WO2023222495A1

WO2023222495A1 - Drug delivery device with adapted to prevent an unintended dose

Info

Publication number: WO2023222495A1
Application number: PCT/EP2023/062559
Authority: WO
Inventors: Bo Kvolsbjerg
Original assignee: Novo Nordisk A/S
Priority date: 2022-05-16
Filing date: 2023-05-11
Publication date: 2023-11-23

Abstract

A drug delivery device (300) comprising a drive mechanism for expelling an amount of drug comprising a movable drive tube (380) adapted to rotate during dosing. The drive tube further comprises a first retainment guide (384c) extending helically in the axial direction on an outer surface of the drive tube (380), the drive tube (380) is further adapted to be axially moved between: a blocked position, wherein the drive tube (380) is rotationally blocked by the housing (340), and an activated position, wherein the drive tube (380) and the piston rod are allowed to rotate by the housing (340) to expel the amount of drug. The drug delivery device further comprises an activation mechanism for activating the drive mechanism comprising a connector (370) having a first key tab (372c) for engaging the drive tube (380). The drive tube (380) further comprises a blocking tab (387) for preventing unintended activation of the drive mechanism by an engagement between the first key tab (372c) and the blocking tab (387).

Description

DRUG DELIVERY DEVICE WITH ADAPTED TO PREVENT AN UNINTEDED DOSE

The present invention relates to drug delivery devices with a drive mechanism and an activa- tion mechanism, the activation mechanism comprises a connector and the drive mechanism a drive tube adapted to be engaged by and moved by the connector during activation. The present invention further relates to such devices adapted to prevent unintended activation of the drive mechanism. The present invention further relates to such devices wherein the con- nector is retained during delivery of the drug. The present invention further relates to such devices which are adapted for delivering a fixed dose and in particular to multi-use fixed dose devices for delivering a plurality of fixed doses.

BACKGROUND OF THE INVENTION

Drug delivery devices for self-administration of different liquid drug formulation presently exist in various shapes and sizes. Some are adapted for connecting to an infusion set, and some are connectable or integrated with an injection needle. The latter type is referred to as injec- tion devices. Some are durable devices comprising a cartridge with a drug reservoir, wherein the cartridge can be changed. Others are disposable devices that are discarded when the cartridge is empty. Disposable devices can be either multi-dose devices, capable of adminis- tering a plurality of doses, or single dose devices, capable of administering only a single dose of a given size. The latter exists with so-called “Shield activation”, where the cannula is covered by a shield in the front of the device that releases the dose when pressed. The can- nula is then exposed only to enter the skin, when the user presses the device against the skin, and thereby depresses the shield, and releases the dose. These injection devices are disposed after a single injection. For single dose devices, the dose is typically fixed or pre-set whereas for multi-dose device, the user can typically set the desired dose size prior to each injection. However, during recent years there has also been development of multi-dose de- vices, wherein a fixed dose can be administered, see for example WO/2021/122190 which disclosing a multi-use fixed dose drug delivery device with an integrated re-useable needle. To reduce production costs, it is for some purposes desired to use a fixed dose device capa- ble of delivering multiple doses of a fixed volume instead of a single dose.

Fixed dose devices are preferable to some users since they may not feel comfortable with or be capable of operating the device to adjust the correct dose each time. When devices for instance are used by children or older people, simplicity and ease of use is important to avoid user error leading to over- or under dosing. In other cases, the treatment regimen prescribes a fixed dose of e.g., a GLP-1 type of drug. In more detail, WO/2021/122190 discloses a drug delivery device for delivering at least one fixed dose. The disclosed device comprises: a housing assembly, a drug reservoir with a pis- ton and a drive mechanism. The drive mechanism comprises a piston rod for advancing the piston to expel a drug, and a drive tube, wherein the drive mechanism is adapted to deliver the predefined fixed dose or doses in response to activation. The drug delivery device further comprises an activation mechanism for activating a drive mechanism, in response to moving the drive tube in an axial direction. The housing assembly comprises a guide structure for guiding the drive tube during activation and delivery of a dose. The guide structure comprises an axial portion providing a sliding surface for guiding the drive tube during activation, and for providing a rotational stop defining an end of dose. The guide structure further comprises a helical portion providing a sliding surface adapted for guiding the drive tube during dosing. The drive tube is rotated by the drive mechanism in a dosing state, in response to activation of the drive mechanism.

However, if the drive tube is dropped on the floor the drive mechanism may unintentionally be activated. It is therefore an object of the present invention to provide a drug delivery de- vice adapted to alleviate the consequences of such an unintended activation. It is a further object of the present invention to minimize the risk that an unintended activation of the drive mechanism damages the drive mechanism.

DISCLOSURE OF THE INVENTION

In the disclosure of the present invention, embodiments and aspects will be described which will address one or more of the above objects or which will address objects apparent from the below disclosure as well as from the description of exemplary embodiments. Even though prior art discloses devices that could be modified to include the invention according to the present disclosure, such a modification would not be accomplished by a skilled person without the teaching of the present disclosure, as it both requires the acknowledgement of the problem and the solution, which is a part of the teaching of the present disclosure.

In a first aspect of the present invention is provided a drug delivery device comprising: -a housing defining an axial direction between a first and a second end;

-a drive mechanism for expelling an amount of drug comprising a piston rod threadably con- nected to the housing, an axially movable drive tube rotationally locked to the piston rod, the drive tube is adapted to rotate during dosing and further comprises a first retainment guide extending helically in the axial direction on an outer surface of the drive tube, the first retain- ment guide having a first end portion and a second end portion defining a start portion and an end-of-dose portion, respectively, the first retainment guide further defines a first side and a second side, which sides are opposite to each other; the drive tube is further adapted to be axially moved between:

- a blocked position, wherein the drive tube is rotationally blocked by the housing, and

- an activated position, wherein the drive tube and the piston rod are allowed to rotate by the housing to expel the amount of drug; wherein the drug delivery device further comprises an activation mechanism for activating the drive mechanism comprising a connector having a first key tab for engaging the drive tube, wherein the connector is adapted to be axially movable relative to the housing from: -an initial position, through

-an intermediate position, to

-an activated position, wherein, for activating the drive mechanism, the first key tab of the connector is adapted to engage the drive tube in the intermediate position and to move the drive tube from the blocked position to the activated position, in response to moving the connector relative to the drive tube from the initial to the intermediate position, and together with the drive tube to the activated position and thereby move the first key tab from the first side of the start portion to the second side of the start portion of the first retainment guide, whereby the first key tab can be retained on the second side of the first retainment guide during dosing, wherein the drive tube further comprises a blocking tab for preventing unintended activation of the drive mechanism, the blocking tab is positioned on the first side of the start portion of the first retainment guide and is adapted for engaging the first key tab and stopping rotation of the drive tube, in response to moving the connector from the initial to the intermediate po- sition and the drive tube from the blocked to the activated position, whereby the drive tube is prevented from rotating with the key tab (372c) on the first side of the first retainment guide.

