WO2020193100A1

WO2020193100A1 - A shielded medical injection device with a cleaning reservoir

Info

Publication number: WO2020193100A1
Application number: PCT/EP2020/055923
Authority: WO
Inventors: Simon Munch Pedersen
Original assignee: Novo Nordisk A/S
Priority date: 2019-03-26
Filing date: 2020-03-05
Publication date: 2020-10-01

Abstract

The invention relates to an injection device, preferably of the pre-filled type. The injection de- vice comprises a housing structure which supports a piston rod drive for driving a preservative containing pharmaceutical liquid drug out from a cartridge which is axially movable a small distance in relation to the housing structure. The injection device further comprises a movable needle hub securing a needle cannula and a rotatable needle shield covering the needle cannula. The needle hub is movable in a proximal direction to insert the proximal part of the needle cannula through the pierceable septum and into the interior of the cartridge, and the needle shield which carries a cleaning reservoir containing a predetermined volume of the preservative containing pharmaceutical liquid drug for cleaning at least the distal tip of the needle cannula between subsequent injections, is rotatable from a first position to a second position. Further, transfer means are provided which transfers axial and linear movement of the needle hub to a helical movement of a transfer element which moves the cartridge proximally relatively to the housing structure to thereby force liquid preservative containing drug from the interior of the cartridge through the lumen of the needle cannula and into the cleaning reservoir.

Description

A Shielded Medical Injection Device with a Cleaning Reservoir

THE TECHNICAL FIELD OF THE INVENTION:

The invention relates to a pre-filled injection device for injecting a liquid pharmaceutical drug, and preferably for injecting a plurality of individually settable doses of the liquid pharmaceuti cal drug. The invention especially relates to such pre-filled injection devices wherein the same needle cannula is used for multiple injections and wherein the skin penetrating tip of the needle cannula is cleaned between subsequent injections. To clean the skin penetrating end of the needle cannula between injections, the invention further relates to a cleaning res ervoir containing a volume of the same preservative containing liquid pharmaceutical drug as contained in the injection device such that the preservative contained in the liquid pharma ceutical drug works as a cleaning agent.

DESCRIPTION OF RELATED ART:

An injection device wherein a needle shield carries a cleaning reservoir containing a volume of the same preservative containing liquid pharmaceutical drug as contained in the injection device is disclosed in WO 2016/173895. The volume of the preservative containing liquid pharmaceutical drug contained in the cleaning reservoir functions as a cleaning solvent for keeping the distal tip of the needle cannula biological clean between subsequent injections.

In this type of injection devices, the user is required to transfer a small volume of the pre servative containing liquid pharmaceutical drug from the container of the injection device and into the cleaning reservoir before taking the first injection. This process of transferring the liquid drug is often referred to as initiating the injection device i.e. making the injection device ready to be used for injecting.

During initiation of the injection device disclosed in WO 2016/173895, the cartridge is pushed a distance of a few millimetres in the proximal direction as indicated by the“X” in figure 16A of WO 2016/173895. At the same time, the piston rod drive system prevents the piston rod and thus the plunger inside the cartridge from moving in the proximal direction. The result of moving the glass part of the cartridge while maintaining the position of the piston rod and the plunger is that the pressure inside the cartridge is increased which forces a volume of the liquid drug to flow through the lumen of the needle cannula and into the hollow cleaning res ervoir.

As disclosed in WO 2016/173895, the user rotates the needle shield in order to initiate the injection device. The rotation of the needle shield is transferred to a similar rotation of the needle hub. The needle hub is further connected to a transfer element such that the transfer element rotates together with the needle hub at least during a part of the rotational move ment of the needle hub. The transfer element is proximally engaged with the housing struc ture such that rotation of the transfer element moves the transfer element helically in the proximal direction along a ramp (reference No. 187B in figure 10 of WO 2016/173895). Through a simple abutment of the transfer element and the cartridge, the cartridge or rather the glass part of the cartridge is forced to move in the proximal direction together with the transfer element which increases the pressure inside the cartridge.

