WO2013081539A1

WO2013081539A1 - Medication delivery device

Info

Publication number: WO2013081539A1
Application number: PCT/SE2012/051315
Authority: WO
Inventors: Billy Nilson
Original assignee: Pendose Ab
Priority date: 2011-12-02
Filing date: 2012-11-28
Publication date: 2013-06-06
Also published as: SE1151146A1; SE536276C2

Abstract

A medication delivery device (1) comprises an outer housing (20). A front end (22) of a piston rod (10) is arranged in mechanical contact with a stopper (16) of a medication cartridge (10). The outer housing has housing helical structures (24) and a dose drum (60) has dose drum helical structures (62), both spiraling around the axial direction and protruding radially inwards. The piston rod has surface geometrical structures (43), arranged for mechanically interact with the helical structures. These mechanical interactions allow an extraction relative spiral movement between the piston rod and the outer housing and a dosing relative spiral movement between the piston rod and the dose drum. The dosing relative spiral movement has an opposite spiral direction and a steeper inclination compared to the extraction relative spiral movement. The outer housing has axial parallel grooves (25). A locking mechanism (80) is arranged for locking a portion of the dose drum into one of the parallel grooves.

Description

MEDICATION DELIVERY DEVICE

TECHNICAL FIELD

The present invention relates in general to medication delivery devices and methods therefore and in particular to pen-type injectors.

BACKGROUND

Persons that require regularly provided drug injections are often provided with medication delivery devices adapted to be used by persons without formal medical training. Some non-exclusive, typical, examples can be patients with diabetes, Parkinson's disease, heart problems etc. Such medication devices make self-treatment possible, which enables such patients to control their disease in a way that reduces the impact on the daily life.

Pen-type medication delivery devices have been used for many years and have shown many advantageous properties. There are a number of requirements on such medication delivery devices. One requirement is that the medication delivery device has to be robust in construction. The devices are often carried in different kinds of bags and have to withstand a certain amount of mechanical forces. The medication delivery device also has to be easy to use, both considering the mechanical manipulation and the understanding of the patient of how the device is to be operated. The volume to be injected will typically vary from patient to patient and from time to time and the dose should therefore be possible to control. The dose setting thus has to be easy and unambiguous.

Patient medication delivery devices are typically used only once or in case exchangeable medication cartridges are used, a limited number of times. This implies that the manufacturing costs of the medication delivery devices will be very important. Mass production manufacturing methods are typically to be used. The medication delivery devise should also be easily disposable in an environment friendly way.

In the published International Patent Application WO 2009/ 132781 Al , a medication delivery device is disclosed. The medication delivery device is of a pen-type and is based on the motion of a piston rod within a housing. Outer threads of the piston rod, having one thread at its front end and another thread at its rear end, interact with the internal windings of other parts for controlling the relative motions. A medication dose is set by turning a dosing mechanism in a spiral path. The medication delivery is caused by pressing a rear end of the medication delivery device.

In the published International Patent Application WO 2010/ 1 12409 Al , another drug delivery device of a pen-type is disclosed. A piston rod having a front thread and guideposts at a rear portion is used to transmit axial and rotational forces from a drive mechanism. According to the disclosure, such arrangements would present lower risk for being stuck.

Despite the extensive development within this field of technology, there are still features that are not optimized, in particular with respect to user- friendliness and/or manufacturing costs.

SUMMARY

A general object of the present invention is to improve the user-friendliness of pen-type injectors. A further object of the present invention is to remove or at least reduce the risk for any accidental obstruction by the user itself during the injection phase. The above objects are achieved by arrangements and methods according to the enclosed independent patent claims. Preferred embodiments are defined in dependent patent claims. In general words, in a first aspect, a medication delivery device comprises an outer housing, a medication cartridge, a piston rod, a dose drum and a locking mechanism. The outer housing has a generally elongated shape. The medication cartridge is attached to a front end of the outer housing. The medication cartridge has a cartridge holder, a cartridge container and a stopper. The stopper is arranged movably in an axial direction within the cartridge container for extraction of medication from the medication cartridge container. The piston rod is arranged along the axial direction within the outer housing. A front end of the piston rod is arranged in mechanical contact with the stopper for enabling transfer of a pushing force from the piston rod onto the stopper. The outer housing has housing helical structures. These housing helical structures spiral around the axial direction and protrude radially inwards. The piston rod has surface geometrical structures, arranged for mechanically interact with the housing helical structures. The mechanical interaction between the surface geometrical structures and the housing helical structures allows an extraction relative spiral movement between the piston rod and the outer housing. The dose drum is arranged at least partially within the outer housing and at least partially surrounding the piston rod. The dose drum has dose drum helical structures. These dose drum helical structures spiral around the axial direction and protrude radially inwards. The dose drum helical structures are configured for mechanically interacting with the surface geometrical structures of the piston rod, allowing a dosing relative spiral movement between the piston rod and the dose drum. The dosing relative spiral movement has an opposite spiral direction compared to the extraction relative spiral movement. The dosing relative spiral movement has a steeper axial inclination than the extraction relative spiral movement. The outer housing has furthermore parallel grooves, directed axially in an inner surface of the outer housing. The locking mechanism is arranged for locking at least one portion of the dose drum into one of the parallel grooves of the outer housing.