Hereby, rotation of the drive tube is prevented when the connector is moved to the intermedi- ate position and the drive tube at the time is moved to the activated position. Such a move- ment could be a result of dropping the device on the floor. If, the drug delivery device is dropped with the above described movement of connector and drive tube, the drive tube will be blocked on the blocking tab and not rotate further until the connector is moved all the way to the activated position. In a further aspect, the first key tab is adapted to be guided along the second side of the first retainment guide during rotation of the drive tube, whereby the first key tab is retained on the second side during dosing to limit axial movement of the connector.

In a further aspect, the drive tube further comprises an activation tab, and the axial distance between the second side of the start portion, and the activation tab defines a first keyhole, which is larger than the axial extension of the first key tab, and wherein the first key tab is adapted to engage the first activation tab, when the connector is moved from the initial to the activated position.

In a further aspect, the housing comprises a first dosing guide extending helically in the axial direction for guiding the drive tube during dosing. As the drive tube engages dosing guide during rotation, the combined rotation and axial movement of the drive tube is determined by the dosing guide.

In a further aspect, the housing further comprises an activation guide extending in the axial direction for guiding the drive tube between the blocked and the activated position, and wherein drive tube is adapted to be guided along the first activation guide and the first dosing guide in a repeatable work cycle. As the drive tube also engages the activation guide during activation, the axial movement followed by the combined rotation and axial movement of the drive tube is determined by the activation guide and the dosing guide.

In a further aspect, a circumferential gap is provided between the end of dose portion of the first retainment guide and the first activation tab, whereby the key tab is allowed to move from the second side to the first side of the end-of-dose portion, in response to the drive tube rotating to the end of the first dosing guide and contacts the first activation guide.

In a further aspect, the drive tube further comprises a second retainment guide extending helically in the axial direction and having a first and a second side, the second retainment guide being arranged parallel to and on the first side of the first retainment guide, whereby the first side of the first retainment guide faces the second side of the second retainment guide, the first key tab is further adapted to retain the second retainment guide and prevent the drive tube from moving to the activated position, when the connector is in the initial posi- tion and the drive tube is in the blocked position. In a further aspect, the connector further comprises a second key tab adapted to be moved from the first to the second side of a start portion of the second retainment guide, wherein the axial distance between the blocking tab and the second side of the second retainment guide on the drive tube is larger than the axial extension of the second key tab, but smaller than the axial extension of the first key tab, whereby the second key tab does not engage the blocking tab during dosing.

In a further aspect, the drive tube can rotate from the activated position and back to the blocked position.

In a further aspect, the connector is adapted to be rotated from a first to a second angular position, wherein the first activation tab is adapted to engage the first key tab during rotation of the drive tube from the activated to the blocked position, whereby the connector can be ro- tated from the first angular position to the second angular position as the drive tube reaches the blocked position.

In a further aspect, the housing comprises a reset guide to rotate the connector from the sec- ond angular position and back to the first angular position, in response to moving the con- nector axially towards the initial position.

In a further aspect, the reset guide comprises a protrusion protruding from an outer surface of the housing and the connector comprises a cut-out with a helical edge adapted to engage the protrusion.

In a further aspect, the drug delivery device further comprises a point-of-no-return lock hav- ing an initial state, and an activated state, wherein the point-of-no-return lock in the activated state is adapted to prevent the connector from moving from the activated position to the initial position in a uniform axial movement, wherein the point-of-no-return lock is adapted to change from the initial state to the activated state, in response to moving the connector from the initial to the activated position.

In a further aspect, the point-of-no-return lock comprises a linear ratchet mechanism be- tween the housing and the connector, the ratchet mechanism comprises at least one ratchet arm and at least one structure with an engageable edge, and wherein changing from the ini- tial to the activated state comprises the at least one ratchet arm travelling over the at least one engageable edge. In a further aspect, the drug delivery device is a multi-use fixed dose device adapted for de- livering a plurality of fixed doses, wherein each dose of the plurality of fixed doses corre- sponds to the amount of drug delivered by the drive mechanism, in response to activation. For such a device, as compared to a single-shot device, it becomes increasingly important that the drive mechanism is not broken due to an unintended activation, as the consequence of unintended activation would be discarding the remaining number of doses.

In a further or alternative aspect, the drive tube is a drive tube assembly comprising a first drive tube member and a second drive tube member, but the first and second drive tube members are coupled to each other and moves together during rotation.

In a further or alternative aspect, the drive tube is a drive tube assembly a proximal drive tube member and a distal drive tube member, but the distal and the proximal drive tube members are coupled to each other and moves together during rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following embodiments of the invention will be described with reference to the draw- ings:

Figure 1A illustrates in perspective view an embodiment of a drug delivery device according to the present disclosure wherein the teaching of the present disclosure can be implemented. In figure 1A the device is illustrated in a capped state.

Figure 1 B illustrates in perspective view the embodiment of figure 1A, wherein the device is uncapped.

Figure 2 illustrates an exploded view of the embodiment of figure 1 A.

Figures 3A and 3B illustrates a perspective view of a cut-through of a housing structure of an embodiment according to the present disclosure.

Figures 4A to 4C illustrates a perspective view of a drive tube of an embodiment according to the present disclosure.

Figures 5A to 5C illustrates a perspective view of a connector of an embodiment according to the present disclosure.

Figures 6A and 6B illustrates a perspective view of an assembly comprising the drive tube, the connector, and a portion of an activation rod of an embodiment according to the present disclosure. Figures 7A-7D illustrates a perspective view of an assembly comprising a drive tube, a con- nector, and a spring base. The figures collectively illustrate the device according to the pre- sent disclosure in an initial state.

Figures 8A-8D illustrate the assembly of figure 7. The figures collectively illustrate a device according to an embodiment of the present disclosure in a first intermediate state.

Figures 9A-9D illustrate the assembly of figure 7. The figures collectively illustrate a device according to the present disclosure in an activated state.

Figures 10A-10D illustrate the assembly of figure 7. The figures collectively illustrate a device according to the present disclosure in a second intermediate state.

Figures 11 A-11 D illustrate the assembly of figure 7. The figures collectively illustrate a device according to the present disclosure in an end-of-dose state.

Figures 12A-12D illustrate the assembly of figure 7. The figures collectively illustrate a device according to the present disclosure in a third intermediate state.

Figures 13A and 13B illustrate the assembly of figure 7 without the spring base. The figures collectively illustrate a device according to the present disclosure in a first unintended acti- vated state.

Figures 14A and 14B illustrate the assembly of figure 7 without the spring base. The figures collectively illustrate a device according to the present disclosure in a second unintended ac- tivated state.

In the figures like structures are mainly identified by like reference numerals. Reference num- bers followed by the letter “a” is used to denote the distal end of the structure, and numbers followed by “b” is used to denote the proximal end. Reference numbers comprising a first number followed by a and a second number is used to denote a functional or structural detail of a structure. In this way the first number indicates a primary (relatively large) struc- ture, and the second number indicates a secondary (relatively small) structure or a specific function. Reference numbers followed by the letters c, d, e, and f indicate features with rota- tional symmetry or a rotational shift. A feature denoted with a c in one figure is not neces- sarily denoted with c in another figure unless it is explicitly stated.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

When in the following terms such as “upper” and “lower”, “right” and “left”, “horizontal” and “vertical” or similar relative expressions are used, these only refer to the appended figures and not necessarily to an actual situation of use. The shown figures are schematic represen- tations for which reason the configuration of the different structures as well as their relative dimensions are intended to serve illustrative purposes only. When the term member is used for a given component it can be used to define a unitary component or a portion of a compo- nent, having one or more functions.