However, rotation of the needle hub during initiation has the drawback that the needle cannu la is also rotated while it is moved through the septum of the cartridge which potentially cuts into the septum and thus obstructs the ability of the septum material to seal properly after being penetrated.

Another solution is disclosed in WO 2019/238,806. This PCT application discloses a needle hub which is guided strictly axially (i.e. translational) in the housing structure upon rotation of the needle shield to thereby secure a prober penetration of the septum of the cartridge. The strictly axial movement of the needle hub is further transferred to an axial movement of a transfer element (reference No. 85 in figure 3 of WO 2019/238,806) which simultaneously pushes the glass part of the cartridge axially in the proximal direction.

However, when the transfer element is moved purely axially it is difficult to control the trans fer movement and especially the stopping point of the movement due to the tolerances of the polymer parts making up the injection device. It is thus difficult to obtain full control of the car tridge movement and specially to control how far the cartridge is moved in the proximal direc tion.

DESCRIPTION OF THE INVENTION: It is henceforth an object of the present invention to provide a solution in which the cartridge is moved in the proximal direction under full control and without the before mentioned draw backs.

Accordingly, in one aspect of the present invention, a pre-filled injection device with a piston rod drive system for delivering doses a preservative containing pharmaceutical liquid drug is provided. This injection device comprises a plurality of structural components which are de fined in the following:

- A housing structure which supports the piston rod drive system and the non- replaceable cartridge. The cartridge is axially movable a small distance in relation to the housing structure. o The cartridge comprises a pierceable septum at a distal end and a movable plunger at the opposite proximal end. The interior contains a preservative con taining pharmaceutical liquid drug and the movable plunger inside the car tridge has a proximal surface abutting the piston rod drive system. o The piston rod drive system for moving the movable plunger in the distal direc tion inside the cartridge during dosing and the movable plunger inside the car tridge is prevented from movement in the proximal direction e.g. by a one-way ratchet or the like.

- A needle hub securing a needle cannula. o The needle cannula has a distal part with a distal tip for piercing the skin of a user during injection and an opposite proximal part and a lumen there be tween. o The needle hub is movable in a proximal direction to insert the proximal part of the needle cannula through the pierceable septum of the cartridge such that the lumen of the needle cannula connects to the interior of the cartridge.

A needle shield rotatable relatively to the housing structure from a first position to a second position. o The needle shield carries a cleaning reservoir preferably at a distal end which cleaning reservoir contains a volume of the preservative containing pharma ceutical liquid drug when filled, for cleaning at least the distal tip of the needle cannula between subsequent injections. o Rotation of the needle shield from the first position to the second position is transformed to a movement of the needle hub in the proximal direction.

- A transfer arrangement for transferring movement of the needle hub in the proximal direction to a movement of the cartridge in the proximal direction,

According to the present invention, the needle hub is guided translationally (i.e. without rota tion) in relation to the housing structure when the needle hub is moved proximally, and the transfer arrangement comprises a transfer element for operating the cartridge. Further, the transfer element engages the needle hub such that the axially guided movement of the nee dle hub in the proximal direction is transferred to a helical movement of the transfer element in the proximal direction whereby the transfer element abuts and moves the cartridge proxi mally relatively to the housing structure to thereby force liquid preservative containing drug from the interior of the cartridge through the lumen of the needle cannula and into the clean ing reservoir.

Rotation of the needle shield is thus transferred to a purely axial (i.e. translational) movement of the needle hub as the needle hub is guided axially in relation to the housing structure and the axial movement of the needle hub is transferred to a helical rotation of the transfer ele ment.

The user henceforth just has to rotate the needle shield e.g. by assistance from the protec tive cap which will result in a rotational and helical movement of the transfer element.

Since the transfer element abuts and moves the cartridge, the cartridge is moved in the prox imal direction by the helical movement of the transfer element.

As the piston rod drive system prevents the plunger inside the cartridge in moving in the proximal direction only the outer part of the cartridge moves proximally which henceforth builds up a pressure inside the interior of the cartridge which overpressure forces a volume of the preservative containing pharmaceutical liquid drug to flow through the lumen of the needle cannula and into the cleaning reservoir carried by the needle shield. Once the clean ing reservoir has been filed, the initiation process is over, and the volume contained in the cleaning reservoir operates as a cleaning solvent which keeps the distal tip of the needle cannula clean between subsequent injections.