In a second aspect, a method for operating a medication delivery device comprises rotating of a dose drum in a dosing relative spiral movement relative a piston rod and an outer housing. The dose drum is locked from rotation relative to the outer housing. All parts of the dose drum are pushed in a linear translation along an axial direction of the medication delivery device. The piston rod is moved in an extraction relative spiral movement relative to the outer housing. The moving of the piston rod is performed by mechanical interactions between the piston rod and the outer housing and the dose drum, respectively. The moving of the piston rod is thereby caused by the pushing of the dose drum. The dosing relative spiral movement has an opposite spiral direction compared to the extraction relative spiral movement. The dosing relative spiral movement has a steeper axial inclination than the extraction relative spiral movement. A stopper of a medication cartridge is translated in an axial direction within a cartridge container of the medication cartridge for extraction of medication from the medication cartridge. The stopper is arranged in mechanical contact with a front end of the piston rod for enabling transfer of a pushing force from the piston rod onto the stopper. The translating of the stopper is thereby caused by the moving of the piston rod.

One advantage with the present invention is that all parts that might be exposed for the hand of a user move in a pure translational manner relative to each other, thereby reducing the risk for unintentional extraction obstruction. This is furthermore provided while also providing a geared extraction motion. Further advantages are further discussed in the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further objects and advantages thereof, may best be understood by making reference to the following description taken together with the accompanying drawings, in which:

FIG. 1 is a cross-sectional drawing of an embodiment of a medication delivery device;

FIG. 2 is a cross-sectional drawing of the embodiment of a medication delivery device according to Fig. 1 when a dose has been set;

FIG. 3 is a cross-sectional drawing of the embodiment of a medication delivery device according to Fig. 1 when in a state ready for dose delivery; FIG. 4 is a cross-sectional drawing of the embodiment of a medication delivery device according to Fig. 1 when the dose is given;

FIG. 5 is a cross-sectional drawing of the embodiment of a medication delivery device according to Fig. 1 ready for another dose delivery action;

FIG. 6 is an explosion view of parts of the embodiment of a medication delivery device according to Fig. 1 ;

FIG. 7 is a side view of the embodiment of a medication delivery device according to Fig. 1 ;

FIG. 8 is a flow diagram of steps of an embodiment of a method for operating a medication delivery device;

FIGS. 9A-D are schematic drawings of embodiments of helical structures possible to use at an outer housing and a dose drum, respectively;

FIGS. lOA-C are schematic drawings of embodiments of piston rods;

FIGS. 1 1A-B are schematic drawings of an embodiment of a locking mechanism between a dose drum and an outer housing; and

FIGS. 12- 14 are cross-sectional drawings of another embodiment of a medication delivery device.

DETAILED DESCRIPTION

Throughout the drawings, the same reference numbers are used for similar or corresponding elements.

When operating a pen-type injector, a typical sequence of action is the following. First, a dose is to be set. This is typically performed by turning a rear part of the injector relative the main housing. This turning typically results in that the rear part moves along a spiraling path. The displacement of the rear part corresponds to the set dose. When delivering the medication dose, the typical action by the user is to push the rear part into the housing again. This is typically assumed to be performed e.g. by the thumb of the user, while the remaining hand is used for holding the main housing. An often required property of a pen-type injector is that the extraction of medication is geared. This means that the speed, with which the user pushes the rear part of the injector, is geared down to a lower speed, with which the actual extraction is made. This will, among other things, increase the available force on the extraction mechanism.

In most prior art pen-type injectors, the extraction of medication is performed by pushing the rear end linearly into the outer housing. To this end, the injector is held in one hand and the user typically pushes the rear end by his thumb. In most prior art solutions, only the very outermost part of the injector moves strictly linearly. Other parts of the dose setting arrangements, however, typically perform again different types of spiraling movements. Since such movements are performed inside the palm of the user, it is very easy for the user to accidentally touch such spiraling members of the arrangement and thereby unintentionally counteracting the extraction action. It would therefore be advantageous if all parts that might be exposed for contact with the user hand moves linearly into the main body of the injector during the extraction phase. In the present invention, this is achieved by providing a number of parts that are allowed to move in different ways relative to each other but are prohibited from other relative motions. These relations will be further explained by the exemplary embodiments presented here below.

Fig. 1 illustrates a cross-sectional view an embodiment of a medication delivery device 1. The medication delivery device 1 is in Fig. 1 illustrated in a starting condition before any medication is delivered. The medication delivery device 1 comprises an outer housing 20, which has a generally elongated shape. This type of medication delivery device is due to the shape often referred to as a pen-type injector.

A medication cartridge 10 is attached with a rear end 17 to a front end 22 of the outer housing 20. This attachment may be of different kinds, permanent or exchangeable. If the medication delivery device 1 is of a single use type, the attachment can be provided by a press fitting, an adhesive joint or attached permanently in any other manner. If the medication delivery device 1 is of a reusable type, the attachment has to be a removable one, e.g. by providing windings. The medication cartridge comprises in this embodiment a cartridge holder 12 in which a cartridge container 14 is accommodated. An inner volume 18 of the cartridge container 14 comprises the medication intended to be delivered. A stopper 16 is provided within the cartridge container 14, providing a sealing with the inner surfaces of the cartridge container 14. The stopper 16 is arranged movably in an axial direction A within the cartridge container 14. When originally provided, the stopper 16 is situated in level with the rear end 17 of the cartridge holder 12. During delivery of the medication, the stopper 16 is moved through the cartridge container 14, pushing the medication in front of it. The medication extracted by such a movement exits the cartridge container 14 at a front end 11 through a narrow hole. The front end of the cartridge holder 12 is provided with outer windings for enable attachment of a needle, through which the medication can be delivered. When the medication delivery device 1 is not used, the medication cartridge 10 can be sealed by attaching a cap onto the front end of the cartridge holder 12.