In the following detailed description, numerous specific details are set forth to provide a thor- ough understanding of the present disclosure. However, it will be apparent to one of ordinary skill in the art that the present disclosure may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to unnecessarily obscure aspects of the embodiments.

As used herein, the term distal and proximal end is in analogy with the terminology from anatomy used to describe the end positioned away from or nearest the point of attachment to the body, respectively. Therefore, the distal end of an injection device is defined in a context, where a user holds the device in a ready to inject position, whereby the end with the injection needle will be the distal end and the opposite end will be the proximal end. Furthermore, dis- tal, and proximal ends of individual components of the device is also defined in that context.

As used herein, a proximally oriented surface of a structure is defined as the surface of the device appearing, when the device is viewed along a central axis in a distal direction from a position proximal to the proximal end. A proximally oriented surface has a normal vector wherein the axial component is pointing in the proximal direction. In the same way, a distally oriented face is defined as the face appearing, when the device is viewed along a central axis in the proximal direction from a position distal to the distal end. The normal vector of a distally oriented surface has an axial component pointing in the distal direction.

As used herein, for describing the operation of the device, the operation is divided into states and intermediate states. If more intermediate states are required for the purpose of descrip- tion they are referred to as the first, the second and so forth. If it is clear from the context, the first intermediate state or the second intermediate state may be referred to as an intermedi- ate state.

The present disclosure relates to a drug delivery device for automatically delivering an amount of drug in response to activation. In a particular embodiment, an amount of drug cor- responds to a fixed dose, and the disclosure relates to such devices being further adapted for delivering a plurality of fixed doses, wherein each dose is automatically delivered in re- sponse to activation. In common, the drug delivery device according to the present invention comprises a drive tube, which can be moved axially to an activated position by an activation mechanism for delivering the amount of drug. The activation mechanism further comprises a connector with a key tab for engaging the drive tube. The key tab has two functions: (i) the key tab can engage the drive tube for moving the drive tube to the activated position, and (ii) the key tab can engage the drive tube during delivery for retaining the axial position of the connector.

Two alternatives of such drug delivery device are described in the International Applications PCT/EP2022/053624 and WO/2021/122190. The application PCT/EP2022/053624 is not yet publicly available but describes a multi-use fixed dose drug delivery device with an integrated plurality of needles. The other alternative disclosed in WO/2021/122190 discloses a multi- use fixed dose drug delivery device with an integrated re-useable needle. Both applications are filed by Novo Nordisk. The applications are hereby incorporated by refence.

Figures 1 and 2 illustrate details of such a fixed dose drug delivery device 100 and serves to illustrate the general aspects of the construction and the functioning of the various compo- nents and mechanisms. The device 100 disclosed in figures 1 and 2 are included in the pre- sent disclosure to illustrate a problem relating to unintended activation, which has been real- ized by the inventors of the current application. Even though the device 100 could be modi- fied to include the invention according to the present disclosure, such a modification would not be accomplished by a skilled person without the teaching of the present disclosure, as it both requires the acknowledgement of the problem and the solution, which has not been dis- closed in prior art. The device 100 does not disclose the feature solving the problem, but with the knowledge of the invention disclosed in the present disclosure, the device can be modi- fied to solve the problem. The illustrated drug delivery device 100 comprises an activation mechanism with a shield 110 and a connector 170, a drive mechanism with a drive tube 180, a drop lock mechanism comprising a lock arm 250, a split dose prevention mechanism com- prising a first 184c and a second 184d helical guide formed on an outer surface of the drive tube 180, and a double dose prevention mechanism comprising a rotatable needle drum 210. The helical guides 184c and 184d comprises a first side which has a distally oriented sur- face, and a second side having a proximally oriented surface. As will be clear from the follow- ing description, the problem can be solved by incorporating a blocking tab to the drive mech- anism, which prevent the unintended activation in certain situations.

For the drug delivery device 100, the already included drop lock mechanism prevents unin- tended activation of the drive mechanism when the shield 110 is locked. The shield 110 can be locked by putting on a cap 105, which deflects the lock arm 250. In addition, the double dose prevention mechanism can also lock the shield 110. The double dose prevention mech- anism is adapted for rotating the needle drum 210, after a dose has been delivered. After ac- tivation the outwardly moving shield induces rotation of the needle drum 210, and the needle drum 210 together with the housing can be adapted to lock the shield 110. Upon remounting the cap 105, the cap induces further rotation of the needle drum 210 and thereby unlocks the double dose prevention mechanism. At the same time mounting of the cap, deflects the lock arm 250 and thereby activates the drop lock mechanism. In both situations, the shield 110 is locked, and inadvertent activation of the drive mechanism is prevented.

The shield 110 is biased in the distal direction by a return spring 107. When the cap 105 is off, the lock arm 250 has deflected back to its relaxed position and the shield can be moved against the spring force in the proximal direction. In this situation, the shield 110 can uninten- tionally be accelerated and move proximally to activate the drive mechanism if the drug deliv- ery device 100 is dropped from a certain height. In a distal position of the shield 110 and the connector 170, the connector 170 is adapted to retain the drive tube 180 in a distal position via the second helical guide 184d protruding from an outer surface of the drive tube 180 and a key tab protruding from an inner surface of the connector 170. In the situation wherein the cap is off, the inventors of the present applications contemplated two situations, which can lead to either the delivery of an amount of drug or a broken drug delivery device, respec- tively. In a first situation, the shield 110 is accelerated in the proximal direction to move the connector 170, but the inertial forces acting directly on the drive tube are not sufficient to move the drive tube 180. The drive tube is biased in the distal direction by a compressible torsion spring 108, and this force will to some degree diminish the effect of the proximally ori- ented inertial forces on the drive tube. In the first situation, the shield 110 will initially move proximally together with the connector 170 and relative to the drive tube 180. At a certain po- sition the key tab of the connector 170 engages an activation tab 183 of the drive tube 180 and pushes it proximally to an activated position. The inertial forces of the connector 170 and the shield must exceed the compression force from the spring 108, which also acts on the drive tube 180. If this requirement is fulfilled the accelerated shield and connector can bring the drive tube 180 towards the activated position. The first helical guide 184c protrudes from the outer surface of the drive tube 180 and is adapted for guiding the key tab of the con- nector 170 along the proximal surface. In response to the connector and the shield pushing the drive tube all the way to the activated position, the key tab will move from the first side of the first helical guide 184c to the second side, whereby the delivery of drug can start. The de- scribed analysis of the balance of forces and inertial energy is only to illustrate the overall principles, and the exact result of the consequences of a dropped pen will depend on the density of the different components, friction, the stiffness of the spring etc.