By rotating the transfer element which transfers axial translation of the needle hub to the car tridge a better control of the axial movement is obtained.

In its most simple form the transfer element can be threaded to the housing structure or at least to a part of the housing structure such that the transfer element is screwed helically when rotated.

The axial guidance of the needle hub in relation to the housing structure is preferably done by providing an axial guiding structure between the needle hub and the housing structure.

In one example the housing structure comprises a cartridge holder part for securing the car tridge and which cartridge holder part comprises the axial guiding means for guiding the needle hub axially.

In one example, these axial guiding means are axial track structures such as axial rails pro vided in the cartridge holder part guiding a number of guiding arms or the like provided on the hub.

Further, the axially guided needle hub and the transfer element are provided with engaging means for transforming the purely axial movement of the needle hub to a rotation of the transfer element.

In one example, these engaging means comprises a protrusion engaging a track. Preferably, the transfer element carries the protrusion and the needle hub carries the track however the opposite is also an option. The axial translation of the needle hub thus forces the protrusion and henceforth the transfer element to follow the track provided in the needle hub. In a preferred example the track provided in the needle hub has a sloped configuration such that the protrusion and the transfer element are forced to rotate relatively to each other along the sloped configuration as the needle hub is moved in its axially guided translational move ment. Henceforth, a purely axial translation of the needle hub is transformed to a rotation of the transfer element via the engagement between the protrusion and the sloped track.

In a different example, the engaging means which transfers the purely axially guided move ment of the needle hub to a rotation of the transfer element comprises an axial wing for mation and an opening.

Preferably, the transfer element carries the axial wing and the needle hub carries the open ing. The axial wing is preferably provided with a sloped surface such that when the needle hub is guided translationally in relation to the transfer element, the transfer element is forced to rotate as the sloped surface on the wing formation abuts the opening in the needle hub.

All though the engagement means between the needle hub and the transfer element is ex plained as either an engagement between a protrusion on the transfer element and a sloped surface in the needle hub or an engagement between an axial wing on the transfer element and an opening in the needle hub, the engagement means could be any combination of the two or either of the two alone. Further, kinematic reversal is possible such that the means responsible for the engagement can be provided on the opposite element.

One way of turning the rotational movement of the transfer element into a helical movement of the transfer element is to provide abutment means between the housing structure and the transfer element which moves the transfer element axially when the housing structure and the transfer element are rotated relatively to each other. These abutments means thus oper ates as a thread segment such that the transfer element is moved axially when rotated. Al ternatively, a purely threaded connection can be provided.

In one example, the abutment means comprises a knob preferably provided on the transfer element and a sloped surface preferably provided on the housing structure. In a preferred example, the knop extends in a radial outwardly pointing direction on the trans fer element and the sloped surface is provided on an inwardly pointing part of the cartridge holder part of the housing structure.

Further, the needle shield is prevented from translating axially when in the first position but is allowed to translate axially in relation to the housing structure when in the second position.

The first position of the needle shield is thus the position in which the injection device is initi ated and made ready for injection and the second position of the needle shield is the position in which an injection can actually be performed.

Henceforth in the first position it is possible for the user to rotate the needle shield and in the second position it is possible to slide the needle shield axially.

In a further example, the needle shield is helically movable in relation to the housing struc ture in the first position. During rotation, the needle shield thus moves helically in the proxi mal direction at least during a part of the rotation of the needle shield.

DEFINITIONS:

An“injection pen” is typically an injection apparatus having an oblong or elongated shape somewhat like a fountain pen for writing. Although such pens usually have a tubular cross- section, they could easily have a different cross-section such as triangular, rectangular or square or any variation around these geometries.

The term“Needle Cannula” is used to describe the actual conduit performing the penetra tion of the skin during injection. A needle cannula is usually made from a metallic material such as e.g. stainless steel and preferably connected to a hub made from a suitable material e.g. a polymer. A needle cannula could however also be made from a polymeric material or a glass material.

