Medication delivery device

The present invention relates to a medication delivery device, to dosing mechanisms suitable for use in such medication delivery device, in particular in pen-type injectors, preferably having a dose setting member and a drive device enabling the dose setting and the administration of a medicinal product from a multi-dose medication cartridge, to methods using such device, and to methods of manufacturing and assembly of such device.

The present invention relates to a medication delivery device, a use of the device and a method of manufacturing or assembling the device. The invention refers particularly to dosing mechanisms suitable for use in such medication delivery devices, in particular in pen-type injectors, preferably having a dose setting member and a drive device enabling the dose setting and the administration of a medicinal product from a multi-dose medication cartridge. In particular, the present invention relates to such medication delivery devices where a user may set and dispense a dose of medication to be delivered from a multi-dose cartridge. Most preferably, the medication delivery device comprises a multi-dose medication cartridge which can be replaced when the medication has been fully dispensed.

The present invention further relates to a dosing mechanism for a medication delivery device, and particularly to a dosing mechanism comprising a dose setting limiting mechanism with a dose limiting member which prevents the setting of a dose of medication which exceeds a maximum amount of medicament to be dispensed from a medication receptacle, essentially the total amount of medication contained in the medication receptacle of the medication delivery device. Most preferably the dose limiting member interacts (e.g. moves into abutment) with a stop element of the piston rod of the medication delivery device in order to limit the movement of a dose setting member for increasing a set dose of medication to be delivered when a user tries to set a dose exceeding the content remaining in the medication receptacle.

Such medication delivery devices have application where regular injections by persons without formal medical training occur, i.e., patients. This is increasingly common amongst those having diabetes where self-treatment enables such persons to conduct effective management of their diabetes.

These circumstances set a number of requirements for medication delivery devices of this kind. The device must be robust in construction, yet easy to use in terms of the manipulation of the parts, understanding by a user of its operation and the delivery of the required dose of medicament. Dose setting must be easy and unambiguous. In the case of those with diabetes, many users will be physically infirm and may also have impaired vision requiring the dosing mechanism to have a drive device which requires a low dispensing force and the medication delivery device to have an easy to read dose setting display.

As a result of environmental and economical reasons this kind of medication delivery device has been developed to allow only a part of the device to be discarded after all the medicament has been delivered, usually the medication cartridge only. This provides the additional requirement for such a medication delivery device that the resetting of the drive mechanism, when a new cartridge is attached to or inserted into the medication delivery device, needs to be easy and unambiguous without the need for the user to touch any component of the drive mechanism directly, thereby reducing the possibility of damage to the drive mechanism through e.g. contamination.

A further requirement of multi-dose medication delivery devices with means for setting variable doses to be delivered is to indicate to a user if he is attempting to set a dose of medication having a larger size than what is remaining in the medication receptacle (e.g. a medication cartridge). The user should further be prevented from setting a dose which exceeds the amount of medication left in the cartridge of the medication delivery device to avoid the potentially dangerous situation of the user believing that the set dose has been entirely injected, even though this is not the case, because the set dose exceeded the amount of medication left in the medication receptacle.

User operated medication delivery devices are well known within the medical field. Furthermore some medication delivery devices with special end-of-content mechanisms are also known in the art.

EP 1250167 B1 discloses a limiting mechanism that prevents setting of a dose that exceeds the amount of liquid left in a cartridge of an injection device. WO 2006/128794 A2 describes an injection device comprising a track and a track follower which track follower is moved along in the track when setting a dose and engages an end-wall of the track when the summarized set doses equal the initial amount of liquid in the reservoir thereby preventing a user from setting a dose larger than the remaining content of the reservoir. WO 2007/017052 A1 is also directed towards a mechanism for preventing setting of a dose which exceeds the amount of medicament in a reservoir in an injection device.

All of these dose setting limiting mechanisms known in the art have the drawback e.g. that they do not allow or at least hinder the resetting of the medication delivery device after the empty reservoir has been replaced by a full reservoir. For resetting such a device the piston rod and the limiting mechanism have to be moveable back into their initial positions without having to overcome a large resistance and with the smallest possible effort for the user.

The object of the invention is to avoid the disadvantages of known medication delivery devices, particularly to provide an alternative dose setting limiting mechanism, most preferably an end-of-content mechanism which can be integrated into a flexible reset mechanism for use in a medication delivery device by means of which the medication delivery device can be reset for re-use when the medication cartridge is replaced.

Another object of the invention is to provide a dose setting limiting mechanism which securely limits the dose setting corresponding to the amount of medicament left in the medication receptacle of the medication delivery device, in particular by locking the dose setting member with the housing, thereby preventing the further movement of the dose setting member in a dose increasing direction with respect to the housing.

The medication delivery device according to the present invention provides a valuable technical alternative for known medication delivery devices. The medication delivery device according to the present invention e.g. has the advantage that the dose setting limiting mechanism securely and precisely limits the setting of a dose corresponding to the maximum amount of medicament to be dispensed from a medication receptacle, especially by the direct interaction of the dose limiting member with the piston rod the position of which is directly related to the amount of medicament left in the medication receptacle. Another advantage of the present invention is that the piston rod can be driven back into the device body when a new cartridge is attached, without the user having to touch any part of the dosing mechanism in particularly without touching any component of the dose setting limiting mechanism, e.g. the dose limiting member. The medication delivery device according to instant invention further provides the advantage of an easy replacement of the medication cartridge almost without application of pressure on the bung of the cartridge during resetting of the device and therefore without pressurization of the medication within the cartridge before the first setting and dispensing of a dose.

According to the invention, a medication delivery device is provided, comprising:a medication receptacle,a dosing mechanism comprisinga piston rod which is moveable in a distal direction for medication deliverya drive device for moving the piston rod in the distal direction for medication delivery,a dose setting member for setting a dose of medication to be delivered anda dose limiting member which prevents the setting of a dose of medication which exceeds an amount of medication contained in the medication receptacle anda housing which houses at least part of the dosing mechanism.The dose limiting member is designed for axial movement in a proximal direction with respect to the piston rod during dose setting and the dose limiting member comprises a first stop element and the piston rod comprises a second stop element, the first and second stop elements stopping an axial movement of the dose limiting member in the proximal direction with respect to the piston rod when the first and second stop elements catch, thereby limiting a movement of the dose setting member for increasing a set dose of medication to be delivered, wherein the dose limiting member and the piston rod only interact directly, when the first and second stop elements catch.

Accordingly, the dose limiting member and the piston rod do not interact directly during the normal use (dose setting and dose delivery) of the medication delivery device as long as the amount of medication within the medication receptacle is sufficient. Only when the user attempts to set a dose which exceeds the amount of medication left in the medication receptacle, the first and second stop elements of the dose limiting member and the piston rod, respectively, catch (e.g. engage or abut), resulting in a direct interaction of the dose limiting member and the piston rod. This interaction of the piston rod and the dose limiting member only in this one case of the “last dose situation” of the device has the advantage, that there is also no interaction between the dose limiting member and the piston rod during resetting of the device (i.e. moving back the piston rod to its initial position when inserting a new cartridge into the device). Therefore, the dose limiting member does not prevent or hinder the resetting of the medication delivery device.

According to a preferred embodiment of the present invention the dose limiting member is engaged with the dose setting member, the dose limiting member stopping a dose increasing movement of the dose setting member when the axial movement of the dose limiting member is stopped. The direct engagement has the advantage of the dose limiting member being able to stop the dose increasing movement of the dose setting member directly and not indirectly via other components of the device. Preferably, the dose limiting member is engaged with the dose setting member by means of a thread or splines.

Alternatively and according to another preferred embodiment, the dose limiting member can e.g. be engaged with an insert of the dose setting member which is prevented from moving with respect to the dose setting member or which is provided for limited movement (i.e. limited axial and/or rotational movement) with respect to the dose setting member. Preferably, the dose limiting member is engaged with the insert of the dose setting member by means of a thread or splines.

According to a preferred embodiment of the present invention the dose limiting member is coupled to or engaged with the dose setting memberso that the dose limiting member is moved in the proximal direction with respect to the housing and with respect to the piston rod during dose setting when the set dose of medication to be delivered is increased andso that the dose limiting member is moved in the distal direction with respect to the housing during medication delivery.

The dose limiting member can e.g. be engaged with the dose setting member via an internal thread of the dose setting member or engaged with a threaded insert of the dose setting member.

Preferably, the dose setting member is a dose dial sleeve which is threadedly engaged with the housing and therefore rotates and moves proximally with respect to the housing during setting of a higher dose, rotates and moves distally with respect to the housing during reducing the set dose and rotates and moves distally with respect to the housing during dose delivery.

The dose limiting member is preferably threadedly engaged with the dose setting member or with an insert of the dose setting member, it most preferably comprises an essentially tubular sleeve which is threadedly engaged with the dose setting member or with an insert of the dose setting member.

Preferably, the dose limiting member comprises an opening, wherein the piston rod extends through the opening and the first stop element is provided as a surface surrounding the opening. Most preferably, the dose limiting member comprises an internal flange which has an opening, wherein the piston rod extends through the opening and wherein the internal flange comprises the first stop element. The first stop element is preferably an abutment surface of the internal flange of the dose limiting member. As long as the first stop element does not catch the second stop element of the piston rod, a relative axial movement of the piston rod (within/through the opening of the flange) and the dose limiting member is allowed without interaction of the piston rod and the dose limiting member.