During delivery of an amount of drug, a helical surface 189 of the drive tube 180 engages a helical guide of the housing. If the force from the spring 107 on the connector 170 and the shield, during drug delivery, exceeds the inertial forces on the connector 170 and the shield 110, the guided key tab of the connector 170 is forced to engage the first helical guide 184c. Therefore, the connector 170 will be retained axially by the first helical guide 184c of the drive tube 180, and a full fixed dose, i.e., a full amount of drug, will be delivered even though the connector is pushed distally spring. This first helical guide 184c thereby provides a part of the split-dose prevention mechanism. Therefore, in this first situation realized by the inven- tors, an amount of drug can be inadvertently delivered if the device is dropped when the cap is off. However, the inadvertent delivery will most certainly be noticed due to the amount of expelled drug. Furthermore, if the shock due to the event has not broken any parts of the de- vice, the drug delivery mechanism will function normally for a possible next dose.

However, in the second situation, also realized by the inventors of the present invention, the drive tube 180 may accelerate together with the connector 170 and the shield 110, if the iner- tial forces on the shield, the connector and the drive tube exceed the compressive forces of the return spring 107 and the compressible drive spring 108. In this second situation, the drive tube may move all the way to the activated position without moving from the distal to the proximal side of the first helical guide 184c. In this position, the drive tube 180 will also start to rotate, but the key tab of the connector 170 will not be guided by the first helical guide 184c, as the key tab has not reached a proximal side of the first helical guide 184c. There- fore, the inadvertent event will in this case not result in the delivery of a full dose, and the event may furthermore render the drive mechanism inoperable.

In general, the multi-use fixed dose device 100 is intended to be operated by the user by the following procedure:

1. Prepare the injection device by removing or taking of the cap

2. Insert the back needle into the cartridge by depressing the shield

3. Insert the front needle into the injection site by depressing the shield further

4. Activate the drive mechanism to deliver a dose, by depressing the shield further

5. Pull the front needle out of the injection site and into the shield, by releasing the pressure on the shield, whereby the shield moves outwards toward an extended position 6. Pull the back needle out of the cartridge, by allowing the shield to move further out- wards

7. Position a new injection needle at the active needle position by remounting the cap.

In the below will follow a more systematic and detailed description of the components and the mechanisms. Figure 1A illustrates the multi-use fixed dose drug delivery device 100 with the cap 105 mounted on a tubular elongate housing structure 140. Figure 1 B illustrates the injection device 100 without the cap 105, whereby, as illustrated, a portion of the shield struc- ture 110 and a window 141 in the elongate housing portion are uncovered. The arrow CW indicates the clockwise direction, wherein the clockwise direction is defined as the clockwise direction when the device or a component is viewed from the distally oriented face. The shield 110 is rotationally locked, and only internal components can be forced to rotate.

Figure 2 shows the injection device 100 in an exploded view. Figure 2 illustrates the cap 105, the tubular elongate needle shield structure 110, a plurality of needle assemblies (4 in the il- lustrated example), each needle assembly 220 within the plurality of needle assemblies com- prises a needle hub 225, a needle cannula 224, and a proximal plug assembly 221. Figure 2 further shows, a revolving drum 210, a switcher 230, a cartridge holder 130, a cartridge 290 with a slidably arranged plunger, an activation rod 240, a shield return spring 107, a piston washer 104 or piston head, a nut 106 with an internal thread, the tubular elongate housing structure 140, the connector 170, the drive tube 180 with the first 184c and the second 184d helical guides, a dose drive spring 108, a piston rod 109 with an external thread for engaging the internal thread of the nut 106, and a spring base 165. The piston washer 104 may be substituted by a module measuring relative rotation between the piston rod and the plunger, whereby the delivered dose can be calculated. Figure 2 also illustrates the lock arm 250 be- ing a part of the drop lock mechanism preventing unintentional activation in a capped state, i.e. , wherein the cap 105 is mounted on the elongate housing structure 140.

Housing

The injection device comprises a housing assembly, providing a rigid frame supporting and guiding the other structures. The housing assembly is also sometimes referred to as the housing for using a shorter notation. The housing extends between a first distal end and a proximal second end and thereby defines an axial direction. The housing assembly com- prises the elongate housing structure 140, the cartridge holder 130, the nut 106 and the spring base 165, which are fixedly engaged after assembly. The elongate housing structure 140 is adapted to receive and accommodate the cartridge holder 130, and the cartridge holder 130 is adapted to receive the cartridge 290. The housing comprises an activation guide extending in the axial direction for guiding the drive tube between the blocked and the activated position, and a dosing guide extending helically in the axial direction for guiding the drive tube during dosing. The drive tube can be guided along the activation guide and the dosing guide in a repeatable work cycle.

During assembly the nut 106 is axially adjusted relative to the housing structure 140 to en- sure that there is no clearance between the piston washer 104 and the plunger 291 arranged within the cartridge. This adjustment is also referred to as zero-point adjustment, as de- scribed in WO2021122223 filed by Novo Nordisk. Referring to figure 2, the elongate housing structure 140 comprises the window 141 for inspecting the drug. The cartridge holder 130 also comprises a window 131 for inspecting the drug in the cartridge 290. The window 141 is to be aligned with the window 141 in the assembled state.

Drive mechanism

The drive mechanism is also described in the International Patent Application WO2021122190 filed by Novo Nordisk. The drive mechanism or drug delivery mechanism comprises the piston rod 109, the compressible torsional drive spring 108, and the drive tube 180. The piston rod 109 is threadably connected to the housing assembly, and the drive tube 180 is splined to the piston rod 109, wherein the piston rod 109 and the drive tube rotate to- gether but can move relative to one another in the axial direction. The drive tube 180 is forced to rotate by the drive spring 108, which can be pre-strained to deliver the entire con- tent of the cartridge 290, i.e., the plurality of fixed doses. In an alternative embodiment a strainable drive spring may be used, i.e., a torsional drive spring that can be winded-up by the user.

The housing assembly comprises an axial and a helical guide, for guiding the drive tube dur- ing activation and delivery of a dose. For activating the drive mechanism, the drive tube 180 can be moved along the axial guide in the proximal direction and is thereby movable be- tween a stationary or non-rotatable state at a distal position, wherein the drive tube 180 is ro- tationally blocked by the axial guide of the housing, and an activated state, at the proximal activated position, wherein the drive tube 180 is released from the housing. At the proximal activated position, the drive tube 180 is allowed to rotate together with the piston rod 109, and the drive tube 180 is guided along the helical guide of the housing, whereby the drive tube 180 can perform a helical distal movement. The distal movement of the piston rod 109 is determined by the thread connection with the housing. Activation mechanism

The activation mechanism or triggering mechanism comprises the elongate shield structure 110, the activation rod 240, and the connector 170. As illustrated on figure 2 the activation rod 240 comprises a flexible clip 241, and the connector 170 comprises an outer radially ex- tending connection tab (not visible on figures). The flexible clip forms a snap-lock and cir- cumferentially extending track 242, adapted to receive the connection tab 171. Hereby, the connector 170 is axially locked to the activation rod 240 but allowed to rotate between a first and a second angular position.