As used herein, the term“Liquid drug” is meant to encompass any drug-containing flowa- ble medicine capable of being passed through a delivery means such as a hollow needle cannula in a controlled manner, such as a liquid, solution, gel or fine suspension. Repre sentative drugs include pharmaceuticals such as peptides, proteins (e.g. insulin, insulin ana- logues and C-peptide), and hormones, biologically derived or active agents, hormonal and gene based agents, nutritional formulas and other substances in both solid (dispensed) or liquid form.

The term“preservative containing liquid drug” is preferably used to describe a liquid drug containing any kind of preservative. Such liquid drug could in one example be a blood sugar regulating liquid drug such as insulin, insulin analogue, GLP-1 or GLP-2, and the preserva tive contained in the liquid drug could in one example be phenol, meta-cresol or any combi nation thereof. However, any kind of preservative can under this term be combined with any kind of liquid drug.

“Cartridge” is the term used to describe the container actually containing the drug. Cartridg es are usually made from glass but could also be moulded from any suitable polymer. A car tridge or ampoule is preferably sealed at one end by a pierceable membrane referred to as the“septum” which can be pierced e.g. by the non-patient end of a needle cannula. Such septum is usually self-sealing which means that the opening created during penetration seals automatically by the inherent resiliency once the needle cannula is removed from the sep tum. The opposite end of the cartridge is typically closed by a plunger or piston made from rubber or a suitable polymer. The plunger or piston can be slidable moved inside the car tridge. The space between the pierceable membrane and the movable plunger holds the drug which is pressed out as the plunger decreased the volume of the space holding the drug.

The cartridges used for both pre-filled injection devices and for durable injections devices are typically factory filled by the manufacturer with a predetermined volume of a liquid drug. A large number of the cartridges currently available contains either 1 ,5 ml or 3 ml of liquid drug.

Since a cartridge usually has a narrower distal neck portion into which the plunger cannot be moved not all of the liquid drug contained inside the cartridge can actually be expelled. The term“initial quantum” or“substantially used” therefore refers to the injectable content contained in the cartridge and thus not necessarily to the entire content.

“Cleaning chamber or reservoir” is in the present description broadly meant to be any kind of reservoir containing a cleaning solvent to clean at least the distal tip of the needle cannula between subsequent injections. Such cleaning chamber is preferably both distally and proxi- mally sealed by a pierceable septum or the like. However, the proximal septum could be re- placed by any kind of sealing which would seal against the outer surface of the needle can nula e.g. a movable plunger with some kind of sealing. The distal septum and the proximal septum or seal of the cleaning chamber defines a confinement containing the cleaning sol vent which cleaning solvent in a preferred embodiment is identical to the preservative con tained in the liquid drug used in the specific injection device. In a most preferred solution, the same preservative containing liquid drug is present both in the cleaning chamber and in the cartridge of the injection device thereby avoiding contamination of the preservative contain ing drug inside the cartridge.

By the term“Pre-filled” injection device is meant an injection device in which the cartridge containing the liquid drug is permanently embedded in the injection device such that it cannot be removed without permanent destruction of the injection device. Once the pre-filled amount of liquid drug in the cartridge is used, the user normally discards the entire injection device. Usually the cartridge which has been filled by the manufacturer with a specific amount of liq uid drug is secured in a cartridge holder which is then permanently connected in a housing structure such that the cartridge cannot be exchanged.

This is in opposition to a“Durable” injection device in which the user can himself change the cartridge containing the liquid drug whenever it is empty. Pre-filled injection devices are usu ally sold in packages containing more than one injection device whereas durable injection devices are usually sold one at a time. When using pre-filled injection devices an average user might require as many as 50 to 100 injection devices per year whereas when using du rable injection devices one single injection device could last for several years, however, the average user would require 50 to 100 new cartridges per year.