In some embodiments of the present invention the first stop element can comprise a set of teeth or an abutment surface on a flange.

In some embodiments the second stop element is a protrusion which extends radially from the piston rod, the axial position of the protrusion on the piston rod being related to the total amount of medicament to be dispensed from the medication receptacle. The protrusion may e.g. be an outer rim or lug. It is preferably designed such that it catches an abutment surface (e.g. of an internal flange) of the dose limiting member when a setting of a dose is attempted which exceeds the amount of medication contained in the medication receptacle, thereby stopping an axial movement of the dose limiting member in the proximal direction with respect to the piston rod.

According to a particularly advantageous embodiment of the invention the second stop element is the end of a thread on the piston rod. Preferably, the piston rod comprises two threaded regions, a first threaded region which does not influence axial movement of the dose limiting member and a second threaded region, wherein one end of a thread in the second threaded region forms the second stop element. In this embodiment the cross section of the second thread is preferably larger than the cross section of the first thread, the first thread passing through an opening of the dose limiting member without interaction of the piston rod with the dose limiting member and the second thread not passing through the opening but abutting the surrounding edge of the opening. Most preferably, the piston rod comprises two threaded regions, the two threaded regions having threads which are oppositely disposed.

According to a preferred embodiment of the present invention the dose limiting member is allowed to move axially and is prevented from rotation with respect to the housing. Preferably, the dose limiting member is splined to the housing and is thereby prevented from rotation with respect to the housing. Preferably, the dose limiting member is non-rotatable with respect to the housing and piston rod rotates during dose delivery with respect to the housing and with respect to the dose limiting member.

Preferably, the dose limiting member is positioned in the same position with respect to the housing prior to dose setting and after dose delivery, most preferably moving axially in one direction during the setting of a higher dose and in the other direction during the setting of a lower dose and/or during dose delivery. Preferably the distance of axial travelling of the dose limiting member in one direction with respect to the housing from an initial position to the set dose position during dose setting and the distance of axial travelling of the dose limiting member in the other direction with respect to the housing from the set dose position to the initial position during dose delivery are essentially the same. According to a particularly advantageous embodiment of the invention, the dose limiting member and the piston rod travel essentially the same distance in the distal direction during medication delivery.

In some embodiments the medication delivery device according to the present invention further comprises a drive device which is engaged with the piston rod and releasably engaged with the dose setting member. Preferably, the piston rod comprises two threaded regions, the two threaded regions having threads which are oppositely disposed, wherein a second threaded region is provided for threaded engagement with the drive device, preferably a drive sleeve. The first threaded region can e.g. be provided for threaded engagement with a nut means which is non-rotatably attached with or integral of the housing. The releasable engagement between the drive device and the dose setting member (e.g. a drive sleeve and a dose dial sleeve) can e.g. be achieved by means of a clutch mechanism.

In some embodiments the medication delivery device according to the present invention further comprises a clutch means located between the dose setting member and the drive device (preferably between the dose dial sleeve and the drive sleeve) which is provided to releasably couple the drive device with the dose setting member, wherein when the dose setting member and the drive device are coupled, both are allowed to rotate with respect to the housing and when the dose setting member and the drive device are decoupled, rotation of the dose setting member with respect to the housing is allowed, whilst rotation of the drive device with respect to the housing is not allowed and axial movement of the drive device is allowed so that a force is transferred to the piston rod in the distal direction. When the dose setting member and the drive device are decoupled, rotation of the drive device with respect to the housing can e.g. be prevented by the drive device engaging another component of the medication delivery device which is non-rotateable with respect to the housing.

The medication delivery device according to the present invention can e.g. be designed such that the dose limiting member comprises a tubular part which surrounds the piston rod, the drive sleeve and the clutch means and which is surrounded by a dose dial sleeve.

According to a preferred embodiment of the present invention, the dosing mechanism comprises at least one locking member for locking the dose setting member with the housing, thereby preventing further rotation of the dose setting member with respect to the housing in a dose increasing direction, the locking member being activated when the first stop element of the dose limiting member catches the second stop element of the piston rod and when a force (e.g. a torque) is exerted on the dose setting member in the dose increasing direction. The catching of the two stop elements results in stopping the axial movement of the dose limiting member in the proximal direction and thus the dose limiting member stopping the dose increasing movement of the dose setting member. Any further force/torque exerted by the user on the dose setting member is transferred to the at least one locking member and moves the at least one locking member into a locking position in which it locks the dose setting member with the housing. This locking action is an additional feature to prevent a further dose increasing movement of the dose setting member (the dose setting member being stopped by the dose limiting member and by the locking member).

Preferably the locking member interacts directly with or is connected to (i.e. attached to, engaged with or an integral part of) an insert (preferably a threaded insert) of the dose setting member, which insert is in engagement (preferably in threaded engagement) with the dose limiting member and designed for (preferably limited) movement (i.e. axial movement and/or rotational movement) with respect to the dose setting member. This means that the insert and the dose setting member are moveable with respect to each other, but are preferably held in a certain position with respect to each other (e.g. by a biasing means) before the first and second stop elements catch. When the two stop elements abut (thereby preventing a further axial movement of the dose limiting member in the proximal direction), a further force/torque exerted by the user on the dose setting member in the dose increasing direction is preferably transmitted to the insert, thereby moving the insert so that it activates the locking member. The dose setting member can e.g. be allowed to perform a movement (preferably only a small movement) in a dose increasing direction with respect to the insert when the first and second stop elements abut, thereby moving the at least one locking member and at least one locking feature of the housing into engagement.

The medication delivery device may e.g. comprise at least one locking member which interacts directly with or is connected to (i.e. attached to, engaged with or an integral part of) the dose setting member. The locking member(s) can e.g. be separate parts which are each connected to the dose setting member via a swivel axis.

Preferably, the at least one locking member or at least one locking feature of the housing is held in a first deactivated position by a biasing means. In some embodiments the at least one locking member is swivelled out by means of at least one ramp feature when activated, thereby engaging at least one locking feature of the housing. For example, an insert of the dose setting member comprises the at least one ramp feature and the at least one locking member is connected to the dose setting member via a swivel axis. The dose setting member has at least one opening adjacent to the at least one locking member through which the at least one locking member and the at least one ramp feature of the insert can interact. The dose setting member performs a rotational movement in a dose increasing direction with respect to the insert when the end-of content mechanism is activated (e.g. when the first and second stop elements abut, the dose limiting member stopping a further movement of the insert) and the user exerts a further force/torque on the dose setting member in the dose increasing direction, thereby moving the dose setting member with respect to the insert and thus the at least one locking member (preferably against the force of a biasing means) over the at least one ramp feature of the insert, the locking member thereby swivelling out and engaging at least one locking feature of the housing. The at least one locking member is moved into engagement with the locking feature by the ramp feature preferably because the ramp feature slides along a protrusion of the locking member (which can e.g. also be ramp-shaped).

The locking member is preferably automatically (e.g. by the force of a biasing means) disengaged from the locking feature of the housing as soon as the set dose is reduced and/or the user no longer exerts a force/torque on the dose setting member in the dose increasing direction (e.g. when the set dose is dispensed). Preferably a biasing means is provided which holds the locking member in its (de-activated) initial position as long as the end-of-content mechanism is not activated. Most preferably the biasing means thereby also prevents the insert from being moved (e.g. rotated) with respect to the dose setting member (and vice versa) as long as the end-of-content mechanism is not activated, e.g. by pressing a locking member against the ascending slope of a ramp feature of the insert.

The locking members can, alternatively, be integral parts of an insert of the dose setting member, the locking members extending (radially) through openings in the dose setting member. The locking members can for example be made of a flexible material, e.g. a flexible polymeric material. The dose setting member performs a rotational movement in the dose increasing direction with respect to the insert when the end-of content mechanism is activated (e.g. when the first and second stop elements abut) and the user exerts a force on the dose setting member in the dose increasing direction, thereby moving the locking members against an edge of the openings, the locking members thereby swivelling out and engaging locking features of the housing.

According to a preferred embodiment of the present invention the at least one locking member is engaged with grooves or splines in the housing when the locking member is activated, thereby preventing rotation of the dose setting member with respect to the housing in the dose increasing direction.

According to one embodiment the at least one locking member is a hook which is hooked into a hooking feature of the housing when the locking member is activated, thereby preventing rotation of the dose setting member with respect to the housing in the dose increasing direction.

In some embodiments the locking member comprises at least one tooth, preferably a plurality of teeth, for engaging a locking feature of the housing, e.g. a component with a tooth, preferably with a plurality of teeth. The locking member is connected to (i.e. attached to, engaged with or an integral part of) or interacts directly with the dose setting member. The locking feature is connected to (i.e. attached to, engaged with or an integral part of) or interacts directly with the housing or with an insert of the housing such that a movement (i.e. a rotational and/or axial movement, preferably a rotational movement) of the locking feature with respect to the housing in a dose increasing direction is prevented. Therefore, a movement (i.e. a rotational and/or axial movement, preferably a rotational movement) of the locking member in the dose increasing direction with respect to the housing is prevented when the locking member and the locking feature are engaged, e.g. when the teeth of the locking member and the teeth of the dose limiting member are engaged, thereby preventing a further movement (i.e. a rotational and/or axial movement, preferably a rotational movement) of the dose setting member with respect to the housing in a dose increasing direction.