The medication delivery device 1 further comprises a piston rod 40. The piston rod is arranged along the axial direction A within the outer housing 20. A front end 41 of the piston rod 40 is arranged in mechanical contact with the stopper 16. In the present embodiment, the front end 41 presents a pin being provided in a turnable manner in a hole in a disc 42. The disc 42 is held against the outer surface of the stopper 16. In this manner, the piston rod can easily be turned without influencing the stopper 16. However, if the piston rod 40 is moved axially towards the front end, it will transfer a pushing force onto the stopper 16,

The piston rod 40 is provided with surface geometrical structures 43. Different part embodiments of such surface geometrical structures 43 will be discussed more in detail further below. The outer housing 20 has housing helical structures 24. The housing helical structures 24 spiral around the axial direction A and protrude radially inwards. In the present embodiments, the housing helical structures 24 are curved ridges protruding inwards from an inner surface of a hole in a disc shaped portion 23 of the outer housing 20. The hole is large enough to admit the piston rod 40 to be inserted there through. However, the surface geometrical structures 43 and the housing helical structures 24 are arranged for mechanically interact with each other. In the present embodiment, the curved ridges of the outer housing 20 will fit into the interspace between the surface geometrical structures 43 of the piston rod 40. This mechanical interaction between the surface geometrical structures 43 and the housing helical structures 24 thereby allows a movement, in the present disclosure called an extraction relative spiral movement, between the piston rod 40 and the outer housing 20. At the same time, the surface geometrical structures 43 and the housing helical structures 24 prohibit any other type of relative movements between the piston rod 40 and the outer housing 20. A restriction in the relative movements is thus provided. This means that if there is to be a relative movement between these two parts, it has to be the extraction relative spiral movement.

The medication delivery device 1 also comprises a dose drum 60. The dose drum 60 is arranged at least partially within the outer housing 20 and at least partially surrounding the piston rod 40. In other words, the dose drum 60 is provided in a space between, in a radial direction, the outer housing 20 and the piston rod 40. The dose drum 60 of the present embodiment is prohibited by the disc shaped portion 23 of the outer housing 20 to reach the medication cartridge 10 and the piston rod 40 therefore protrudes outside the dose drum 60 in the front side direction. However, in the present embodiment, a rear end 48 of the piston rod 40 is surrounded, at least in the radial direction, by the dose drum 60. Since the dose drum 60 and the piston rod 40 are movable relative to each other, the amount, by which the piston rod 40 is surrounded by the dose drum 60 will vary. The rear end 71 of the dose drum 60 protrudes in this embodiment outside the outer housing 20, while the front end 73 of the dose drum is kept between the outer housing 20 and the piston rod 40. During operation, the dose drum 60 and the outer housing 20 are movable relative to each other and also in this relation, the amount, by which the dose drum 60 is surrounded by the outer housing 20 will vary. The dose drum 60 comprises in its rear end 71 a dose knob 70. As will be further discussed further below, the dose knob 70 is the main means used during the setting of a medicament dose.

The dose drum 60 has dose drum helical structures 62. In the present embodiment, these dose drum helical structures 62 are provided as curved ridges and resemble the housing helical structures 24. The dose drum helical structures 62 spiral around the axial direction A and protrude radially inwards. As for the housing helical structures 24, the dose drum helical structures 62 are configured to mechanically interact with the surface geometrical structures 43 of the piston rod 40. This mechanical interaction allows for a relative movement between the dose drum 60 and the piston rod. This movement is in the present disclosure denoted as a dosing relative spiral movement between the piston rod 40 and the dose drum 60. In the present embodiment, the curved ridges of the dose drum 60 will fit into the interspace between the surface geometrical structures 43 of the piston rod 40. Also in this case, the surface geometrical structures 43 and the dose drum helical structures 62 prohibit any other type of relative movements between the piston rod 40 and the dose drum 60. This means that if there is to be a relative movement between these two parts, it has to be the dosing relative spiral movement. It is important however, to notice that the dosing relative spiral movement has an opposite spiral direction compared to the extraction relative spiral movement. In other words, they spiral in opposite directions. If the dosing relative spiral movement is counter-clockwise as seen from the rear end upon moving the piston rod 40 in the rear direction, the extraction relative spiral movement is instead clockwise when moving the piston rod 40 in the rear direction, or the opposite. The dosing relative spiral movement also has a steeper axial inclination than the extraction relative spiral movement. In other words, if turning the piston rod 40 one full turn relative to the outer housing 20, this will give rise to a relative axial movement that is smaller than a relative axial movement obtained after turning the piston rod 40 one full turn (in the opposite direction) relative to the dose drum 60. As will be discussed further below, this steeper axial inclination gives rise to a geared operation upon extraction of medication.

In the present embodiment, the dose drum 60 comprises at least one controllable rotation lock 66. In the present embodiment the controllable rotation lock 66 is a resilient portion 65 with a protruding tab 67, protruding in the radial direction out from the dose drum 60. Since the protruding tab 67 is provided at a resilient portion 65, the protruding tab 67 can easily be bent radially inwards if there is a free space inside the protruding tab 67. The outer housing 20 is provided with parallel grooves 25, directed axially in an inner surface of the outer housing 20. In other words, the parallel grooves 25 are facing the dose drum 60. The controllable rotation lock 66 is adapted in such a way that the protruding tab 67 of the controllable rotation lock 66 fits into one of the parallel grooves 25. A linear relative motion along the axial direction A between the dose drum 60 and the outer housing 20 is thus always allowed, since the protruding tab 67 slides within one of the parallel grooves 25. If a rotational force is applied between the dose drum 60 and the outer housing 20, the protruding tab 67 will be pushed back due to the resilient portion 65 by interaction with the ridges between the parallel grooves 25 if there is space available behind the protruding tab 67. When the protruding tab 67 passes into the next groove, the protruding tab 67 will spring back into the groove. This action will also give rise to an audible and tactile indication of a rotation associated with dose setting. This will be discussed further below. However, if the space behind the protruding tab 67 is occupied, the protruding tab 67 can not be removed elastically from the groove 25 and the mechanical interaction between the protruding tab 67 and the grooves 25 thereby prohibits any relative rotations. In other words, the dose drum 60 and the outer housing 20 are rotationally locked. As will be seen further below, a rotational locking between the dose drum 60 and the outer housing 20 is requested during the extraction phase. To this end, the medication delivery device 1 is equipped with a locking mechanism 80. The locking mechanism 80 is arranged for locking at least one portion of the dose drum 60 into one of said parallel grooves 25 of the outer housing 20. In the present embodiment, the locking mechanism 80 comprises a sliding drum 81. The sliding drum 81 is provided between the piston rod 40 and the dose drum 60. A rear end 82 of the sliding drum 81 protrudes through a hole 74 in the dose knob 70. The sliding drum 81 is prohibited to fall out from the dose knob 70 by protrusions 86 on the sliding drum 81 that are radially wider than the minimum size of the hole 74, in the present embodiment the size of the hole of an inner flange 76. The protrusions 86 are thus stopped by the inner flange 76. When no external force is applied on the rear end 82 of the sliding drum 81 , the sliding drum 81 is pressed against the inner flange 76 b a spring 72 provided in the dose knob 71.

