first cartridge unit (300) comprises a first cartridge holder (302), wherein the first cartridge (301 ) is permanently secured within the first cartridge holder and wherein the first cartridge holder is releasably secured to the first housing (10, 20, 350), and

wherein the second cartridge unit (300) comprises a second cartridge holder (302), wherein the second cartridge (301 ) is permanently secured within the second cartridge holder and wherein the second cartridge holder is releasably secured to the second housing (10, 20, 350).

32. The arrangement of any one of the preceding claims 19 to 31 ,

wherein a first mechanism unit comprises the first housing (10, 20, 350) and the first dose setting and drive mechanism and a second mechanism unit comprises the second housing (10, 20, 350) and the second dose setting and drive mechanism, wherein the first mechanism unit, the first cartridge unit (300), the second mechanism unit, and the second cartridge unit (300) are adjusted to one another such that the first cartridge unit (300) cannot be connected to the second mechanism unit and/or the second cartridge unit (300) cannot be connected to the first mechanism unit,

wherein the first housing (10, 20, 350) and the second cartridge unit (300) have matching guide features (327) which could form a guiding interface to guide movement of the second cartridge unit (300) relative to the first housing (10, 20, 350) to a relative position, where the first housing (10, 20, 350) and the second cartridge unit (300) are connected, and

wherein the second housing (10, 20, 350) and the first cartridge unit (300) have matching guide features (327) which could form a guiding interface to guide movement of the first cartridge unit (300) relative to the second housing (10, 20, 350) to a relative position, where the second housing (10, 20, 350) and the first cartridge unit (300) are connected.

33. The arrangement of any one of the preceding claims 19 to 32,

wherein the second cartridge unit (300) and the first housing (10, 20, 350) are adjusted such that the second cartridge abuts the first housing (10, 20, 350) and/or the rigid body (401 ) of the first cartridge bias system (400) to prevent connection of the second cartridge unit (300) to the first housing (10, 20, 350).

34. The arrangement of claim 31 and of one of claims 32 and 33,

wherein the first cartridge holder (302) has a first cartridge coding structure and the second mechanism unit has a second mechanism coding structure, wherein the coding structures are adjusted to prevent relative movement of the first cartridge holder towards the second housing (10, 20, 350) before the first cartridge unit (300) is connected to the second housing (10, 20,

350).

35. The arrangement of any one of claims 31 to 34,

wherein, when the first cartridge holder (301 ) is connected to the first housing (10, 20, 350), a first portion of the first cartridge holder protrudes from the first housing (10, 20, 350), and wherein, when the second cartridge holder (301 ) is connected to the second housing (10, 20, 350), a second portion of the second cartridge holder protrudes from the second housing (10, 20, 350), wherein the length of the first portion of the first cartridge holder which protrudes from the first housing (10, 20, 350) and the length of the second portion of the second cartridge holder which protrudes from the second housing (10, 20, 350) are identical or substantially identical.