In this embodiment a biasing means is preferably located between the locking member and the locking feature for keeping the locking member and the locking feature disengaged, preferably the teeth of the locking member and the teeth of the locking feature disengaged, until the locking member is activated (e.g. when the first stop element of the dose limiting member abuts the second stop element of the piston rod and when a further force or torque is exerted on the dose setting member in the dose increasing direction).

According to a preferred embodiment of the present invention the locking member is a first toothed ring connected to a dose dial sleeve and the locking feature is a second toothed ring, the second toothed ring being prevented from rotation with respect to the housing, thereby preventing rotation of the dose dial sleeve with respect to the housing when the two toothed rings are engaged.

The dose dial sleeve preferably has a threaded insert which is engaged with the dose limiting member, the second toothed ring being prevented from moving axially with respect to the threaded insert and the threaded insert being provided for axial movement with respect to the dose dial sleeve when the first and second stop members catch and a further force is exerted on the dose dial sleeve in a dose increasing direction, the first and second toothed rings thereby being moved into engagement.

According to a preferred embodiment of the present invention the dose delivery device further comprises a cartridge which contains the medication, the cartridge comprising a piston which is moved in a distal direction by the piston rod for medication delivery, wherein the dose limiting member and/or the at least one locking member is provided to prevent setting of a dose of medication which exceeds a maximum amount of medication to be dispensed from the cartridge.

The present invention further refers to a medication delivery device comprisinga medication receptacle (e.g. a cartridge filled with a liquid medication),a dosing mechanism comprisinga dose setting member for setting a dose of medication to be delivered anda dose setting limiting mechanism (end-of-content mechanism) which prevents the setting of a dose of medication which exceeds a maximum amount of medication to be delivered from the medication receptacle anda housing which houses at least part of the dosing mechanism,
wherein the dose setting limiting mechanism comprises at least one locking member for locking the dose setting member with the housing, thereby preventing movement of the dose setting member with respect to the housing in a dose increasing direction.

The at least one locking member of this variant of the present invention can be activated e.g. when two components (for example two stop elements as described above or a track follower and an end wall) of the medication delivery device are moved into abutment or engagement during dose setting and when the user then exerts a further force on the dose setting member to move it further in the dose increasing direction. This force is preferably transferred to the locking member in order to be activated and to be brought into a locking state in which the locking member locks the dose setting member with the housing of the dose delivery device, thereby preventing movement (preferably preventing rotation) of the dose setting member with respect to the housing in the dose increasing direction.

In the locking state the at least one locking member can e.g. be radially engaged with the surrounding housing of the medication delivery device (preferably with a locking feature of the housing) or with another component of the device which is not allowed to move in the dose increasing direction with respect to the housing. Alternatively the at least one locking member can in a locking state be prevented from moving in a dose increasing direction (e.g. not allowed to rotate) with respect to the housing e.g. when the locking member is axially engaged with a locking feature of the housing, the locking member preferably beingengaged with the dose setting member directly oran integral part of the dose setting member orengaged with another component which is engaged with the dose setting member.

The at least one locking member according to this embodiment of the present invention is preferably designed similarly to the locking members described above.

The locking feature of the housing can e.g. beengaged with the housing directly oran integral part of the housing orengaged with another component which is engaged with the housing.

According to one preferred embodiment, the locking feature of the housing is further engaged with a moveable insert of the dose setting member, the locking feature being prevented from moving axially with respect to the insert.

The term “medication delivery device” according to instant invention shall mean a single-dose or multi-dose, disposable or re-useable device designed to dispense a dose of a medicinal product, preferably multiple selected doses, e.g. of insulin, growth hormones, low molecular weight heparins, and their analogues and/or derivatives etc. Said device may be of any shape, e.g. compact or pen-type. Dose delivery may be provided through a mechanical (optionally manual) dosing mechanism or electrical dosing mechanism or electromechanical dosing mechanism or stored energy dosing mechanism, such as a spring, etc. Dose selection may be provided through a manual mechanism or electronic mechanism or electromechanical mechanism. Additionally, said device may contain components designed to monitor physiological properties such as blood glucose levels, etc. Furthermore, the said device may comprise a needle or may be needle-free. Preferably, the term “medication delivery device” shall mean a re-useable multi-dose pen-type device having mechanical and manual dose selection and dose delivery mechanisms, which is designed for regular use by persons without formal medical training such as patients. Preferably, the medication delivery device is of the injector-type. Most preferably the medication delivery device is designed to deliver a fluid medication.

The term “dose setting limiting mechanism” or “end-of-content mechanism” according to the present invention shall preferably mean any component and/or components and/or assembly designed to prevent the setting of a dose which exceeds a maximum amount of medication to be dispensed from the medication receptacle of the medication delivery device. Most preferably the term “dose setting limiting mechanism” or “end-of-content mechanism” according to the present invention shall preferably mean any component and/or components and/or assembly designed to prevent the setting of a dose which exceeds the amount of medication left in the medication receptacle at the time when the dose is set.

The term “medication receptacle” in the context of the present invention shall preferably mean a cartridge containing a medication or a cartridge assembly, most preferably a cartridge holder for receiving a cartridge containing a medication. Furthermore, the terms “medication receptacle” and “cartridge” and “cartridge assembly” are exchangeable in the context of the present invention. This means that by using the term “medication receptacle”, any meaning of the terms “cartridge” or “cartridge assembly” is included, and vice versa.

The term “cartridge holder” according to instant invention shall mean any component and/or components designed to house a medicament cartridge containing a medication to be delivered by the medication delivery device. Said cartridge holder may be of any shape, e.g. cylindrical and/or tubular. In general, the cartridge holder may be unitary or a multipart component of a cylindrical tubular or non-tubular shape. It may be made of any suitable material known by a person skilled in the art, e.g. of a transparent material. Further the cartridge holder or an insert of the cartridge holder is preferably provided with engagement means, e.g. helical threads or part threads or bayonet or the like, on an external and/or internal surface of the distal end and/or proximal end of the cartridge holder or the insert designed for engagement with corresponding engagement means located on an exterior and/or interior surface of a housing, an insert of the housing and/or a needle assembly. In a preferred embodiment the cartridge holder is of a unitary tubular design having an external thread located at its proximal end.

The term “housing” according to instant invention shall preferably mean any exterior housing (“housing”, “body”, “shell”) or interior housing (“insert”, “inner body”) having an engaging means, such as a helical thread, spline or any other suitable means known by a person skilled in the art. The housing may be designed to enable the safe, correct, and comfortable handling of the medication delivery device or any of its mechanisms. Usually, it is designed to engage with any of the inner components of the medication delivery device (e.g., a dosing mechanism, cartridge, plunger, piston rod), house, fix, guide, and/or protect by limiting the exposure to contaminants, such as liquid, dust, dirt etc. In general, the housing may be unitary or a multipart component of tubular or non-tubular shape. The exterior housing may also serve to house a cartridge from which a number of doses of a medicinal product may be dispensed.

The terms “stop element” or “stop means” according to instant invention shall mean any feature(s) and/or component(s) of the medication delivery device designed to prevent axial and/or rotational movement of any component and/or components at least in one direction. In a preferred embodiment of instant invention, the term “stop element” shall mean any feature perpendicular to the distal-proximal axis of the medication delivery device (particularly any planar surface feature perpendicular to the distal-proximal axis of the medication delivery device) designed to prevent axial movement of a component in one direction when this component abuts the perpendicular feature. According to another preferred embodiment of the present invention the term “stop element” shall mean any feature which provides a radial or rotational stop designed to prevent rotational movement of a component in one rotational direction when an abutment element of the component abuts the radial or rotational stop feature.

The term “dose limiting member” according to the present invention shall preferably mean a component (“end stop”) of the dosing mechanism which prevents the setting of a dose which exceeds the amount of medication left in the medication receptacle. Preferably the dose limiting member is a component which is secured against rotation but allowed to move axially with respect to a housing and which shall prevent at least one component of the dosing mechanism from rotational and/or axial movement when a final dose has been set, thereby preventing the setting of a dose which exceeds the amount of medication left in the cartridge. Furthermore, the “dose limiting member” shall preferably have a helical thread on an exterior surface designed to engage with an interior helical thread of a dose dial sleeve of the dosing mechanism or of an insert of a dose dial sleeve of the dosing mechanism. Preferably the lead of an external helical thread of the said dose dial sleeve for threaded engagement with the housing shall be greater than the lead of the internal helical thread of the dose dial sleeve for threaded engagement of the said dose limiting member.

The term “engaging” according to instant invention shall mean the interlocking of two or more components of the dosing mechanism/medication delivery device, by means of e.g. a spline, thread, or meshed teeth connection, preferably the interlocking of threads of components (“threadedly engaged”).

The term “engagement means” according to the present invention shall preferably mean any means known to those skilled in the art which can be used to engage two or more components of a medication delivery device, e.g. full or part threads, grooves, engaging elements which mesh with threads and/or grooves or means which form a bayonet lock.

The term “disengaging” according to instant invention shall mean the unlocking of two or more components of the dosing mechanism/medication delivery device. According to one example the term “disengaging” according to instant invention shall mean the unlocking of two or more components of the dosing mechanism/medication delivery device under the force of a biasing means. Two components can also be disengaged by the force of a user of the device, e.g. by a patient unscrewing the medication receptacle from the housing.