In a relaxed state, a front end 84 of the sliding drum 81 is located just behind, in an axial direction, the protruding tab 67. In such a state, the sliding drum 81 does not prohibit any resilient action of the protruding tab 67. If the sliding drum 81 is pushed in the axial direction, e.g. by pressing the rear end 82 into the dose knob 70 against the action of the spring 72, the front end 84 of the sliding drum 81 is pushed into the space between the protruding tab 67 of the dose drum 60 and the piston rod 40. The protruding tab 67 is now locked against any motion radially inwards. The sliding drum 81 is thus arranged for prohibiting a resilient action of the resilient portion 65, when the sliding drum 81 is pushed in the axial direction.

In the present embodiment, the medication delivery device 1 is further provided with a window drum 90. The window drum 90 is provided inside a transparent cover part 21 of said outer housing 20 and around the dose drum 60. The window drum 90 is configured relative to the outer housing 20 for prohibiting the window drum 90 from performing major axial translations relative the outer housing 20. In the present embodiment, this is achieved by providing the window drum 90 between a rear end flange 26 of the outer housing 20 and an end cap 95 of the parallel grooves 25. The window drum 90 has interaction portions 96 that are arranged for providing a mechanical interaction with interaction portions 68 of an outer surface of the dose drum 60. In the present embodiment, the interaction portions 68 of an outer surface of the dose drum 60 are implemented as an outer spiral groove, and the interaction portions 96 of the window drum are implemented as spiraling ridges protruding radially inwards. This mechanical interaction allows a third relative spiral movement between the window drum 90 and the dose drum 60, but prohibits any other relative movements. An inclination and spiral direction of this third relative spiral movement is equal to the earlier discussed dosing relative spiral movement. This means that when the dose drum 60 is rotated relative both the piston rod 40 and the window drum 90, the piston rod 40 and window drum 90 presents the same relative axial movement relative to the dose drum 60. This in turn means that the distance between the window drum 90 and the piston rod 40 is unchanged during such movement. The dose drum 60 having dose markings provided at the outer surface of the dose drum 60. Such markings can in different embodiments be provided in the form of numbers, letters, scale markings, color markings or any other visible markings. The window drum 90 has a through opening 92, though which a part of these dose markings are viewable. The visible markings depends on the relative position between the window drum and the dose drum 60 and is intended for giving a user an indication of the size of the set dose.

As a summary of the allowed relative motions, the piston rod 40 is allowed to perform an extraction relative spiral movement relative to the outer housing 20 and a dosing relative spiral movement relative to the dose drum 60. The dosing relative spiral movement has a larger axial inclination than the extraction relative spiral movement and the movements are directed in opposite spiral direction. Furthermore, the dose drum 60 is allowed to perform an axial movement relative to the outer housing 20, but is prohibited from rotation movements relative to the outer housing 20 if the locking mechanism 80 is activated. These features together make it possible to provide an extraction operation which only uses linear movements of parts that can be exposed for the hands of the user.

Next, the operation of the medication delivery device will be described in connection with the Figures 1-5. As mentioned before, Fig. 1 illustrates the medication delivery device 1 in a state before any medication is delivered. The stopper 16 is in its original position and the dose drum 60 is pushed into its innermost position within the outer housing 20.

Fig. 2 illustrates the medication delivery device 1 in a state when an intended dose is set. The dose knob 70 is turned, i.e. rotated around the axial direction A. Due to the relative movement restriction between the piston rod 40 and the dose drum, the dose drum 60 moves out in the rear direction according to the dosing relative spiral movement. The locking mechanism 80 follows the dose drum 60. In the present embodiment, having the resilient portion 65, the rotation of the dose drum with respect to the outer housing will give rise to audible and tactile indications of the rotation, when the resilient portion moves between the different parallel grooves. Such rotation indications help typically the user to find an appropriate dose. The dose drum 60 is thus moved relative to the piston rod 40 a distance D. The window drum 90 is kept in the outer housing 20 and is also moved the distance D relative to the dose drum 60. A dose marking corresponding to the selected dose is now viewable through the window drum 90.