Drop lock mechanism

The drop lock mechanism comprises the lock arm 250 adapted to lock the shield 110, when the cap 105 is mounted on the housing. The lock arm 250, is deflected, in response to sliding the cap 105 to its mounted position, whereby the lock arm 250 is deflected from a relaxed position to a blocking position wherein it is in axial alignment with a proximally oriented sur- face of the shield 110. Hereby, the shield is blocked, and activation of the drive mechanism is prevented.

Double dose prevention mechanism

The double dose prevention mechanism comprises the needle drum 210 and the switcher 130. The switcher 130 is rotatably arranged in the shield and switches from a first angular position to a second angular position, in response to activation. In the second angular posi- tion, the switcher is adapted to rotate the needle drum 210, in response to distal movement of the shield. The shield is hereby moved from a first unblocked angular position to a second blocked angular position, wherein proximal movement of the shield 110 is blocked.

Insertion sequence control mechanism

To ensure a certain sequence of inserting the needle at the active position into the cartridge and protruding from the shield, the disclosed drug delivery device can comprise an insertion sequence control mechanism comprising a rotationally and slidably arranged hub 225 com- prising a radially extending finger for engaging a circumferentially extending track in the housing assembly. During proximal movement of the shield the hub 225 can be decoupled from the shield and coupled to the housing, whereby the needle can be first connected to the cartridge and thereafter protrude from the shield. During distal movement of the shield, the hub is decoupled from the housing and coupled to the shield, whereby the needle can be covered by the shield and retracted from the cartridge.

Activation control mechanism

To expel a drug through the needle it is required that the needle is in fluid communication with the reservoir. Therefore, the present disclosure describes a drug delivery device providing an activation control mechanism for controlling the sequence of: (i) fluidly connect- ing an active needle assembly, and (ii) activating the drive mechanism.

Illustrative embodiments

Figures 3-14 collectively discloses components of a first embodiment of a drug delivery de- vice according to the present disclosure for delivering a plurality of fixed doses. However, the skilled person reading the present disclosure will understand that by adjusting an end-of-con- tent mechanism, e.g., the length of a track in the piston rod for axially guiding the drive tube while the two components are rotationally locked to each other, the embodiment can easily be modified to deliver only one dose. A detailed description of the end-of-content mechanism can be found in International Application WO/2021/122219 filed by Novo Nordisk. The com- ponents of the embodiment according to figures 3-14 correspond to the embodiment illus- trated in figure 2 or as described for the multi-use fixed dose drug delivery device with an in- tegrated re-useable needle disclosed in WO/2021/122190. Reference numbers on figure 3- 14, which indicates components and structures which corresponds to components and struc- tures on figure 2, are provided with a reference number which is plus 200. Although it is not illustrated in figure 3-14, the embodiment can also comprise a cap, a needle shield structure attached to an activation rod, a plurality of needle assemblies, a revolving drum, a switcher, a cartridge holder, a cartridge with a drug and a slidably arranged plunger, a shield return spring, a piston washer or piston head, a nut with an internal thread, a compressible torsional drive spring, and a piston rod with an external thread for engaging the internal thread of the nut. The embodiment can also comprise a drop lock mechanism, a double dose prevention mechanism, an insertion sequence control mechanism, and activation control mechanism. The mechanisms may be implemented with variations from the mechanism described in rela- tion to figure 2. Although the complete first embodiment with all components is not illustrated the first embodiment has the reference number 300.

Figure 3 discloses the inner guides of the housing structure 340 for guiding the drive tube, which corresponds to the housing structure 140 illustrated in figure 2. Figures 4 and 5 dis- closes a drive tube 380 and a connector 370, which differs from the drive tube 180 and the connector 170 of figure 2, by the further inclusion of a blocking tab and a corresponding ad- aptation of the first and the second key tab. Figure 6 illustrates details of the interconnection between the drive tube 380 and the connector 370. Figure 7-12 illustrate an activation se- quence, whereby an amount of drug can be delivered. Figure 13-14 illustrate a blocking se- quence wherein the drive tube is blocked by the connector. The blocking sequence illustrate the effect of the present invention. Figure 3A illustrates a cut-through the elongate tubular housing structure 340. The housing of the device comprises the housing structure 340 as well as other parts that are fixedly joint to each other. The housing structure 340 extends from a distal end 340a to a proximal end 340b and defines an axial direction between the two ends. A radial direction is normal to the axial direction, and an angular or circumferential direction is normal to the axial and the radial direction. Figure 3A illustrates the inner surface of the housing structure 340 in a perspective view. The housing has been cut through in the axial direction, and the portion closest to the viewer has been removed. Similarly, figure 3B illustrates the half portion, which has been re- moved in figure 3A.

Figure 3A and 3B illustrate a perspective view of features arranged at the inner surface of the tubular housing structure 340 in an axial cut of the housing. The axial cut is provided in a plane containing a central axial line of the cartridge for the assembled device. Figure 3A shows a window 341c for inspection of the cartridge, and rotationally symmetric windows 341 d can be seen on figure 3B. As illustrated, the tubular housing structure 340 comprises an outer tubular portion 343 and an inner tubular portion 354. The inner tubular portion 154 is integrally connected to the outer tubular portion. As seen on figure 3B, the inner tubular por- tion 354 comprises a first axial guide 356c cut-out in a first proximal edge, and a first helical guide 357c defining the proximally oriented surface of the first proximal edge. The helical guide 357c extends 360 degrees from a proximal end of the axial guide 356c to a distal end of the axial guide 356c. The first axial guide 356c is adapted for guiding the guide tube 380 axially during activation, and the helical guide 357c for guiding the drive tube 380 during dos- ing. Hence the two guides are also referred to as the activation guide 356c and the dosing guide 357c, respectively. Together the activation guide and the dosing guide form a continu- ous path for repeated activation and dose guiding. Figure 3A illustrate a second axial activa- tion guide 356d arranged distally to the first activation guide 356c and at a 180 degrees rota- tion to provide a two-fold rotational functionality symmetry. Figure 3A further illustrate a sec- ond helical dosing guide 357d, which is arranged distal to the first dosing guide 357c. The first activation and dosing guides 356c, 357c are arranged with a first diameter on the first proximal edge, and the second activation and dosing guides 356d, 357d are arranged on a second proximal edge with a second diameter smaller than the first diameter.

Figure 4A to 4C illustrate the drive tube 380 in perspective views from different angles. The drive tube 380 comprises a tubular body with an inner and an outer surface. The figures show a first 383c and a second activation tab 383d protruding from an outer surface and ar- ranged for cooperating with a first and a second key tab 372c, 372d (see figures 5A and 5C) of the connector 370 during activation. The key tab 372c comprises a distally oriented sur- face for engaging a proximal surface of the first activation tab 383c and an axial portion providing a surface oriented in the angular direction for being engaged by the first key tab 383c during dosing. The figure also shows a first or proximal retainment guide 384c in the form of a helical guide protruding from the outer surface of the drive tube 380 and extending helically in the axial direction. The first retainment guide 384c comprises a first side oriented in the distal direction and a second side oriented in the proximal direction. The first retain- ment guide 384c further comprises a first end portion at the distal end defining a start portion and a second portion at the proximal end defining an end-of-dose portion. The first activation tab 383c is positioned proximally to the start portion of the first retainment guide 384c, and the axial distance between the start portion and the activation tab 383c defines a keyhole for a rotational entrance of the first key tab 372c. Therefore, the axial extension of the keyhole is slightly larger than the axial extension of the first key tab 372c. The figure further illustrates axial surfaces 382c, 382d for cooperation with the axial guides 356c, 356d during activation, and helical surface 389c, 389d for cooperation with the helical guides 357c, 357d of the housing during dosing.