The terms “to interact directly” or “direct interaction” according to the present invention shall mean any direct interaction of two components of the medication delivery device which leads to a load/force transmission from one of the components to the other. The term “to interact directly” particularly comprises interactions of two components like one component driving a movement (axial movement and/or rotation) of the other component or like one component stopping or preventing a movement (axial movement and/or rotation) of the other component. Such a direct interaction requires an engagement or at least an abutment of the two components. However, if one component only moves along another component this mere contact between the two components is not interpreted as causing a direct interaction between the two components in the context of the present invention.

The term “biasing means” according to instant invention shall preferably mean any component that is provided for exerting a force on a component and/or components to ensure that the component and/or components are forced together (e.g. into engagement) or forced apart (e.g. out of engagement). Preferably the biasing means may be manufactured from any suitable flexible energy storage material known by a person skilled in the art (e.g. metal, rubber or plastics) and may take any suitable form, e.g., a spring.

The term “distal end” according to instant invention shall mean the end of the device or a component of the device which is closest to the dispensing end of the device. Preferably a needle assembly is provided at the distal end of the medication delivery device of the present invention the needle of which can be inserted into the skin of a patient for medication delivery. The distal direction is therefore the direction from the proximal towards the distal end.

The term “proximal end” according to instant invention shall mean the end of the device or a component of the device which is furthest away from the dispensing end of the device. Preferably a button is provided at the proximal end of the medication delivery device of the present invention which is pushed for dose delivery. The proximal direction is therefore the direction from the distal towards the proximal end.

The term “dose increasing direction” according to the present invention shall preferably mean a direction of movement of the dose setting member with respect to the housing when the set dose is increased. This movement may be an axial and/or a rotational movement of the dose setting member. Preferably the movement is an axial movement in the proximal direction, most preferably an axial movement in the proximal direction in combination with a rotational movement in one rotational direction (clockwise or counterclockwise). In the latter case the movement of the dose setting member in the dose increasing direction can be limited by stopping the movement in the proximal direction and/or by stopping the movement in the rotational direction. A force which is exerted by a user on the dose setting member in the dose increasing direction can e.g. be a torque exerted on the dose setting member with respect to the housing if the dose is increased by winding the dose setting member out of the housing.

The term “dosing mechanism” according to instant invention shall mean any component and/or components and/or assembly designed to allow a user to select and/or set a dose to be dispensed and/or to provide and/or to transmit a force necessary to dispense a dose of a medication. Said dosing mechanism may be composed of mechanical and/or electromechanical and/or electronic components. Additionally, the dosing mechanism may be housed by and/or engaged with the device housing or may be an independent assembly. The dosing mechanism of instant invention preferably comprises a piston rod and a drive device for moving the piston rod in the distal direction for medication delivery. Preferably, the dosing mechanism of instant invention comprises a drive sleeve and a dose dial sleeve. More preferably, the dosing mechanism of instant invention comprises a drive sleeve, a dose dial sleeve, a clutch means, a dose dial grip and a button means.

The term “piston rod” according to instant invention shall mean a component adapted to operate through/within the housing, designed to transmit axial movement (preferably towards the distal end) through/within the medication delivery device, preferably from a drive sleeve to the piston of the cartridge, for the purpose of discharging/dispensing a medication from the cartridge, preferably an injectable product. Said piston rod may be flexible or not. It may be a simple rod, a lead-screw, a part of a rack and pinion system, a part of a worm gear system, or the like. The “piston rod” shall further mean a component having a circular or non-circular cross-section. It may be made of any suitable material known by a person skilled in the art.

In a preferred embodiment, the piston rod comprises at least two, more preferably two, external and/or internal helical threads (threaded sections). In another preferred embodiment of the piston rod according to instant invention, a first helical thread (first threaded section) is located at a distal end and a second helical thread (second threaded section) is located at a proximal end of the said piston rod, whereby the said threads of the threaded sections have opposite dispositions. In another preferred embodiment the piston rod of instant invention comprises at least two threaded sections with threads having the same leads and the same pitches at the distal and the proximal end. In yet another preferred embodiment of instant invention the lead and the pitch of the second helical thread of the piston rod shall be greater than the lead and the pitch of the first helical thread. More preferred, the ratio of the leads of the helical threads of the said first and the second helical threads is in the range of 1:1.01 to 1:20, even more preferred in the range of 1:1.1 to 1:10, most preferred 1:2.3. Preferably, one of the said threads (the thread of the second threaded section) is designed to engage with the drive sleeve. Preferably another of the said threads (the thread of the first threaded section) is designed to engage with a reset element, more preferably with a nut means. According to a most preferred embodiment of the present invention, a first external threaded section of the piston rod with a thread having a smaller lead is designed to engage with an internal thread of a nut means and a second external threaded section of the piston rod with a thread having a larger lead is designed to engage with an internal thread of a drive sleeve. In a further preferred embodiment of instant invention, the piston rod is provided with a stop element designed to limit the proximal axial movement of a dose limiting member. The stop element may e.g. be the start of one of the external threads of the piston rod.

The terms “dose setting member” and “dose dial sleeve” according to instant invention shall preferably mean a component of the medication delivery device which is directly or indirectly used to select/dial a dose of medication to be delivered.

Additionally or alternatively the dose setting member or dose dial sleeve is designed to indicate a selected dose of a dispensable product (medication). This may be achieved by use of markings, symbols, numerals, etc., e.g. printed on the external surface of a sleeve or an odometer, or the like. Most preferably the dose setting member or dose dial sleeve is marked by means of laser printing. In a preferred embodiment of the present invention, the dose setting member, in particular the dose dial sleeve is an essentially tubular component of essentially circular cross-section having either:both an internal and external thread, oran internal thread, oran external thread.

Preferably, the dose setting member, in particular the dose dial sleeve comprises an external thread for engaging an internal thread of the housing or of an insert of the housing. Preferably, the dose setting member, in particular the dose dial sleeve according to instant invention comprises an external helical thread having a lead, which is similar to, preferably the same as the lead of an internal helical thread of the drive sleeve. In a more specific embodiment of instant invention, the dose setting member or dose dial sleeve is provided with a plurality of radially extending stop members adapted to abut a corresponding plurality of radial stops provided within the housing or an insert of the housing. These radial stops are preferably provided for stopping a further winding of the dose setting member or dose dial sleeve out of the housing when a dose is set and/or for stopping the further winding of the dose setting member or dose dial sleeve into the housing when a dose has been dispensed.

The term “drive device” according to the present invention shall preferably mean any component and/or components and/or assembly designed to transmit a force to the piston rod for dispensing a dose of a medication. Said drive device may be composed of mechanical and/or electromechanical and/or electronic components. The drive device may be housed by and/or engaged with the housing or may be an independent assembly. Preferably, the drive device of instant invention comprises a drive sleeve. More preferably, the drive device of instant invention comprises a drive sleeve, a clutch means and a button means.

The term “drive sleeve” according to instant invention shall preferably mean any component for directly or indirectly driving the piston rod in a distal direction for medication delivery, most preferably for driving the piston rod directly. According to a preferred embodiment of the present invention, the drive sleeve is an essentially tubular component of essentially circular cross-section. In a preferred embodiment the drive sleeve is engaged with the piston rod. Preferably the drive sleeve comprises an internal thread for engaging an external thread of the piston rod. The drive sleeve is further preferably releasably coupled to a dose dial sleeve, most preferably by a clutch means.

The term “locking member” according to the present invention shall preferably mean any component(s) integral of, engaged with or connected to the dose setting member (or an insert of the dose setting member) which can be brought from a first deactivated state into a second activated state in which it is (they are) engaged with a locking feature of the housing or a locking feature of any component integral of, engaged with or connected to the housing. The locking member can e.g. be activated by being moved from a first into a second position in which it engages the locking feature or vice versa by the locking feature being moved from a first into a second position in which it engages the locking member. In this activated state the locking member indirectly or preferably directly locks the dose setting member with the housing, thereby preventing a dose increasing movement (preferably a dose increasing rotation) of the dose setting member with respect to the housing. Preferably the locking member is a component (e.g. a finger or hook) which is rotatable about an axis from the first deactivated state into the second activated state and vice versa. Alternatively the locking member can e.g. be a component integral of, engaged with or connected to the dose setting member (or an insert of the dose setting member) which has at least one tooth, preferably a plurality of teeth, and which can be engaged by a locking feature of the housing (preferably a ring having at least one tooth or tooth-shaped recess, preferably a plurality of teeth) which is axially moveable from a first position (deactivated state) into a second position (activated state) with respect to the dose setting member and vice versa.

The term “locking feature” according to the present invention shall preferably mean any component(s) integral of, engaged with or connected to the housing which is prevented from moving in a dose increasing direction with respect to the housing and which can be engaged by a locking member which is integral of, engaged with or connected to the dose setting member (or an insert of the dose setting member), thereby preventing a dose increasing movement (preferably a dose increasing rotation) of the dose setting member with respect to the housing. Preferably the locking feature is at least one protrusion, groove, spline, hook, tooth or the like on the inner surface of the housing or on the inner surface of an insert of the housing.

The term “thread” or “helical thread” according to instant invention shall preferably mean a full or part thread, e.g., a cylindrical spiral rib/groove, located on the internal and/or external surface of a component of the medication delivery device, having an essentially triangular or square or rounded section designed to allow continuous free rotational and axial movement between components. Optionally, a thread may be further designed to prevent rotational or axial movement of certain components in one direction by being non-overhaulable.