“Scale drum” is meant to be a preferably cylinder shaped element carrying indicia indicating the size of the selected dose to the user of the injection device. The cylinder shaped element making up the scale drum can either be solid or hollow.“Indicia” is meant to incorporate any kind of printing or otherwise provided symbols e.g. engraved or adhered symbols. These symbols are preferably, but not exclusively, Arabian numbers from“0” to“9”. In a different example, alphabetic letters from any alphabet available can be used. However, the symbols can also be graphical pictures indicating a specific situation or specific use such symbols could e.g. be a key, a lock, a drop or similar symbol which provides the user information re lating to the use of the injection device. In a traditional pen configuration the indicia is viewa ble through a window or opening provided in the housing structure. Using the term“Automatic” in conjunction with injection device means that, the injection device is able to perform the injection without the user of the injection device delivering the force needed to expel the drug during dosing. The force is typically delivered - automatically

- by an electric motor or by a spring drive. The spring for the spring drive is usually strained by the user during dose setting, however, such springs are usually prestrained in order to avoid problems of delivering very small doses. Alternatively, the spring can be fully preloaded by the manufacturer with a preload sufficient to empty the entire drug cartridge though a number of doses. Typically, the user activates a latch mechanism provided either on the sur face of the housing or at the proximal end of the injection device to release - fully or partially

- the force accumulated in the spring when carrying out the injection.

The term“Permanently connected” or“permanently embedded” as used in this descrip tion is intended to mean that the parts, which in this application is embodied as a cartridge permanently embedded in the housing, requires the use of tools in order to be separated and should the parts be separated it would permanently damage at least one of the parts.

The term“protective cap” is herein meant to refer to a cover or a sleeve-like structure which is mounted at the distal end of the injection device between injections. Such cover or sleeve-like structure is usually closed at the distal end to fully encapsulate the distal part fo the injection device. The protective cap is hence secured to the distal end of the injection de vice and protects the distal end of the injection device between injections. Should a needle cannula be mounted to the distal end of the injection device, either permanently or ex changeable, such needle cannula is henceforth also protected by the protective cap. Since the protective cap is mounted each time an injection has been performed, the word“re mounted” can also be used to describe the mounting of the protective cap. Further, since the housing structure of an injection device often has a window through which the user can visu ally inspect the liquid drug, the protective cap also serves to protect the liquid drug from long time exposure to light as some liquid drugs are sensitive to light, especially in the UV range.

All references, including publications, patent applications, and patents, cited herein are in corporated by reference in their entirety and to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. All headings and sub-headings are used herein for convenience only and should not be con structed as limiting the invention in any way.

The use of any and all examples, or exemplary language (e.g. such as) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be con strued as indicating any non-claimed element as essential to the practice of the invention. The citation and incorporation of patent documents herein is done for convenience only and does not reflect any view of the validity, patentability, and/or enforceability of such patent documents.

This invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law.

BRIEF DESCRIPTION OF THE DRAWINGS:

The invention will be explained more fully below in connection with a preferred embodiment and with reference to the drawings in which:

Figure 1 show a perspective view of the injection device with the protective cap at- tached.

Figure 2 show a perspective view of the injection device with the protective cap re moved.

Figure 3 show an exploded view of the housing structure.

Figure 4 show an exploded view of the front-end of the injection device.

Figure 5 show a cross-sectional view of the front-end of the injection device.

Figure 6 show a cross-sectional view of the needle shield.

Figure 7 show two cross-sectional views of the protective cap.

Figure 8A show a side view of the transfer element. Figure 8B show an end view along the line A-A of figure 8A. Figure 8C-D show two different perspective views of the transfer element. Figure 9A-B show two different side views of the needle hub. Figure 9C show an end view along the line B-B of figure 9A. Figure 10 show an exploded view of the cartridge holder part, the transfer element and the needle hub.

Figure 1 1A-G shows the position of the transfer element in relation to the cartridge holder part in the various states.

Figure 12A-G shows the position of the needle hub in relation to the cartridge holder in the various states.

Figure 13 shows a further view of the needle hub and the cartridge holder in state 4 of figure 1 1 D and 12D.

The figures are schematic and simplified for clarity, and they just show details, which are es sential to the understanding of the invention, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts.

DETAILED DESCRIPTION OF EMBODIMENT:

When in the following terms as“upper” and“lower”,“right” and“left”,“horizontal” and“verti cal”,“clockwise” and“counter clockwise” or similar relative expressions are used, these only refer to the appended figures and not to an actual situation of use. The shown figures are schematic representations for which reason the configuration of the different structures as well as their relative dimensions are intended to serve illustrative purposes only.