The window drum 90 prohibited from any substantial axial displacements relative to the outer housing 20 and the window drum 90 will due to the mechanical interaction with the dose drum ideally be kept unrotated in relation to the outer housing 20 during the turning of the dose knob 70. However, in a preferred embodiment, the window drum 90 is arranged to be in latching interaction with the outer housing 20 during spiral movement of the dose drum 60. The latching interaction is configured for counteracting a relative rotation between the window drum 90 and outer housing 20. In the present embodiment, this latching interaction is provided by a latching mechanism comprising teeth 97 at the rear end of the window drum 90. The teeth are directed in a rearwards axial direction. In alternative embodiment, the latching mechanism may be provided in a radial direction instead. The teeth 97 interact with flexible tongues 98 provided at the inside of the rear end flange 26. When a slight force, e.g. provided by the interaction with the dose drum 60, pushes the window drum against the rear end flange 26, the latching mechanism prohibits any rotation between the window drum 90 and the outer housing 20. When a minor force instead presses the window drum away from the rear end flange 26, a relative rotation between the outer housing and the window drum is allowed. This latching mechanism provides the advantage that the risk for the window drum 90 to be stuck between the dose drum 60 and the outer housing 20 is reduced significantly.

In Fig. 3, the extraction phase is begun. The locking mechanism 80 is activated. The sliding drum 81 is pushed into the dose knob 70. The front end 84 of the sliding drum 81 is then positioned inside the protruding tabs 67 on the dose drum 60 and prevents thereby the protruding tabs 67 to be bent out from the one of the parallel grooves 25 in which it is located. This restrict the dose drum 60 and outer housing 20 to perform only axial movements relative to each other. A relative movement of the dose drum 60 and the outer housing 20 results in a rotation of the window drum 90 relative to the outer housing 20.

In Fig. 4, the extraction has been performed. The user has pushed the dose knob 70 and the locking mechanism 80 linearly into the outer housing 20. Due to the activated locking mechanism 80, all parts that are exposed for potential contact with the user hand move purely linearly. Therefore, the dose drum 60 is moved axially into the outer housing, guided by the protruding tab 67 interacting with the parallel grooves 25. This mechanical interaction is maintained due to the position of the front end 84 of the sliding drum 81 supporting the protruding tab 67. When the dose drum 60 is moved linearly, the mechanical interaction with the piston rod 40, caused by the dose drum helical structures 62 and the surface geometrical structures 43 of the piston rod 40, causes the piston rod 40 to rotate. This rotation of the piston rod 40 takes place according to the dosing relative spiral movement.

A rotation of the piston rod 40 will in turn give rise to an axial movement of the piston rod 40 due to the mechanical interaction with the outer housing 20, which is held unrotated relative to the dose drum. The axial movement of the piston rod 40 is caused by the mechanical interaction between the surface geometrical structures 43 of the piston rod 40 and the housing helical structures 24 of the outer housing 20. The amount of axial displacement is determined by the allowed extraction relative spiral movement. Since the dosing relative spiral movement has a larger inclination than the extraction relative spiral movement, an axial displacement d of the front end 41 of the piston rod 40 becomes smaller than the distance D (of Fig. 2) by which the dose drum is moved. A gearing function is thus achieved.

The front end 41 of the piston rod 40 transfers a pushing force onto the stopper 16, which in turn in pushed into the cartridge container 14, extracting a dose of medication therefrom through the front end.

In Fig. 5, the locking mechanism 80 has been allowed to retract to its original inactivated position leaving a free space inside the protruding tab 67. The medication delivery device 1 is now ready for delivering a next dose of medicament. The only difference compared with Fig. 1 is that the stopper 16 is positioned deeper into the cartridge container 14, that the cartridge container 14 contains somewhat less medicament and that the piston rod 40 is displaced somewhat in the forward direction.

Some advantages with the present invention are obvious from the above description. All parts that can be contacted by the user hand are moving purely linearly during the extraction phase. At the same time, the pushing of the rear end of the medication delivery device is geared into a smaller extraction movement, which provides for higher extraction forces from a certain user pushing force.

In the particular embodiment discussed above, the configuration of the window drum 90 gives a user-friendly indication of the selected dose. Since the window drum 90 does not rotate during the setting of the dose, the opening 92 can all the time be facing the user, see Fig. 2. The exact dose markings can thereby easily be controlled by the user to get a fast and reliable setting of the dose to be extracted.

Fig. 6 illustrates an explosion view of the different parts of the embodiment of a medication delivery device according to the Figs. 1-5.

In the embodiment of a medication delivery device according to the Figs. 1-6, there are further details, which gives additional advantages for a user. In many prior art medication delivery devices, the remaining volume of medication in the cartridge container is typically judged by a visual inspection of the cartridge container through a transparent part of the cartridge holder. However, even if markings are provided on the cartridge container, it is often difficult for a user to know how to read the position of the stopper on such markings. To solve such problems, the present embodiment of a medication delivery device 1 involves a remaining dose indicator arrangement. With reference e.g. to Fig. 1 , a dose indicator 30 is axially movable and tangentially immovable in an indicator groove in the outer housing 20. The indicator 30 is visible in a window 29 in the outer housing 20. The dose indicator 30 is arranged for interacting with outer windings 64 of the dose drum 60. When the intended dose is set, by turning the dose drum 60, the dose drum 60 is turned also relative to the indicator 30, which then becomes axially translated with respect to the dose drum according to the outer windings 64. When the dose drum 60 is pushed back into the outer housing 20 upon extraction of the medicament, the indicator 30 is moved axially together with the dose drum 60. When the dose is extracted, the indicator 30 is again visible in the window 29, now moved somewhat axially compared with the original position, see Fig. 4 or 5. Remaining content markings can be easily adapted to reflect the remaining amount of medicament in the cartridge container, since the displacement is proportional to the displacement of the stopper 16.

Fig. 7 illustrates a side view of the medication delivery device 1 of Fig. 1 after a number of medicament extractions. The indicator 30 is seen through the window 29 and the position can easily be read relative a scale marking at the outside of the outer housing 20.