The term “lead” according to instant invention shall preferably mean the axial distance a nut would advance in one complete revolution; preferably “lead” shall mean the axial distance through which a component having a helical thread, i.e. dose dial sleeve, drive sleeve, piston rod, etc., of the dosing mechanism travels during one rotation. Therefore the lead is a function of the pitch of the thread of the relevant component.

The term “pitch” according to instant invention shall preferably mean the distance between consecutive contours on a helical thread, measured parallel to the axis of the helical thread.

One aspect of the present invention provides a medication delivery device according to instant invention for dispensing a medicinal product preferably for dispensing a pharmaceutical formulation (e.g. solution, suspension etc.) comprising an active compound selected from the group consisting of insulin, growth hormone, low molecular weight heparin, their analogues and their derivatives.

The medication delivery device according to the present invention can be a pen-type device and/or an injector-type device. The medication delivery device can comprise a needle or be a needle-free device.

The invention further refers to a method of manufacturing or assembling a medication delivery device according to one of the above-mentioned embodiments. This method preferably comprises the step of providing a dose limiting member as described above which is installed within a dosing mechanism.

According to the invention, the use of a medication delivery device according to one of the above-mentioned embodiments of a medication delivery device for dispensing a medicinal product is also provided. The use preferably comprises the dispensing of a pharmaceutical formulation (e.g. a liquid medication like a solution, a suspension etc.) comprising an active compound selected from the group consisting of insulin, growth hormone, low molecular weight heparin, their analogues, and their derivatives.

Without any limitation, the present invention will be explained in greater detail below with reference to the drawings in which:FIGS. 1ato1cshow a cross-sectional view of one embodiment of a medication delivery device according to the invention in three different states;FIGS. 1dand1eshow the medication delivery device according toFIGS. 1ato1cin a state in which the dose limiting member and the piston rod interact in order to prevent the setting of a higher dose.FIGS. 2aand2bshow schematically a cut-out of a medication delivery device according to the present invention comprising at least one locking member.FIG. 3shows a cut-out of cross-section of another embodiment of a medication delivery device according to the present invention comprising a locking member.

Referring first toFIGS. 1ato1c, there is shown a medication delivery device in accordance with the present invention in three different positions.

The medication delivery device1comprises a cartridge holder2and a (exterior) housing3. Preferably the housing3is lacquered. The distal end of the housing3is provided with an insert3A which is immovably attached to the housing. The insert3A is provided with second engagement means4for engaging first engagement means5of the cartridge holder2. The proximal end of the cartridge holder2is provided with first engagement means5for engaging the second engagement means4of the insert3A.

A cartridge6filled with medication from which a number of doses of the medication may be dispensed is provided in the cartridge holder2. A piston7is retained in the cartridge6.

A removable cap (not shown) can be releasably retained over the distal end of the cartridge holder2. Preferably the cap comprises a clip which is snapped onto the cap. The cap can also be lacquered.

The distal end of the cartridge holder2is provided with suitable engaging means8, such as a helical thread, bayonet or the like, for engagement with a suitable needle assembly (not shown) to enable medicament to be dispensed from the cartridge6and injected.

The medication delivery device1according toFIGS. 1ato1ecomprises a dosing mechanism which includes a piston rod17which is moveable in the distal direction for medication delivery. The piston rod17is of generally circular cross-section. A pressure foot18is located at the distal end of the piston rod17. The pressure foot18is preferably made of two separate parts which are snapped together around a distal end portion of the piston rod17. The pressure foot18is disposed to abut the proximal face of the piston7within the cartridge6. The piston rod17is moveable in a distal direction by means of a drive device, thereby pushing the piston7to move axially within the cartridge6in the distal direction for medication delivery. A first thread15is formed at the distal end of the piston rod17(first threaded section15). A second thread16is formed at the proximal end of the piston rod17(second threaded section16). The first thread15and the second thread16are oppositely disposed. Preferably at least one of the first and second threads15,16is a multi-start thread, most preferably both are two-start threads.

The drive device comprises a drive sleeve19which extends about the piston rod17. The drive sleeve19is generally cylindrical. The drive sleeve19is provided at a distal end with a radially extending flange20. A helical groove (thread)21extends along the internal surface of the drive sleeve19. The second thread16of the piston rod17is adapted to work within the helical groove21of the drive sleeve19.

A shoulder22A and an extension22B are formed at the proximal end of the drive sleeve19. The extension22B has reduced inner and outer diameters in comparison to the remainder of the drive sleeve19. A proximal end of the extension22B is provided with a radially outwardly directed flange23.

A clutch24is disposed about the drive sleeve19, between the drive sleeve19and a dose limiting member28(described below). The clutch24is located adjacent the proximal end of the drive sleeve19. The clutch24is generally cylindrical and is provided at the distal end with a series of circumferentially directed saw teeth29. Each saw tooth comprises a longitudinally directed surface and an inclined surface. Towards the proximal end of the clutch24there is located a radially inwardly directed flange30. The flange30of the clutch24is disposed between the shoulder22A of the drive sleeve19and the radially outwardly directed flange23of the extension22B. The proximal end of the clutch24is provided with a plurality of saw teeth31. The clutch24is keyed to the drive sleeve19by way of splines (not shown) to prevent rotation between the clutch24and the drive sleeve19. The clutch24is provided with a plurality of flexible arms32(not shown) that engage a plurality of splines on an interior surface of a dose dial sleeve27(described below).

A clutch plate25and a biasing means26are located between the distal end of the clutch24and the proximal face of the radially extending flange20of the drive sleeve19. In the illustrated embodiment, the biasing means26is a spring. The proximal face of the clutch plate25is provided with a series of circumferentially directed saw teeth33. The clutch plate25is secured against rotation with respect to the housing3. The saw teeth33of the clutch plate25interact with the saw teeth29at the distal end of the clutch24during dose setting (described below).

The dosing mechanism further comprises a dose limiting member28which prevents the setting of a dose of medication which exceeds the amount of medication contained in the cartridge6. The dose limiting member28is disposed about the drive sleeve19, between the drive sleeve19and the dose dial sleeve27. The dose limiting member28is secured against rotation with respect to the housing3and is free to move axially with respect to the housing3. At the distal end of the dose limiting member28a radially extending flange34is provided designed to engage with spline features (not shown) on an interior surface of the housing3. In the illustrated embodiment, the external surface of the dose limiting member28is provided with a helical groove (thread) that extends the full length of the dose limiting member28. The helical groove (thread) is engaged with a threaded insert53of the dose dial sleeve27. An interior surface of the dose limiting member28is provided with a number of spline features (not shown). The clutch plate25is engaged with these spline features and thereby secured against rotation with respect to the housing3

A dose dial sleeve27is provided between the clutch24and the housing3. A helical groove (thread)41is provided about an outer surface of the dose dial sleeve27. The housing3may be provided with a helical rib (thread)42, adapted to be seated in the helical groove (thread)41of the dose dial sleeve27. In the illustrated embodiment, the helical rib (thread)42is formed on an interior surface of an insert43of the housing3. The threaded insert43is secured against rotation and axial movement with respect to the housing3. The helical rib42extends for a single sweep of the inner surface of the insert43. A proximal end of the dose dial sleeve27is provided with an inwardly directed flange in the form of a number of radially extending members45.

The housing3is further provided with a window40(not shown) through which a part of the outer surface of the dose dial sleeve27may be seen. A visual indication of the dose that may be dialed is provided on the outer surface of the dose dial sleeve27. The window40conveniently only allows a visual indication of the dose currently dialed to be viewed. The window can be designed such that it allows an enlarged visual indication of the dose currently dialled to be viewed by acting as a magnifying lens. Preferably the window40is filled with a transparent polymer. Most preferably the window40is part of an insert of the housing3which is made by two component injection moulding, wherein a section with a dark polymer surrounds a section with a transparent polymer. The insert is immovably fixed to the housing, e.g. by means of an adhesive tape.

The threaded insert43of the housing3is provided with a series of radial stop features55,56(not shown). A distal end of the dose dial sleeve27is provided with a plurality of stop features44(not shown) which abut the stop features56of the insert43to prevent the dose dial sleeve27from being wound out of the housing3any further when a maximum dose has been set (e.g.80international units of insulin).

A dose dial grip46is disposed about an outer surface of the proximal end of the dose dial sleeve27. An outer diameter of the dose dial grip46preferably corresponds to the outer diameter of the housing3. The dose dial grip46is secured to the dose dial sleeve27to prevent movement therebetween. The dose dial grip46is provided with central opening47. An annular recess48, located in the proximal end of the dose dial grip46, extends around the opening47.

A button49is provided at the proximal end of the medication delivery device1. In the illustrated embodiment of instant invention, the button49is of generally ‘T’ section, with a stem50. The button49is preferably free to rotate with respect to the housing3. Preferably the button49contains a washer (not shown) made of a friction reducing material (e.g. a friction modified polymer material) in order to reduce the friction between the button and dose dial grip46during dose delivery. The stem50of the button49extends through the central opening47in the dose dial grip46and through the inner diameter of the extension22B of the drive sleeve19. The stem50of the button49is retained for limited axial movement in the drive sleeve19and the clutch24. In the illustrated embodiment, a head51of the button49is generally circular. A skirt52depends from a periphery of the head51. The skirt52is adapted to be seated in the annular recess48of the dose dial grip46.