In that context it may be convenient to define that the term“distal end” in the appended fig ures is meant to refer to the end of the injection device securing the needle cannula and pointing towards the user during injection, whereas the term“proximal end” is meant to refer to the opposite end usually carrying the dose dial button as depicted in figure 1. Distal and proximal is meant to be along an axial orientation extending along the longitudinal axis“X” of the injection pen device as also disclosed in figure 1.

Figure 1 and figure 2 disclose the injection device prior to use. The mechanics of the injec tion device including the piston drive system is encapsulated in a housing structure 1 which proximally carries a rotatable dose setting button 2 which is rotatable by a user to thereby set the size of the dose to be injected.

The distal part of the housing is in figure 1 covered by a removable protective cap 40 which the user must remove before performing an injection. This protective cap 40 is on the outside provided with a longitudinal raised tongue 41 to enhance the grip when the user rotates the protective cap 40 as will be explained. Figure 2 disclose the injection device with the protec tive cap 40 removed.

As disclosed in figure 3, the housing structure 1 , in the present embodiment, comprises a base part 10, a cartridge holder part 20 and an initiator part 30 as also shown in WO

2019/238,806. These parts 10, 20, 30 are preferably clicked together to form one housing structure 1 but could be connected in alternative ways. The housing structure 1 is in the dis closed embodiment made from three different components 10, 20, 30 which are locked to gether to form the full housing structure 1 but the housing structure 1 could be made from any number of individual parts.

The cartridge holder part 20 is in use covered by the movable needle shield 50 as also seen in figure 2. Internally the cartridge holder part 20 secures the cartridge 5 which contains the liquid drug to be injected. The cartridge 5 is axially secured to the cartridge holder part 20 by a number of inwardly bendable arms 21 (preferably 2 arms) on the cartridge holder part 20 which grips behind the neck 6 of the cartridge 5 when the cartridge 5 is inserted into the car tridge holder part 20. Since the neck 6 has a recess between the glass body and the metal bend, the cartridge 5 is free to move this distance in the axial direction. The movable dis tance that the cartridge 5 is able to move axially relatively to the cartridge holder part 20 and thus the housing structure 1 is illustrated as the distance“A” in figure 3.

The proximal end of the cartridge 5 is internally held by a number of not shown inwardly pointing ribs provided inside the base part 10 of the housing structure 1. When the cartridge 5 is moved proximally the distance“A” as will be explained, the plunger 7 inside the cartridge 5 will be maintained in its initial position by the piston rod 3 (shown in in figure 5) such that a pressure will be build up inside the interior of the cartridge 5. Also, as the cartridge 5 is moved proximally, the proximal part of the cartridge 5 is moved into a tighter contact with the inwardly pointing ribs on the inside the base part 10. During this movement the inwardly pointing ribs will be somewhat crushed which improves the stability of the cartridge 5.

The base part 10 secures the piston rod drive system which is often referred to as the dose engine. This dose engine is preferably a torsion spring drive mechanism as described in de tails in WO 2019/002020, which is hereby incorporated by reference. In order to set the size of the dose to be injected, the user rotates the dose setting button 2 which strains a torsion spring and moves a scale drum 14 helically inside the housing structure 1. As the user ro tates the dose setting button 2, the size of the dose being set can be visually inspected in a window 11 in the base part 10 of the housing structure 1 as indicia provided on the scale drum 14 rotates by the window 11 in the housing structure 1. During injection, the torque stored in the torsion spring is released such that the torsion spring drives the piston rod 3 in the distal direction which moves the plunger 7 forward inside the cartridge 5 also in the distal direction. Simultaneously, the scale drum 14 returns to its zero position.

The cartridge 5 is typically a standard cartridge 5 made from a glass material being inert to the liquid drug and which cartridge 5 is distally sealed by a pierceable and self-sealing sep tum 8 and wherein the plunger 7 can be moved in the distal direction to build up pressure inside the interior of the cartridge 5 such that the liquid drug contained inside the interior of the cartridge 5 can be pressed out through the lumen 83 of a needle cannula 80 penetrated through the pierceable septum 8.