Fig. 8 shows a flow diagram of steps of an embodiment of a method for operating a medication delivery device. The method starts in step 200. In step 210, a dose drum is rotated in a dosing relative spiral movement relative a piston rod and a outer housing. The dose drum is locked from rotation relative to the outer housing in step 212. In step 214, all parts of the dose drum are pushed in a linear translation along an axial direction of the medication delivery device. The piston rod is in step 216 moved in an extraction relative spiral movement relative to the outer housing. This moving of the piston rod is performed by mechanical interactions between the piston rod and the outer housing and the dose drum, respectively. The moving is thereby indirectly caused by the pushing of the dose drum. The dosing relative spiral movement has an opposite spiral direction compared to the extraction relative spiral movement. The dosing relative spiral movement has furthermore a steeper axial inclination than said extraction relative spiral movement. In step 218, a stopper of a medication cartridge is translated in an axial direction within a cartridge container of the medication cartridge for extraction of medication from the medication cartridge. The stopper is arranged in mechanical contact with a front end of the piston rod for enabling transfer of a pushing force from the piston rod onto the stopper. The translating is thereby indirectly caused by the moving of the piston rod. The above presented embodiment of a medication delivery device has several advantages for a user of the medication delivery device. However, the above illustrated embodiment is also designed for enabling a cost-efficient manufacturing. The most cost-efficient manufacturing of the different parts of a medication delivery device is typically injection molding. A mold is injected with the material of the final product in a fluid form. The mold is removed after the material has solidified. In a most simple case, two mold halves can be used, removed from each other and the final product in opposite directions. When creating more complex structures, more than two mold parts may be necessary. For each additional mold part, the task of precision at mounting becomes more complex and the removal of the mold parts will also be more complex and time consuming. In particular when internal structures are created, the mold solutions are typically base on either collapsible units or mold cores that have to e.g. be screwed out from the final product. Such procedures are complex and costly. The design of the final product is therefore very crucial when discussing manufacturing costs.

The mechanical interaction between the piston rod and the dose drum and outer housing, respectively, can be provided in different manners. The most obvious way is to provide mutually engaging windings. In such a case, the piston rod has to present two outer windings, with different direction and different axial inclination. Furthermore, both the dose drum and the outer housing have to present inner windings. Such a solution will provide the advantages experienced by the user, as described above. With the above manufacturing methods in mind, one however realizes that both a double outer winding and inner windings are difficult to obtain by injection molding without complex arrangements and procedures or further machining. A complex arrangement or molding procedure or a further machining step induces higher manufacturing costs.

In a preferred embodiment, the details for the mechanical interaction with the piston rod are designed in such a way that only injection molding without any following machining step can be used. First, the housing helical structures 24 of the outer housing 20 can be designed for totally covering at the most one full turn. Another way to express this is that the housing helical structures 24 do not overlap when they are being viewed in the axial direction. If this is true, a mold can be opened at the housing helical j structure in two opposite direction. This can be realized e.g. by a single winding covering at the most one full turn around the inner surface. This is schematically illustrated in Fig. 9A. An alternative way is to provide two parallel windings, each one covering at the most one half turn. This is schematically illustrated in Fig. 9B. Such structures can be manufactured

) by injection molding with mold parts that are removed from each other in a pure axial direction.

Secondly, the dose drum helical structures 62 can be designed in a similar manner, for totally covering at the most one full turn. Another way to

> express this is that the dose drum helical structures 62 do not overlap when being viewed in the axial direction. This can analogously with earlier description be realized e.g. by a single winding covering at the most one full turn around the inner surface. This is schematically illustrated in Fig. 9C. An alternative way is to provide two parallel windings, each one covering at

) the most one half turn. This is schematically illustrated in Fig. 9D.

Also the piston rod can be designed for simplifying for injection molding. The surface geometrical structures 43 of the piston rod 40 can be provided as protruding stubs 44, as illustrated in Fig. 10A. By providing such protruding i stubs, e.g. in rows along the axial direction with appropriate axial distances between the stubs, the same type of mechanical interaction between piston rod and the dose drum and outer housing, respectively, can be obtained, as by using ordinary windings. In different embodiments of a piston rod, each individual one of the protruding stubs 44 protrudes either in a first direction

I 100, perpendicular to the axial direction A, or a second direction 101 opposite to the first direction 100. In the illustrated embodiment of Fig. 10A, half of the protruding stubs 44 protrude in the first direction 100 and the remaining half of the protruding stubs 44 protrude in the second direction. An injection mold can thereby be designed in two halves having a connection line at the middle of the piston rod 40 as indicated by the broken line 102. The mold can thereby be opened and the two mold halves can be removed from the piston rod in opposite direction. In the embodiment of Fig. 10A, the protruding stubs 44 are provided in four rows along the axial direction A with an equal pitch P within each row. However, the position pattern of the protruding stubs can be designed in many different ways. As long as the protruding stubs 44 leave one spiral path in one direction and another spiral path open in the other direction (preferably with a different inclination), and the distance between such open paths and a closest protruding stub 44 is small compared to the inclination, the mechanical interaction with a winding-like counterpart can be established.

In alternative embodiments, the protruding stubs 44 are provided only in one direction, i.e. either in the first direction 100 or the second direction 101 , as illustrated in Fig. 10B.

An example of an embodiment of a piston rod with a different pattern of protruding stubs 44 is illustrated. Here two rows of stubs are provided at one side, while the opposite side has one row. The two row of the first side have furthermore different pitches. In further alternative embodiments, the protruding stubs 44 may also be provided in irregular patterns, both in axial and radial directions.