An internal surface at the distal end of the dose dial sleeve27may be provided with a helical thread (not shown). In the illustrated embodiment, the helical thread of the dose dial sleeve27is provided on an internal surface of the threaded insert53. The insert53is retained within the dose dial sleeve27by means of an end cap54secured to the distal end of the dose dial sleeve27. The end cap54is secured against both rotational and axial movement with respect to the dose dial sleeve27. The helical groove (thread) of the dose limiting member28is engaged with the threaded insert53of the dose dial sleeve27.

The medication delivery device1further comprises nut means11which is a reset element and which has a series of face teeth12on a distal surface and a threaded circular opening13. The first thread15of the piston rod17extends through and is threadedly engaged with the threaded circular opening13of the nut means11. The nut means11is prevented from axial movement in the distal and/or proximal direction with respect to the housing3, e.g. in the proximal direction by means of a web57within the housing3. The web57can be a separate component or can be formed as part of the housing3. In the devices shown inFIGS. 1ato1cthe nut means11is in an operational state in which the nut means11is prevented from rotation with respect to the housing3by means of a locking means9and therefore prevents proximal movement of the piston rod17during dose setting and dose delivery.

In the illustrated embodiment, the medication delivery device1is further provided with a locking means9. The locking means9is secured against rotational movement with respect to the housing3, but the locking means9is free for limited axial movement with respect to the housing3when the housing3is engaged with or disengaged from the cartridge holder2. The locking means9is provided on a proximal surface with a series of face teeth10for engaging the face teeth12of the nut means11. A biasing means14, in the form of a spring, is provided between the proximal face of the locking means9and a web57within the housing.

In the shown embodiments according toFIGS. 1ato1cthe cartridge holder2(medication receptacle) comprises actuation means with ramps, the inclined surfaces of the ramps interacting with inclined surfaces of the locking means9when the cartridge holder2is being connected with the housing3. By this interaction the locking means9is moved into engagement with the nut means11. The actuation means thereby brings the nut means11in the operational state.

Accordingly, when the cartridge holder2(medication receptacle) is engaged with the distal end of the housing3the reset element11is in the operational state and when the cartridge holder2(medication receptacle) is disengaged from the distal end of the housing3the reset element11is in a resetting state

In the operational state the reset element11is prevented from rotation with respect to the housing3, the piston rod17being prevented from moving in a proximal direction, and in the resetting state the reset element11is allowed to rotate with respect to the housing3, the medication delivery device being resettable by rotating the piston rod17in a second rotational direction and moving the piston rod17in the proximal direction.

Operation of the medication delivery device1in accordance with the present invention will now be described.

To dial a dose a user rotates the dose dial grip46, thereby rotating the dose dial sleeve27. During dose dialling the clutch24is engaged with the dose dial sleeve27via the saw teeth31at the proximal end of the clutch24. As the clutch24is engaged with the rotating dose dial sleeve27, the clutch24and the drive sleeve19rotate with the dose dial sleeve27because of the splined engagement of the clutch24and the drive sleeve19.

Audible and tactile feedback of the dose being dialled is provided by the clutch plate25and the clutch24. This feedback is provided by the saw teeth29of the clutch24gliding over the saw teeth33of the clutch plate25during the rotational movement of the clutch24with respect to the housing3. During dose dialling, the clutch plate25is pushed axially towards the proximal end of the device by the biasing means26, thus ensuring that the saw teeth29and33of clutch plate25and clutch24maintain contact. As the clutch plate25is secured against rotation by spline features on the interior surface of the dose limiting member28, which is secured against rotation with respect to the housing, the clutch24rotates relative to the clutch plate25during dose setting. Due to the profile of the saw teeth29and33, preferably triangular, the saw teeth29of the clutch24are able to glide over the saw teeth33of the clutch plate25as the clutch24rotates. Preferably, the ratio of the angular spacing of the saw teeth29of the clutch24and the saw teeth33of the clutch plate25is such that each tooth pitch corresponds to a conventional unit dose, or the like.

The dose dial sleeve27is wound out of the housing3(rotational movement and axial movement in the proximal direction) when a dose to be dispensed is increased because of its engagement with (insert43of) the housing3via the threads41,42. The helical groove41of the dose dial sleeve27and the internal thread21of the drive sleeve19have the same lead. This allows the dose dial sleeve27to extend from the housing3and the drive sleeve19to climb along the second thread16of the piston rod17in the proximal direction at the same rate (rotational movement and axial movement in the proximal direction with respect to the housing3and with respect to the piston rod17).

At the limit of travel, a radial stop (not shown) on the dose dial sleeve27engages with a stop feature56provided on the insert43of the housing3to prevent further movement. During dose setting rotation of the piston rod17is prevented due to the opposing directions of the first and second threads15,16on the piston rod17, the first thread15being engaged with the nut means11and the second thread16being engaged with the drive sleeve19.

The dose limiting member28which is prevented from rotating with respect to the housing3, preferably by means of spline features (not shown), moves axially towards the proximal end of the housing3when the dose dial sleeve27rotates and moves in the proximal direction during dose setting. When a dose is set that can maximally be dispensed from the cartridge6, the radially extending flange34abuts a radial stop element60(protrusion58) formed on the piston rod17, preventing the dose limiting member28from further proximal axial movement and both the dose dial sleeve27and the drive sleeve19from rotating further in the direction for setting a larger dose. This dose limiting mechanism will be explained in further detail below with respect toFIGS. 1dand1e.

Should a user inadvertently dial beyond the desired dosage, the medication delivery device allows the dosage to be dialed down without dispense of medicinal product from the cartridge6. The dose dial grip46is counter rotated for this purpose. This causes the system to act in reverse. The dose dial sleeve27, the clutch24and the drive sleeve19rotate together in the reverse direction. The reverse rotation of the clutch24causes the saw teeth29and33of the clutch24and the clutch plate25to ride over one another to create the clicks corresponding to dialled dose reduction. Preferably the saw teeth29and33are so disposed that the circumferential extent of each saw tooth corresponds to a unit dose.

FIG. 1ashows the medication delivery device in a state before a first dose has been set.FIG. 1bshows the medication delivery device1according toFIG. 1ain a state in which a dose has been set. The dose dial sleeve27is extending proximally from the housing3.

When the desired dose has been dialled, the user may then dispense this dose by depressing the button49. This displaces the clutch24axially towards the distal end of the device with respect to the dose dial sleeve27, thereby decoupling the clutch24from the dose dial sleeve27. However, the clutch24remains keyed in rotation to the drive sleeve19. Therefore the decoupling of the clutch24results in a decoupling of the dose dial sleeve27and the drive sleeve19The dose dial sleeve27and associated dose dial grip46are free to rotate, guided by the helical rib42of the insert43located in the helical groove41of the dose dial sleeve27. During dose delivery the dose dial sleeve27is wound back into the housing3in the distal direction. Audible and tactile feedback or the dose dispensed is provided by the flexible arms of the clutch24and the internal splines of the dose dial sleeve27because of the rotational movement of the dose dial sleeve27with respect to the clutch24.

The pressure of the user on the button49further results in an axial movement of the clutch24in the distal direction without rotation with respect to the housing3. The axial movement of the clutch24moves the clutch plate25distally against the force of the biasing means26until the clutch plate25abuts a shoulder on the drive sleeve19and the clutch24and clutch plate25are engaged such that relative rotation between the clutch24and the clutch plate25is prevented, thus preventing rotation of the clutch24and the drive sleeve19with respect to the housing3during dose delivery. As the clutch plate25is splined to the dose limiting member28to prevent rotation of the clutch plate25with respect to the housing3, the clutch plate25, the clutch24and the drive sleeve19travel together distally but do not rotate.

The axial movement of the clutch24causes the drive sleeve19to move axially in the distal direction. The distal longitudinal axial movement of the drive sleeve19further causes (by means of the internal thread21of the drive sleeve19and the second thread16of the piston rod17) the piston rod17(first threaded section15) to rotate and thus to wind through the opening13in the nut means11, thereby to advance the piston7in the cartridge6.

Once the dialled dose has been dispensed, the dose dial sleeve27is prevented from further rotation by a plurality of rotational stop features (not shown) extending from the dose dial grip46engaging with stop features55located on the insert43of the housing3. In the illustrated embodiment, the rotational stop features extend axially from the dose dial grip46and have an inclined end surface. The zero position is determined by the abutment of one of the axially extending edges of the rotational stop features (not shown) with a corresponding stop55on the insert43.

The rotational movement of the dose dial sleeve27during dose delivery causes the dose limiting member28to move axially in a distal direction back to its initial position within the housing3.

FIG. 1cshows the medication delivery device according toFIGS. 1aand1bafter a dose has been dispensed. The piston rod17and the piston7in the cartridge6have been advanced in the distal direction. The dose dial sleeve27and the dose limiting member28are in their original position with respect to the housing3.

When the final dose has been dispensed, the spent cartridge6may be removed and disposed of. To remove the cartridge6, the cartridge holder2is disengaged from the housing3by disengaging the first and second engagement means5,4. Once the cartridge holder2is disengaged from the housing3, the spent cartridge6can be removed from the cartridge holder2and a new cartridge6can be placed in the cartridge holder2.

For reusing the medication delivery device1it has to be reset by moving the piston rod17proximally into its initial position. As long as the nut means11is in the operational state, the proximal movement of the piston rod17is prevented. Therefore the nut means11has to be brought into the resetting state, in which it is allowed to rotate with respect to the housing3so that the piston rod17can be moved in the proximal direction.