When assembling the housing structure 1 , the base part 10 and the initiator part 30 are clicked together. For this purpose, the initiator part 30 is on the outer surface provided with a number of protrusions 31 , 32 which engage a similar number of openings 12, 13 provided in the base part 10. The respective protrusions 31 , 32 and the respective openings 12, 13 are rotationally spaced from each other such that once clicked together, the initiator part 30 is axially and rotationally locked to the base part 10.

When the initiator part 30 is to be connected to the base part 10, the initiator part 30 is fitted over the cartridge holder part 20 which is henceforth axially sandwiched between the initiator part 30 and the base part 10. The initiator part 30 is for this purpose provided with an axial indentation 33 which engages a similar axially raised portion 22 provided on the cartridge holder part 20 such that the cartridge holder part 20 is axially and rotationally fixed between the initiator part 30 and the base part 10. The click fit between the initiator part 30 and the base part 10 thus also secures the cartridge holder part 20 such that the base part 10, the cartridge holder part 20 and the initiator part 30 cannot rotate nor move axially relatively to each other. They operate as one housing structure 1 and can easily be connected in alterna tive ways.

The initiator part 30 is provided with a helical track 45 which leads to a first sloped edge 35 and the cartridge holder 20 is in the same way provided with a second sloped edge 23.

When the housing structure 1 is assembled, the helical track 45 thus continues between the first sloped edge 35 and the second sloped edge 23.

As there are two such helical tracks 45 disclosed in this embodiment, the various elements relating to these helical tracks 45 are provided in pairs. It is thus to be understood that even if described in singularity in the present text, the various elements can be provided in plural.

As previously mentioned and disclosed, the initiator part 30 is provided with a peripheral track 34 on the outer surface for rotational guiding the protective cap 40 (See e.g. figure 2).

In that respect the protective cap 40 is on an inner surface provided with an inwardly pointing protrusion 42 which engages the peripheral track 34 through an axial opening 36 in the pe ripheral track 34. Preferably, two or more axial opening 36 are provided and the protective cap 40 disclosed in figure 5 is preferably provided with two or more protrusions 42. When two axial openings 36 and two inwardly pointing protrusions 42 are provided, the user is forced to rotate the protective cap 40 less than 180 ° and preferably around approximately 150 ° be fore the protective cap 40 can be axially removed.

The needle shield 50 is proximally provided with extensions 53 which each carry an outward ly pointing protrusion 52. In the disclosed embodiment there are two such extensions 53 and two outwardly pointing protrusions 52, however, any random number can be provided. These outwardly pointing protrusions 52 are guided in the helical tracks 45 such that the needle shield 50 moves helically along the helical track 45 when rotated. The needle shield 50 is henceforth helically movable in relation to the housing structure 1 preferably from a first position wherein the needle shield 50 is unable to translate axially to a second position wherein the needle shield 50 can be translated axially during injection.

When the outwardly pointing protrusions 52 are operating in the helical track 45, the needle shield 50 can only perform a helical movement, however, once the protrusions 53 reach the second position, the needle shield 50 is able to translate axially to thereby perform an injec tion.

The injection device is disclosed in exploded view in figure 4 and in a cross-sectional view in figure 5. The main parts of the injection device are;

The housing structure 1 which comprising a base part 10, a cartridge holder part 20 and an initiator part 30. Neither figure 4 nor figure 5 shows the base part 10, which however can be seen in figure 3.

The protective cap 40 which is removable after being rotated. In figure 5, the protec tive cap 40 is not disclosed.

The needle shield 50 which is helically movable in relation to the housing structure 1.

The cleaning assembly 60 which has a cleaning reservoir 74 containing the cleaning solvent.

The needle cannula 80 for transporting the liquid drug through a lumen 83.

The needle hub 90 which carries the needle cannula 80.