The drive tube 380 is provided with inward protrusions 380.2 protruding from an inner sur- face and adapted to engage an axial track of the piston rod. The piston rod is adapted to be slidably arranged in the drive tube, whereby relative axial displacement is allowed, but rela- tive rotation is prevented. The drive tube 380 is provided with a ratchet arm 381 for engaging a toothing inside the tubular spring base 365, and thereby forming a one-way ratchet inter- face.

The torque delivering drive spring is adapted to be arranged inside the drive tube 380. At a distal end the drive spring is attached in a seat in the drive tube 380 and at the proximal end the drive spring is attached in a seat in the spring base 365. The drive spring is winded up or strained during assembly, and thereby stores energy to rotate the drive tube with a sufficient torque and thereby deliver the plurality of doses without further straining.

Figure 5A to 5C shows different perspective view of the connector 370. The connector com- prises a tubular body with an inner and an outer surface. As seen, the connector comprises the first key tab 372c and the second key tab 372d on the inner surface. The connector 370 further comprises a first click or ratchet arm 376 for controlling rotational movement, and a second click or ratchet arm 377 providing a point-of-no-return lock together with a ratchet edge formed on the inner surface of the housing 340. A connection tab 371 is provided on the outer surface of the connector 370 and is adapted for coupling to an activation rod 440 (see figure 6A), whereby the connector is axially fixed to the activation rod but is allowed to rotate. A helical cut-out 373 is provided in the distal end 370a of the connector 370 and is adapted to cooperate with a reset guide on an inner surface of the housing. Hereby, the con- nector 370 is adapted to be guided by the housing and to be moved between (i) an initial po- sition with a first axial and a first angular position, to (ii) an intermediate position at a first in- termediate axial and at the first angular position, to an (iii) activated position at a second axial position and the first angular position, to (iv) an end-of-dose position at the second axial posi- tion and a second angular position, and back to the initial position. The axial movement be- tween the initial and the actuation position is guided by the first click-arm 376 cooperating with an axially extending guiding edge on the inner surface of the housing. During movement form the initial to the actuation position, rotation from the first angular position to the second angular position is prevented by the first click-arm 376, which provides a high resistance against rotation by engaging the axially extending guiding edge until the actuation position has been reached. At the second axial position only a small frictional resistance against rota- tion is provided, as the click-arm has disengaged the axially extending guiding edge. An an- gular torque sufficient to overcome the small frictional resistance, is effected by the engage- ment between the activation guides 383c, 383d and the key tabs 372c, 372d during dosing, wherein torque is transferred from the drive tube 380 to the connector 370. The combined axial movement and rotation of the connector 370 from the end-of-dose position to the initial position is guided by the click-arm 376 and the helical-cut out 373 cooperating with the reset guide. During rotation from the second to the first angular position the click-arm 376 deflects inwardly and reengages the axially extending guiding edge when the second angular position is reached. In other words, the angular momentum provided by the engagement between the helical cut-out 373 and the reset guide is sufficient to bend the first click-arm 376 and rotate the tube back to the first angular position.

Figures 7-12 illustrate the drug delivery device in (i) an initial state, (ii) a first intermediate state, (iii) an activated state, (iv) a second intermediate state, (v) an end-of-dose state, and (vi) a third intermediate state. Each state is illustrated with a perspective view of a portion of the housing 354, the spring base 365, the activation rod 440, the connector 370 and the drive tube 380 from 4 different angle with 90 degrees rotation between each angle. Figure 8A, 8B, 8C and 8D corresponds to the view shown in figure 7A, 7B, 7C and 7D, respectively. Corre- sponding views are used in figures 9-12. Figures 7A to 7D illustrate the initial state, wherein the connector 370 is in a distal or initial position and the drive tube 380 is in a distal, initial or blocked position, wherein the axial sur- face 382 of the drive tube 380 is blocked against the axial surface 356 of the housing (see figures 3 and 4 for identification of the position of the axial surfaces 356, 382). A distal por- tion of the drive tube is received within the inner tubular portion 354 of the housing, and both the inner tubular portion 354 and the drive tube 380 are surrounded by the connector 370. A proximal end of the drive tube 380 is received within a tubular portion of the spring base 365. The activation rod 440 is rotationally connected to the connection tab 371 of the connector 370. In figure 7A, the first key tab 372c is seen through a window in the connector, which is made for illustrative purposes only. As seen, the first key tab 372c retains the distal position of the drive tube 380 through retainment of a second or distal retainment guide 384d. The first key tab 372c is furthermore axially aligned with but separated from, the first activation tab 383c of the drive tube. In figure 7B, the activation rod is covered by the other structures, and is therefore not visible. Figure 7B shows the reset tab 352 engaged with the helical cut- out 373 of the connector. As a not shown return ring biases the connector in the distal direc- tion, the connector is rotationally blocked against the reset key 352. Both clip arms 376 and 377 are also seen. Figure 7C shows the opposite side of the one shown in figure 7A and il- lustrates the second key tab 372d which is arranged distal to the first key tab 372c. The first key tab 372d is axially shorter than the first key tab 372c. The second key tab 372d is axially aligned with the second activation tab 383d, which is arranged distal to the first activation tab 383c. The axial distance between the first and the second key tabs 372c and 372d and the first and the second activation tabs is the same. Figure 7D illustrates the opposite side of fig- ure 7B.

Figures 8A to 8D illustrate the drug delivery device in the first intermediate state, wherein the connector 370 has been moved proximally until the key tabs 372 engages the activation tabs 383. In the intermediate state. The connector is in a first intermediate axial position and the first angular position, and the drive tube is in the blocked position. The engagement between the key tabs 372 and the activation tabs is seen in figure 8A and 8C. Figure 8D reveals the internal structure of inner tubular portion 354 of the housing, as the tubular portion 354 has been cut-through and the portion closest to the viewer has been removed. Figure 8D also il- lustrates a portion of a cut-through of the outer tubular portion 343. As best seen by compar- ing figures 7A and 8A, moving the connector from the initial position to the first intermediate position, results in the first key tab 372c moving axially along the blocking tab 387, whereby the key tab moves from a first or distal side of the first retainment guide 384c to a second or proximal side of the first retainment guide 384c. Figures 9A to 9D illustrate the drug delivery device in the activated state, wherein the con- nector and the drive tube are in their proximal positions. In comparison with the first interme- diate axial position, the connector 370 has been moved further proximally together with the drive tube 380 relative to the housing, until the axial surfaces 382 of the drive tube disengage the axial guides 356 of the housing, whereby the drive tube 380 is allowed to rotate, and due to the torque provided by the drive spring, the drive tube 380 will start to rotate. In the acti- vated state, the connector 370 is in a proximal or activated position, and the drive tube is in a proximal or unblocked position.