Disengagement of the cartridge holder2from the housing3causes the locking means9, under the force of the biasing means14, to disengage from the nut means11. The locking means9then does not prevent rotation of the nut means11anymore. The nut means11is thus not in the operational state anymore, it is in the resetting state. This allows the nut means11to rotate freely and therefore the piston rod17to be wound back up in the proximal direction.

In order to attach the cartridge holder2containing the new cartridge6on the housing3, the piston rod17has to be moved axially in the proximal direction. This proximal movement may be caused by the piston7of the cartridge6abutting the end of the piston rod17and being moved proximally with respect to the housing3when the cartridge holder2with the cartridge6is moved towards the housing3by the user. The pushing back of the piston rod17by means of the piston7of the new cartridge6which is pushed against the pressure foot18of the piston rod17has the advantage, that the pressure foot18of the piston rod17already abuts the piston7of the cartridge6when the device is reset. Therefore, the priming movement of the piston rod17(to remove air from the cartridge6) can be very small and the loss of medication due to priming thus be kept to a minimum. Alternatively the user may push the piston rod17in the proximal direction e.g. by means of a finger and then attach the cartridge holder2with cartridge6to the housing3. As the nut means11(which is threadedly engaged with the piston rod17) is free to rotate with respect to the housing3in the resetting state the piston rod17is free to rotate and translate proximally until the locking means9and the nut means11engage. The dose limiting member28does not affect the resetting of the piston rod17.

Thus the dosing mechanism of the medication delivery device1according to the present invention is reset into a zero (or no dose delivered) position as indicated inFIG. 1a.

FIGS. 1dand1eshow the medication delivery device according toFIGS. 1ato1cin a state in which the dose limiting member28and the piston rod17interact in order to prevent the setting of a higher dose.

The dose limiting member28is designed for axial movement in a proximal direction with respect to the piston rod17during setting of a higher dose and for axial movement in the distal direction together with the piston rod17during dose delivery. The dose limiting member28is allowed to move axially and is prevented from rotation with respect to the housing3. It is splined to the housing3and is thereby prevented from rotation with respect to the housing3. The piston rod17rotates during dose delivery with respect to the housing3and with respect to the dose limiting member28.

The dose limiting member28comprises a first stop element35and the piston rod17comprises a second stop element36, the first and second stop elements35,36stopping an axial movement of the dose limiting member28in the proximal direction with respect to the piston rod17when the first and second stop elements35,36catch, thereby limiting a movement of the dose dial sleeve27for increasing a set dose of medication to be delivered, The dose limiting member28is provided to stop a dose increasing movement of the dose dial sleeve27when the axial movement of the dose limiting member28is stopped. The dose limiting member28and the piston rod17only interact directly, when the first and second stop elements35,36catch.

Accordingly, the dose limiting member28and the piston rod17do not interact directly during the normal use (dose setting and dose delivery) of the medication delivery device as long as the amount of medication within the cartridge6is sufficient. They are just moved along one another during dose setting. Only when the user attempts to set a dose which exceeds the amount of medication left in the cartridge6, the first and second stop elements35,36of the dose limiting member28and the piston rod17, respectively, catch (e.g. engage or abut), resulting in a direct interaction of the dose limiting member28and the piston rod17. This interaction of the piston rod17and the dose limiting member28only in this one case of the “last dose situation” of the device has the advantage, that there is also no interaction between the dose limiting member28and the piston rod17during resetting of the device (i.e. moving back the piston rod17to its initial position when inserting a new cartridge6into the device). Therefore, the dose limiting member28does not prevent or hinder the resetting of the medication delivery device.

The dose dial sleeve27is threadedly engaged with the housing3and therefore rotates and moves proximally with respect to the housing3during setting of a higher dose, rotates and moves distally with respect to the housing3during reducing of a set dose and rotates and moves distally with respect to the housing3during dose delivery.

The dose limiting member28is connected with the dose dial sleeve27via the threaded insert53of the dose dial sleeve27. The dose limiting member28comprises an essentially tubular sleeve which is threadedly engaged with the insert53of the dose dial sleeve27.

The threaded insert53is secured against axial movement with respect to the dose dial sleeve27by means of an end cap54secured to the distal end of the dose dial sleeve27. The end cap54is secured against both rotational and axial movement with respect to the dose dial sleeve27. The threaded engagement of the dose limiting member28with the insert53and the splined engagement of the dose limiting member28with the housing3which allows only axial movement of the dose limiting member28with respect to the housing3have the effectthat the dose limiting member28is moved in the proximal direction (without rotation) with respect to the housing3and with respect to the piston rod17during dose setting when the set dose of medication to be delivered is increased andthat the dose limiting member28is moved in the distal direction (without rotation) with respect to the housing during medication delivery.

The dose limiting member28(and its first stop element35) therefore preferably changes its position with respect to the piston rod17(and its second stop element36) during setting of a dose and keeps its relative position during the dispensing of a dose.

The lead of the thread between the dose dial sleeve27and the housing3is greater than the lead of the thread between the insert53and the dose limiting member28. Therefore the distance which the dose dial sleeve27travels (during the setting of a dose and during the dispensing of a dose) is greater than the distance which the dose limiting member28travels at the same time. The maximum distance which the dose limiting member can travel proximally along the piston rod17is limited by the axial distance of the first and second stop members35,36which preferably relates to the remaining amount of medication to be dispensed from the medication receptacle of the medication delivery device.

The dose limiting member28comprises an internal flange37which surrounds an opening38, wherein the piston rod17extends through the opening38and wherein the internal flange37comprises the first stop element35(the abutment surface39of the internal flange37). As long as the first stop element35does not catch the second stop element36of the piston rod17, a relative axial movement of the piston rod17(through the opening38of the flange37) and the dose limiting member28is allowed without interaction of the piston rod17and the dose limiting member28.

The second stop element36is a protrusion58which extends radially from the piston rod17, the axial position of the protrusion58on the piston rod17being related to the total amount of medicament to be dispensed. It is designed such that it catches the internal flange37of the dose limiting member28when the setting of a dose is attempted which exceeds the amount of medication contained in the cartridge6, thereby stopping an axial movement of the dose limiting member28in the proximal direction with respect to the piston rod17. The piston rod17is prevented from moving proximally at all times (except during resetting of the medication delivery device, when the cartridge holder2is disengaged from the housing3and the piston rod17can be moved back into its initial position).

The protrusion58which forms the second stop element is the end of a thread on the piston rod17. The piston rod17comprises two threaded regions15,16, a first threaded region15which does not influence axial movement of the dose limiting member28and a second threaded region16, wherein one end of the thread in the second threaded region16forms the second stop element36. In this embodiment the cross section of the second thread16is larger than the cross section of the first thread15, the first thread15passing through an opening38of the dose limiting member28without interaction of the piston rod17with the dose limiting member28and the second thread16not passing through the opening38but abutting the surrounding edge of the opening38(abutment surface39).

The dose limiting member28is positioned in the same position with respect to the housing3prior to dose setting and after dose delivery. It moves axially in one direction during the setting of a higher dose and in the other direction during the setting of a lower dose and/or during dose delivery. The distance of axial travelling of the dose limiting member28in one direction with respect to the housing3from an initial position to the set dose position during dose setting and the distance of axial travelling of the dose limiting member28in the other direction with respect to the housing3from the set dose position to the initial position during dose delivery are essentially the same and the dose limiting member28and the piston rod17travel essentially the same distance in the distal direction during medication delivery.

FIG. 1dshows the medication delivery device1in a state in which a last dose has been set and in which the dose limiting member28prevents the setting of a higher dose. Similar toFIG. 1bthe dialling of this last dose has resulted in the drive sleeve19being wound proximally up the piston rod17, the dose dial sleeve27being wound proximally out of the housing3and the dose limiting member28also being moved in the proximal direction with respect to the housing3. The dose limiting member28therefore moves proximally with respect to the piston rod17. The movement of the dose limiting member28in the axial proximal direction along the piston rod17during dose dialling ends in the abutment of the first and second stop elements36,36. This abutment of the internal flange37on the protrusion58which is formed by the distal end of the second thread15of the piston rod17stops the further axial movement of the dose limiting member28in the proximal direction and thereby stops the further winding of the dose dial sleeve27out of the proximal end of the housing3and therefore prevents the setting of a larger dose. However, in this state the dose limiting member28can still be moved in the dose decreasing direction (wound back distally into the housing3) in order to decrease the set dose. A further movement of the dose dial sleeve27in the dose increasing direction is stopped by the dose limiting member28(the axial movement of which is stopped by the abutting stop elements35,36) because of the threaded engagement between the dose limiting member28and the dose dial sleeve27(in the shown embodiment a threaded engagement of the dose limiting member28with the threaded insert53of the dose dial sleeve27).

After this last dose has been delivered, the medication delivery device is in a state as shown inFIG. 1e. The dose limiting member28has moved back distally into its initial position. The piston rod17has at the same time moved distally (essentially the same distance as the dose limiting member28) for medication delivery. Therefore the first and second stop elements35,36have remained in their abutting state and thus still prevent an axial movement of the dose limiting member28in the proximal direction and thereby the a dose increasing movement of the dose dial sleeve27with respect to the housing3. Accordingly it is not possible to set another dose to be dispensed when the medication delivery device is in this end-of-content position as shown inFIG. 1e. The cartridge6has to be replaced and the medication delivery device1reset in order to use the device again for medication delivery.

FIGS. 2aand2bshow schematically a cut-out of cross-section of one embodiment of a medication delivery device according to the present invention comprising at least one locking member. This delivery device can e.g. be designed as shown inFIGS. 1ato1e.