The details of the different parts of embodiments of a medication delivery device according to the present may differ within the knowledge of anyone skilled in the art. As long as the interaction between the different parts provides the requested relative movement patterns, the exact design is generally not as important, except where the design may facilitate the manufacturing principles, as was discussed above. The technical effects concerning the user operation advantages are typically provided as long as the relative movement principles are achieved. In preferred embodiments, a region with parts of the surface geometrical structures that causes the dosing relative spiral movement overlaps with a region with parts of the surface geometrical structures that causes the extraction relative spiral movement, as seen in an axial direction. In other words, the surface geometrical structures provide for a double threading mechanism in association with the helical structures. This double threading preferably extends over a major part of the region of the surface geometrical structures, and typically over the entire region of the surface geometrical structures. This can also be expressed as that the active lengths of the structures causing the two different movements are overlapping to a large extent. The region of the surface geometrical structure does also preferably extend over a majority of the length of the piston rod. The piston rod can thereby be used for causing relative motions with long strokes, also with parts with limited extension in the axial direction, e.g. the helical structures.

An example of a detail, which can be designed in many different ways is the locking mechanism and the parts providing the controllable locking between the dose drum and the outer housing. Figs. 11A-B illustrates schematically another solution. In this embodiment, a pivotable member 77 is provided at the dose drum 60, which is pivotable around an axis 75. The front end 84 of the sliding drum 81 of the locking mechanism 80 reaches in this embodiment a position inside the axis 75 in the inactivated state, as illustrated in Fig. 1 1A. When activating the locking mechanism 80, the sliding drum 81 is pushed in the axial direction. The front end 84 of the sliding drum 81 pushes a protruding part 79 of the pivotable member 77, causing the pivotable member 77 to pivot around the axis 75. An outer edge 78 of the pivotable member 77 is then brought into one of the parallel grooves 25 of the outer housing 20, resulting in a locking against relative rotations. This is only one example of possible alternative embodiments of part solution which will provide the same technical effect as was described further above. For instance, the locking mechanism may not necessarily comprise a sliding drum. Other types of parts that are possible to position by a movement in the axial direction can also be used for controlling the rotational locking between the dose drum and the outer housing, such as e.g. different types of bars.

Another embodiment of a medication delivery device 1 is illustrated in a cross-sectional view in Fig. 12. Many parts are similar to the ones presented in the previous embodiments and will not be discussed again. In the embodiment of Fig. 12, the dose indicator is omitted, however, as anyone skilled in the art realizes, in an alternative embodiment, a dose indicator can be provided, e.g. according to the previously described principles.

The main difference between the embodiment of Fig. 12 and previous embodiments is the design of the dose knob 70. In the present embodiment, the dose knob 70 is attached to the rear end 82 of the sliding drum. The dose knob 70 is still the main means used during the setting of a medicament dose. In another view, the dose knob 70 of the present embodiment can be viewed as an expanded rear end 82 of the sliding drum.

Fig. 13 illustrates the embodiment of a medication delivery device 1 of Fig. 12 in a state when an intended dose is set. The dose knob 70 is turned, i.e. rotated around the axial direction A. The sliding drum and the dose drum 60 are in frictional contact with each other along a relatively long section. The friction between the sliding drum and the dose drum 60 can further be increased e.g. by introducing high-viscosity grease in the slit between them. A gentle rotating force on the dose knob 70 will thereby be transferred to the dose drum, which follows in the rotation. As before, due to the relative movement restriction between the piston rod 40 and the dose drum, the dose drum 60 moves out in the rear direction according to the dosing relative spiral movement. The dose drum 60 is thus moved relative to the piston rod 40 a distance D. The window drum 90 is kept in the outer housing 20 and is also moved the distance D relative to the dose drum 60.

In Fig. 14, the extraction phase has begun. The locking mechanism 80 is activated. The dose knob 70 is pushed axially causing the sliding drum to move relative to the dose drum 60 until a lower portion of the dose knob 70 reaches the upper part of the dose drum 60. This relative movement also causes the front end 84 of the sliding drum to be positioned inside the protruding tabs 67 on the dose drum 60 and prevents thereby the protruding tabs 67 to be bent out from the one of the parallel grooves 25 in which it is located. This restricts the dose drum 60 and outer housing 20 to perform only axial movements relative to each other. A relative movement of the dose drum 60 and the outer housing 20 results in a rotation of the window drum 90 relative to the outer housing 20. A further pushing of the dose knob 70 in an axial direction causes the piston rod to move down axially and extrude a dose from the cartridge container 14 as described in earlier embodiments.

The embodiments described above are to be understood as a few illustrative examples of the present invention. It will be understood by those skilled in the art that various modifications, combinations and changes may be made to the embodiments without departing from the scope of the present invention. In particular, different part solutions in the different embodiments can be combined in other configurations, where technically possible. The scope of the present invention is, however, defined by the appended claims.

Figure references:

I medication delivery device

10 medication cartridge

I I front end of cartridge holder

12 cartridge holder

14 cartridge container

16 stopper

17 rear end of cartridge holder

18 inner volume of medication container

20 outer housing

21 transparent cover part

22 front end of outer housing

23 disc shaped portion of outer housing

24 housing helical structures

25 parallel grooves in outer housing

26 rear end flange of outer housing

29 window in outer housing

30 indicator

40 piston rod

41 front end of piston rod

42 disc

43 surface geometrical structures

44 protruding stubs

60 dose drum

62 dose drum helical structures

64 outer windings of dose drum

65 resilient portion of dose drum

66 controllable rotation lock

67 protruding tab

68 interaction portion of outer surface of dose drum

70 dose knob

71 rear end of dose drum

72 spring 73 front end of dose drum

74 hole in dose knob

75 pivot axis

76 inner flange of dose knob

77 pivotable member

78 outer edge

79 protruding part

80 locking mechanism

81 sliding drum

82 rear end of sliding drum

84 front end of sliding drum

86 protrusions on sliding drum

90 window drum

92 through opening in window drum

95 end cap of parallel grooves

96 interaction portion of window drum

97 teeth

98 flexible tongues

A axial direction

D dose setting distance

P pitch of stub row

100 first direction

101 second direction

102 separation line for mold

103 piston rod middle

210-218 Method steps

Claims

1. A medication delivery device (1), comprising:

- an outer housing (20), having a generally elongated shape;