Figures 10A to 10D illustrate the drug delivery device in the second intermediate state, wherein the drive tube has rotated almost 360 degrees, whereby the activation tabs 383 con- tacts the key tabs 372. In this state, the connector 370 is still in the activated position. The helical surfaces 389 of the drive tube contacts the helical guides 357 of the housing during rotation. Due to the engagement between the drive tube 380 and the connector, the torque is transferred to the connector 370 and the connector 370 will start to rotate.

Figures 11A to 11 D illustrate the drug delivery device in the end-of-dose state, wherein the drive tube has rotated 360 degrees, whereby a torque has been transferred to the connector 370 and rotated to the end-of-dose position. As seen from figure 10B and 11 B the connector 370 has been rotated relative to the reset key 352, such that it has rotated to the second an- gular position, wherein the reset key 352 can force the connector to rotate towards a proxi- mal end of the cut-out 373, in response to distal movement of the connector 370. Figure 11 D further illustrates the axial surface 382 and the helical surface 389 of the drive tube 380 in the blocked position. On the figure, the helical surface 389 occludes the helical guide 357, whereby they appear as one common line.

Figures 12A to 12D illustrate the drug delivery device in the third intermediate position, wherein the connector has moved to a second intermediate axial position, wherein the cut- out 373 approaches the reset key 352. In response to further movement in the distal direc- tion, the reset key will rotate the connector to the first angular position, whereby the con- nector is back in the initial position and the device is back in the initial state. However, by each work cycle the cartridge will contain a dose less.

Figures 13-14 illustrate the drug delivery device in (vii) a first unintended activated state, and (viii) a second unintended activated state. Each state is illustrated with a perspective view of a portion of the housing 354, the activation rod 440, the connector 370 and the drive tube 380 from 2 different angles with 90 degrees rotation between each angle. Figure 14A and 14B corresponds to the view shown in figure 13A and 13B, respectively.

Figures 13A-13B illustrate the drug delivery device in the first unintended activated state, wherein the connector 370 is positioned in the first intermediate axial position, and the drive tube in the unblocked position. In this state, the first key tap 372c is positioned distal to the first retainment guide 384c instead of proximal, as is the case when the activation has been activated intentionally by moving the shield and the connector 370 into engagement with the drive tube 380, whereby the drive tube 380 can be moved further to the activated position (see figure 9A). In the first unintended activated state, the first key tab 372c is arranged with an axial overlap to the blocking tab 387 of the drive tube 380, whereby rotation of the drive tube will be blocked after rotating a small angle.

Figures 14A-14B illustrate the drug delivery device in the second unintended activated state, wherein the connector 370 is positioned in the first intermediate axial position, and the drive tube has rotated a short angle into a blocked position, wherein the first key tab 372 engages the blocking tab 387. If the connector 370 is moved further from the intermediate position to the activated position rotation of the drive tube 380 will continue, and the dosing will be com- pleted without any damage to the drive mechanism. If the blocking tab was missing, rotation of the drive tube would continue with the first key tab 372c on the first side of the first retain- ment guide. The first key tab 372c will eventually get stuck and the drive mechanism will not be able to deliver the complete dose or a new dose. The first key tab 372c can for example get stuck on the second activation tab 383d.

The first retainment guide 384c comprises a first or distal end defining a start portion, wherein the first key tab 372c is initially guided after activation, and a proximal end or second end defining an end-of-dose portion, wherein the guidance of the first key tab 372c is discon- tinued, when the drive tube 380 approaches an end of dose position. The first retainment guide also comprises a distal or first side and a proximal or second side. As illustrated on fig- ure 13A and 14A, an axial gap or first keyhole is provided between the proximal side of the start portion and the activation tab 383c. The first keyhole is larger than the axial extension of the first key tab 372c, whereby the first key tab 372c is allowed to enter the first keyhole dur- ing rotation in the activated state. As also illustrated, an axial gap or second keyhole is pro- vided between the proximal side of the second retainment guide 384d and the blocking tab 387. The second keyhole is smaller than the axial extension of the first key tab 372c, whereby the first key tab is prevented from entering the second keyhole during rotation in an unintended activated state. Thereby, during drug delivery, in response to setting the device in the activated state, the drive tube 380 will rotate and the first key tab 372c will be guided along the first retainment guide 384c. The second key tab 372d is guided along the second retainment guide 384d, and after 180 degrees rotation, the second key tab 372d will enter the second keyhole. As seen on figure 12A, when the drive tube 380 is in the blocked posi- tion and the connector 370 is in the second angular position, the first key tab 372c is allowed to move from the second side of the first retainment guide 384c to the second side. A similar movement is allowed for the second key tab 372d with respect to the second retainment guide 384d.

A blocking tab 387 extending from the start portion of the first retainment guide is an integral part of the retainment guide. The blocking tab may extend along the entire first retainment guide whereby the first retainment guide would just appear thicker, i.e., have a larger axial extension.

Alternatively, the blocking tab could be separate from the start portion but be positioned dis- tally to the start portion of the first retainment guide. For such an embodiment, the gap be- tween the start portion of the first retainment guide and the blocking tab must be smaller than the axial extension of the key tab of the connector to avoid the key tab from slipping into the gap to be positioned distally to or on the first side of the first retainment guide during dosing.

In an alternative embodiment of the present invention only a single set of a key tab and a corresponding activation tab is used. In that case an unintended activation without a blocking tab would render the device dysfunctional, as the connector would not be rotated to the sec- ond angle, i.e., the key tab would be guided on the first side of the first retainment guide and would not be engaged by the activation tab. Without rotating to the second angle the con- nector cannot retract to the initial position.

Alternatively or additionally, in another embodiment the drug delivery device comprises a connector activated by a proximal push button instead of the distal shield. In such embodi- ments the drug delivery device may or may not be provided with a shield covering the nee- dle. For such a device the proximal end can be referred to as the first end and the distal end as the second end. For a device activated by a distal activation button or a shield, as illustrated with the first em- bodiment 300, the direction of activation is proximal, and the distal end is referred to as the first end and the proximal end as the second end. The drug delivery device 300 is adapted to be activated by a shield corresponding to the shield 110 of the drug delivery device 100.

For a device activated by a side button the definition of first end and the second end would depend on the direction of activation, i.e., which direction defines the movement from the ini- tial to the activation state of the connector.

In one embodiment the drug delivery device comprises a single needle assembly, and in an alternative embodiment the drug delivery device comprises a plurality of needle assemblies.

I one embodiment the drug delivery device is adapted for delivering a fixed dose. In another embodiment the drug delivery device is a multi-use fixed dose device adapted for delivering a plurality of fixed doses, whereby it becomes increasingly important that the drive mecha- nism is not broken due to an unintended activation.

If the drug delivery device is adapted for only delivering a single fixed dose the connector do not need to switch from first angular position to the second angular position. For such an em- bodiment dosing would stop at when the activation tab of the drive tube contacts the activa- tion tab of the connector, after an almost complete rotation. For such an embodiment the dis- tal retainment guide should not prevent retraction of the connector in the end of dose position defined by contact between the key tab and the activation tab.