The cut-out shows an insert53of a dose dial sleeve27, a biasing means63and a housing3.

The medication delivery device further comprises at least one (preferably two, three or four) locking member(s)64for locking the dose dial sleeve27with the housing3, thereby preventing rotation of the dose dial sleeve27with respect to the housing3in a dose increasing direction, the locking member64being activated e.g. when the first stop element35(not shown) of the dose limiting member28(not shown) catches the second stop element36(not shown) of the piston rod (not shown) and when further torque is exerted on the dose dial sleeve27in the dose increasing direction. The catching of the two stop elements35,36results in stopping the axial movement of the dose limiting member27in the proximal direction (as described above with reference to the embodiments shownFIGS. 1ato1e) and thus the dose limiting member28stopping the dose increasing movement of the dose dial sleeve27. Any further force/torque exerted by the user on the dose dial sleeve27is transferred to the at least one locking member64and moves the at least one locking member64into a locking position in which it locks the dose dial sleeve27with the housing3. This locking action is an additional feature to prevent a further dose increasing movement of the dose dial sleeve27(the dose dial sleeve27being stopped by the dose limiting member27and by the locking member64). However, it could also be provided as the only feature for this purpose.

The medication delivery device shown inFIGS. 2aand2bcomprises locking members64which are connected to the dose dial sleeve27. The locking members64are separate fingers which are each connected to the dose dial sleeve27via a swivel axis. The locking members64are held in a first deactivated position (as shown inFIG. 2a) by the biasing means63as long as they are not activated. When the locking members64are activated (as shown inFIG. 2b) they are each swivelled out by means of a ramp feature65, the locking members64thereby engaging at least one locking feature66of the housing3. In the embodiment shown inFIGS. 2aand2bthe threaded insert53comprises the ramp features65, the insert53being located within the dose dial sleeve27. The dose dial sleeve27is allowed to perform a rotational movement about a certain angle in a dose increasing direction67with respect to the insert53when the first and second stop elements35,36abut and the user exerts a force on the dose dial sleeve27in the dose increasing direction, thereby rotating the dose dial sleeve27with respect to the insert53. This relative rotational movement moves the at least one locking member64over the at least one ramp feature65of the insert53(which is prevented from following the rotational movement of the dose dial sleeve27e.g. by a dose limiting member28which is engaged with the insert53), the locking member64thereby swivelling out and engaging at least one locking feature66of the housing3. In the embodiment shown inFIGS. 2aand2bthe locking features66of the housing3are numerous splines which run axially along the inner surface of the housing3and which have a saw-tooth shaped cross-section.

The function of the locking mechanism according toFIGS. 2aand2bhas been described in the context of the embodiment of the medication delivery device according to the present invention as shown inFIGS. 1ato1e. However, such a locking mechanism can be activated by other means in a medication delivery device than by stop members and a dose limiting member. The medication delivery device can therefore comprisea cartridge (not shown),a dosing mechanism comprisinga dose dial sleeve27for setting a dose of medication to be delivered anda dose setting limiting mechanism which prevents the setting of a dose of medication which exceeds a maximum amount of medication to be delivered from the cartridge anda housing3which houses at least part of the dosing mechanism,
wherein the dose setting limiting mechanism comprises at least one locking member64for locking the dose dial sleeve27with the housing3, thereby preventing movement of the dose dial sleeve27with respect to the housing3in a dose increasing direction67. The at least one locking member64of the present invention can be activated e.g. when two components (not shown) of the medication delivery device are moved into abutment or engagement during dose setting and when the user then exerts a force on the dose dial sleeve27to move it further in the dose increasing direction67. This force is transferred to the locking member64in order to be activated and to be brought into a locking state in which the locking member64locks the dose dial sleeve27with the housing3of the dose delivery device, thereby preventing movement (preferably preventing rotation) of the dose dial sleeve27with respect to the housing3in the dose increasing direction67.

FIG. 3shows a cut-out of another embodiment of a medication delivery device according to the present invention comprising a locking member.

The medication delivery device comprises a locking member64which is a clutch ring68. The clutch ring68is connected to or an integral part of the dose dial sleeve27. Preferably, the clutch ring68is connected to the dose dial sleeve by laser welding. Therefore it follows each movement (axially and rotationally) of the dose dial sleeve27. The clutch ring68is a toothed ring with a ring of teeth73which are pointing in the proximal direction.

The medication delivery device further comprises a locking feature66which is a locking ring69. The locking ring69is splined to the housing3and therefore prevented from rotation with respect to the housing3while axial movement of the locking ring69is allowed. The locking ring69is a toothed ring with teeth78which are pointing in the distal direction.

An insert74is provided within the dose dial sleeve27. The insert74is non-rotatably attached to the dose dial sleeve27, e.g. by means of splines. The insert can move axially a certain distance with respect to the dose dial sleeve27as will be described below. The insert74carries an engaging feature75which is in engagement with the locking ring69such that the insert74is allowed to rotate with respect to the locking ring69but prevented from moving axially with respect to the locking ring69. Therefore, the locking ring69follows the axial movement of the insert74.

Furthermore, the insert74is threadedly engaged with a dose limiting member28(thread77). The dose limiting member can only be moved axially without rotating with respect to the housing3. A rotational movement of the insert74with respect to the housing moves the dose limiting member28axially with respect to the housing3due to the threaded engagement between the insert74and the dose limiting member28.

The clutch ring68is provided as a locking member64for locking the dose dial sleeve27with the housing3, thereby preventing further rotation of the dose dial sleeve27with respect to the housing3in a dose increasing direction, the locking member64being activated when the first stop element35of the dose limiting member28catches the second stop element36of the piston rod17and when a further force (a torque) is exerted on the dose dial sleeve27in the dose increasing direction. The catching of the two stop elements35,36results in stopping the axial movement of the dose limiting member28in the proximal direction and thus the dose limiting member28stopping the dose increasing movement of the dose dial sleeve27. Any further force/torque exerted by the user on the dose dial sleeve27is transferred to the at least one locking member64and moves the at least one locking member64with respect to the insert74and the locking feature66into a locking position in which it engages the locking feature66and thereby locks the dose dial sleeve27with the housing3.

The insert74and the dose dial sleeve27are axially moveable with respect to each other, but are held in a certain axial position with respect to each other by a biasing means76until the first and second stop elements35,36catch. Until then, the locking member64is held in a first deactivated position by the biasing means76. When the two stop elements35,36abut (thereby preventing a further axial movement of the dose limiting member28and the locking feature66in the proximal direction with respect to the housing3), a further force/torque exerted by the user on the dose dial sleeve27in the dose increasing direction results in the dose limiting member28holding the insert74and the locking feature66in a certain axial position with respect to the housing while the dose dial sleeve27is moved in the proximal direction with respect to the insert74and the locking feature66so that it activates the locking member64. Locking member64is activated by moving the locking member64(clutch ring68) and the locking feature66(locking ring69) into engagement (teeth73,78engaged).

In this locked state a movement (i.e. a rotational and axial movement) of the locking member64in the dose increasing direction with respect to the housing3is prevented, the locking member64and the locking feature66being engaged, thereby preventing a further movement (i.e. a rotational and axial movement) of the dose dial sleeve27with respect to the housing3in a dose increasing direction.

The locking member64is automatically (by the force of the biasing means76) disengaged from the locking feature66of the housing3as soon as the set dose is reduced and/or the user no longer exerts a force/torque on the dose dial sleeve27in the dose increasing direction (e.g. when the set dose is dispensed).

In this embodiment a biasing means76is preferably located between the locking member64and the locking feature66for keeping the locking member64and the locking feature66disengaged, preferably the teeth73of the locking member64and the teeth78of the locking feature66disengaged, until the locking member64is activated (e.g. when the first stop element35of the dose limiting member28abuts the second stop element36of the piston rod17and when a force or torque is exerted on the dose setting member27in the dose increasing direction).

REFERENCE NUMBERS

1medication delivery device2cartridge holder3housing3Ainsert of the housing4second engagement means5first engagement means6cartridge7piston8engaging means9locking means10face teeth of locking means11reset element/nut means12face teeth of nut means13opening of nut means14biasing means15first thread of piston rod16second thread of piston rod17piston rod18pressure foot19drive sleeve20flange of drive sleeve21internal thread of drive sleeve22Ashoulder22Bextension23flange24clutch25clutch plate26biasing means27dose dial sleeve28dose limiting member29saw teeth at distal end of clutch30flange of clutch31saw teeth at proximal end ofclutch32flexible arms33saw teeth of clutch plate34flange at distal end of doselimiting member35first stop element of doselimiting member36second stop element of pistonrod37internal flange of dose limitingmember38opening of internal flange39abutment surface of internalflange40window41outer helical thread of dose dialsleeve42helical thread of the insert43insert of the housing44stop features on dose dialsleeve45radially extending members46dose dial grip47central opening of dose dial grip48annular recess of dose dial grip49button50stem of button51head of button52skirt of button53threaded insert of dose dialsleeve54end cap55stop features on insert 4356stop features on insert 4357web58protrusion on piston rod60radial stop element on piston rod63biasing means64locking member65ramp feature66locking feature of the housing67dose increasing direction68clutch ring69locking ring73teeth of clutch ring74insert75engaging feature of the insert76biasing means77thread between the dose limitingmember and the insert78teeth of the locking ring