- a medication cartridge (10) attached to a front end (22) of said outer housing (20);

said medication cartridge (10) having a cartridge holder (12), a cartridge container (14) and a stopper (16), said stopper (16) being arranged movably in an axial direction (A) within said cartridge container (14) for extraction of medication from said medication cartridge container (14);

- a piston rod (40) arranged along said axial direction (A) within said outer housing (20);

a front end (41) of said piston rod (40) being arranged in mechanical contact with said stopper (16) for enabling transfer of a pushing force from said piston rod (40) onto said stopper (16);

said outer housing (20) having housing helical structures (24), said housing helical structures (24) spiral around said axial direction (A) and protrude radially inwards;

said piston rod (40) having surface geometrical structures (43), arranged for mechanically interact with said housing helical structures (24), said mechanical interaction between said surface geometrical structures (43) and said housing helical structures (24) allowing an extraction relative spiral movement between said piston rod (40) and said outer housing (20);

- a dose drum (60), arranged at least partially within said outer housing (20) and at least partially surrounding said piston rod (40);

said dose drum (60) having dose drum helical structures (62), said dose drum helical structures (62) spiral around said axial direction (A) and protrude radially inwards, said dose drum helical structures (62) being configured for mechanically interacting with said surface geometrical structures (43) of said piston rod (40), allowing a dosing relative spiral movement between said piston rod (40) and said dose drum (60);

said dosing relative spiral movement having an opposite spiral direction compared to said extraction relative spiral movement; said dosing relative spiral movement having a steeper axial inclination than said extraction relative spiral movement;

said outer housing (20) having parallel grooves (25), directed axially in an inner surface of said outer housing (20); and

- a locking mechanism (80) arranged for locking at least one portion of said dose drum (60) into one of said parallel grooves (25) of said outer housing (20).

2. The medication delivery device according to claim 1 , characterized by further comprising:

- a window drum (90) provided inside a transparent cover part (21) of said outer housing (20);

said window drum (90) being configured relative to said outer housing (20) for prohibiting said window drum (90) from performing major axial translations relative said outer housing (20);

said window drum (90) having interaction portions (96) being arranged for providing a mechanical interaction with interaction portions (68) of an outer surface of said dose drum (60), said mechanical interaction allowing a third relative spiral movement between said window drum (90) and said dose drum (60);

an inclination and spiral direction of said third relative spiral movement being equal to said dosing relative spiral movement;

said window drum (90) being arranged to be in latching interaction with said outer housing (20) during spiral movement of said dose drum (60), said latching interaction being configured for counteracting a relative rotation between said window drum (90) and said outer housing (20);

said dose drum (60) having dose markings provided at said outer surface of said dose drum (60);

said window drum (90) having a through opening (92), though which a part of said dose markings are viewable.

3. The medication delivery device according to claim 1 or 2, characterized in that said dose drum (60) comprises a resilient portion (65) provided into said parallel grooves (25) of said outer housing (20), and in that said locking mechanism (80) comprises a sliding drum (81) provided between said piston rod (40) and said dose drum (60), said sliding drum (81) being arranged for prohibiting a resilient action of said resilient portion (65) when pushed forward in said axial direction (A).

4. The medication delivery device according to any of the claims 1 to 3, characterized in that said housing helical structures (24) do not overlap when being viewed in said axial direction (A) .

5. The medication delivery device according to any of the claims 1 to 4, characterized in that said dose drum helical structures (62) do not overlap when being viewed in said axial direction (A).

6. The medication delivery device according to any of the claims 1 to 5, characterized in that a region with parts of said surface geometrical structures (43) causing said dosing relative spiral movement overlaps to a major part, in an axial direction, with a region with parts of said surface geometrical structures (43) causing said extraction relative spiral movement.

7. The medication delivery device according to any of the claims 1 to 6, characterized in that said surface geometrical structures (43) are protruding stubs (44).

8. The medication delivery device according to claim 7, characterized in that each individual one of said protruding stubs (44) protrudes either in a first direction (100), perpendicular to said axial direction (A), or a second direction (101) opposite to said first direction (100).

9. The medication delivery device according to claim 7 or 8, characterized in that said protruding stubs (44) are provided in four rows along said axial direction (A) with an equal pitch (P) within each row.

10. The medication delivery device according to any of the claims 1 to 9, characterized by further comprising:

- a dose indicator (30), arranged axially movable and tangentially immovable in an indicator groove in said outer housing (20);

said dose indicator (30) being arranged for interacting with outer windings (64) of said dose drum (60) .

1 1. Method for operating a medication delivery device, comprising the steps of:

rotating (210) a dose drum in a dosing relative spiral movement relative a piston rod and an outer housing;

locking (212) said dose drum from rotation relative to said outer housing;

pushing (214) all parts of said dose drum in a linear translation along an axial direction of said medication delivery device;

moving (216) said piston rod in an extraction relative spiral movement relative to said outer housing, said step of moving said piston rod being performed by mechanical interactions between said piston rod and said outer housing and said dose drum, respectively, thereby caused by said pushing (214) of said dose drum;

said dosing relative spiral movement having an opposite spiral direction compared to said extraction relative spiral movement;

said dosing relative spiral movement having a steeper axial inclination than said extraction relative spiral movement;

translating (218) a stopper of a medication cartridge in an axial direction within a cartridge container of said medication cartridge for extraction of medication from said medication cartridge, said stopper being arranged in mechanical contact with a front end of said piston rod for enabling transfer of a pushing force from said piston rod onto said stopper, said step of translating thereby being caused by said step of moving (216) said piston rod.