In some embodiments the drive tube is a drive tube assembly, e.g., the drive tube could be assembled by a first drive tube member and a second drive tube member, or a proximal drive tube member and a distal drive tube member, but the members are coupled to each other and moves together during rotation.

In the above description of exemplary embodiments, the different structures and means provid- ing the described functionality for the different components have been described to a degree to which the concept of the present invention will be apparent to the skilled reader. The detailed construction and specification for the different components are considered the object of a nor- mal design procedure performed by the skilled person along the lines set out in the present specification.

Claims

1. A drug delivery device (300) comprising:

-a housing (340) defining an axial direction between a first and a second end;

-a drive mechanism for expelling an amount of drug comprising a piston rod threadably con- nected to the housing, an axially movable drive tube (380) rotationally locked to the piston rod, the drive tube (380) is adapted to rotate during dosing and further comprises a first re- tainment guide (384c) extending helically in the axial direction on an outer surface of the drive tube (380), the first retainment guide (384c) having a first end portion and a second end portion defining a start portion and an end-of-dose portion, respectively, the first retainment guide (384c) further defines a first side and a second side, which sides are opposite to each other; the drive tube (380) is further adapted to be axially moved between:

- a blocked position, wherein the drive tube (380) is rotationally blocked by the housing (340), and

- an activated position, wherein the drive tube (380) and the piston rod are allowed to rotate by the housing (340) to expel the amount of drug; wherein the drug delivery device further comprises an activation mechanism for activating the drive mechanism comprising a connector (370) having a first key tab (372c) for engaging the drive tube (380), wherein the connector (370) is adapted to be axially movable relative to the hous- ing (340) from:

-an initial position, through

-an intermediate position, to

-an activated position, wherein, for activating the drive mechanism, the first key tab (372c) of the connector (370) is adapted to engage the drive tube (380) in the intermediate position and to move the drive tube (380) from the blocked position to the activated position, in response to moving the con- nector (370) relative to the drive tube from the initial to the intermediate position, and to- gether with the drive tube to the activated position and thereby move the first key tab (372c) from the first side of the start portion to the second side of the start portion of the first retain- ment guide (384c), whereby the first key tab (372c) can be retained on the second side of the first retainment guide (384c) during dosing, wherein the drive tube (380) further comprises a blocking tab (387) for preventing unintended activation of the drive mechanism, the blocking tab (387) is positioned on the first side of the start portion of the first retainment guide and is adapted for engaging the first key tab (372c) and stopping rotation of the drive tube (380), in response to moving the connector (370) from the initial to the intermediate position and the drive tube (380) from the blocked to the acti- vated position, whereby the drive tube is prevented from rotating with the key tab (372c) on the first side of the first retainment guide (384c).

2. A drug delivery device according to claim 1 , wherein the first key tab (372c) is adapted to be guided along the second side of the first retainment guide (384c) during rotation of the drive tube, whereby the first key tab (372c) is retained on the second side during dosing to limit axial movement of the connector (370).

3. A drug delivery device according to any of the previous claims, wherein the drive tube (380) further comprises an activation tab (383), and wherein the axial distance between the second side of the start portion, and the activation tab (383) defines a first keyhole, which is larger than the axial extension of the first key tab (372c), and wherein the first key tab (372c) is adapted to engage the first activation tab (383c), when the connector (370) is moved from the initial to the activated position.

4. A drug delivery device according to any of the previous claims, wherein the housing (340) comprises a first dosing guide (357c) extending helically in the axial direction for guiding the drive tube during dosing.

5. A drug delivery device according to claim 4, wherein the housing (340) further comprises an activation guide (356c) extending in the axial direction for guiding the drive tube (380) be- tween the blocked and the activated position, and wherein drive tube (380) is adapted to be guided along the first activation guide (356c) and the first dosing guide (357c) in a repeatable work cycle.

6. A drug delivery device according to any of claims 4-5, wherein a circumferential gap is pro- vided between the end of dose portion of the first retainment guide (384c) and the first activa- tion tab (383c), whereby the key tab (372c) is allowed to move from the second side to the first side of the end-of-dose portion, in response to the drive tube (380) rotating to the end of the first dosing guide (357c) and contacts the first activation guide (383c).

7. A drug delivery device according to any of the previous claims, wherein the drive tube (380) further comprises a second retainment guide (384d) extending helically in the axial di- rection and having a first and a second side, the second retainment guide (384d) being arranged parallel to and on the first side of the first retainment guide (384c), whereby the first side of the first retainment guide faces the second side of the second retainment guide, the first key tab (372c) is further adapted to retain the second retainment guide and prevent the drive tube (380) from moving to the activated position, when the connector (370) is in the ini- tial position and the drive tube (380) is in the blocked position.

8. A drug delivery device according to claim 7, wherein the connector (370) further comprises a second key tab (372c) adapted to be moved from the first to the second side of a start por- tion of the second retainment guide (384d), wherein the axial distance between the blocking tab (387) and the second side of the second retainment guide on the drive tube (380) is larger than the axial extension of the second key tab (372d), but smaller than the axial exten- sion of the first key tab (372c), whereby the second key tab (372d) does not engage the blocking tab during dosing.

9. A drug delivery device according to any of the previous claims, wherein the drive tube can rotate from the activated position and back to the blocked position.

10. A drug delivery device according to any of the previous claims, wherein the connector (370) is adapted to be rotated from a first to a second angular position, wherein the first acti- vation tab (383c) is adapted to engage the first key tab (372c) during rotation of the drive tube (380) from the activated to the blocked position, whereby the connector (370) can be ro- tated from the first angular position to the second angular position as the drive tube reaches the blocked position.

11. A drug delivery device according to claim 10, wherein the housing (340) comprises a re- set guide (352) to rotate the connector (370) from the second angular position and back to the first angular position, in response to moving the connector (370) axially towards the initial position.

12. A drug delivery device according to claim 11 , wherein the reset guide (352) comprises a protrusion protruding from an outer surface of the housing (343) and the connector com- prises a cut-out (373) with a helical edge adapted to engage the protrusion.

13. A drug delivery device according to any of the previous claims, wherein the drug delivery device further comprises a point-of-no-return lock having an initial state, and an activated state, wherein the point-of-no-return lock in the activated state is adapted to prevent the connector (370) from moving from the activated position to the initial position in a uniform ax- ial movement, wherein the point-of-no-return lock is adapted to change from the initial state to the activated state, in response to moving the connector (370) from the initial to the acti- vated position.

14. A drug delivery device according to claim 13, wherein the point-of-no-return lock com- prises a linear ratchet mechanism between the housing (343) and the connector (370), the ratchet mechanism comprises at least one ratchet arm (377) and at least one structure with an engageable edge, and wherein changing from the initial to the activated state comprises the at least one ratchet arm travelling over the at least one engageable edge.

15. A drug delivery device according to any of the previous claims, wherein the drug delivery device is a multi-use fixed dose device adapted for delivering a plurality of fixed doses, wherein each dose of the plurality of fixed doses corresponds to the amount of drug del iv- ered by the drive mechanism, in response to activation.