The needle shield 50 which is further disclosed in figure 6 is externally provided with one or more longitudinal tongues 51 (see e.g. figure 4) and two outwardly pointing protrusions 52 as disclosed in figure 6. The longitudinal tongues 51 can be provided in any axial position de pending on the location of the raised tongue 43 inside the protective cap 40 which it has to engage as will be explained. Peripherally the longitudinal tongues 43 can be offset any number of degrees from the raised tongues 51 in the delivery state of the injection device such that the protective cap 40 has to be rotated a certain number of degrees before engaging the raised tongues 51 on the needle shield 50.

The raised tongues 43 and the inwardly pointing protrusions 42 provided on the inner surface of the protective cap 40 are indicated by punctured lines in figure 4 as they are not viewable form the outside. However, they are viewable in the cross-sectional views of figure 7.

Distally the movable needle shield 50 carries a cleaning assembly 60 as disclosed in WO 2019/238,806. The cleaning assembly 60 (indicated by a bracket in figure 4) comprises a front element 65 which is provided with a number of outwardly pointing protrusions 66 fitting into slits 54 inside the needle shield 50 (see e.g. figure 4) which thus allows the front element 65 to be click-fitted to the movable needle shield 50 such that the front element 65 moves together with the movable shield 50 in all directions including the rotational direction. The front element 65 could alternatively be moulded as an integral part of the movable needle shield 50.

Permanently secured to the front element 65 is a chamber part 70 of which the cleaning res ervoir 74 (see e.g. figure 5) is an integral part as disclosed in WO 2019/238,806. The clean ing reservoir 74 is distally covered by a front septum 61 which is tightly connected to the chamber part 70 by a metal bend 62 as it is commonly known from any well-known septum in a cartridge.

The chamber part 70 is provided with a protrusion 72 which locks the chamber part 70 to the front element 65 to form one element. The front element 65, the chamber part 70, the front septum 61 and the metal bend 62 of the cleaning assembly 60 thus operates as one integral assembly following both axial and rotational movements of the movable needle shield 50.

The cleaning reservoir 74 is proximally sealed by a movable plunger 75 which is able to move in the proximal direction as the cleaning reservoir 74 is being filled with liquid drug from the cartridge 5. The movable plunger 75 is in the disclosed embodiment formed as a soft rubber part 76 which is glued or clicked onto a more solid part 77 or alternatively formed in a two-component (2K) moulding. In either case the movable plunger 75 (bracket in figure 4) comprises the soft distal plunger 76 and the more rigid proximal part 77. In a preferred embodiment, the cleaning solvent inside the cleaning reservoir 74 is identical to the liquid drug contained in the cartridge 5. The preservative of the liquid drug thus oper ates as the active cleaning agent for cleaning the distal tip 81 of the needle cannula 80 be tween injections. It is henceforth a prerequisite that the liquid drug contains a preservative which is well known as many liquid insulin and GLP-1 formulations contain meta-cresol and/or phenol in order to prevent growth of bacteria in the liquid drug.

The chamber part 70 is further provided with knobs 73 which abut against the distal end of the needle hub 90 such that whenever the chamber part 70 moves helically together with the needle shield 50 this helical movement is transferred to an axial movement of the needle hub 90 as it is explained in WO 2019/238,806.

In order for the needle hub 90 to move purely axially it is guided axially by straight rails 24 provided distally on the cartridge holder part 20. These rails 24 extend parallel to the longitu dinal axis X of the injection device. Henceforth, the needle hub 90 is forced to move tele scopically along the longitudinal axis X at all times.

The needle cannula 80 which is mounted in the needle hub 90 is distally provided with a sharp tip 81 for penetrating through the skin of user and a proximal end 82 which is inserted into the cartridge 5. The liquid drug flows through the hollow lumen 83 and the needle cannu la 80 is preferably glued to the needle hub 90, but could be secured in alternative ways.

In order to initiate the injection device, the user thus has to rotate and remove the protective cap 40. This is done by rotating the inwardly pointing protrusions 42 in the peripheral track 34 on the initiator part 40 until the inwardly pointing protrusions 42 are able to slip away through the axial openings 36.

The thereby mandatory rotation of the protective cap 40 is transferred to a rotation of the needle shield 50 by the interface between the raised tongue 43 inside the protective cap 40 and the longitudinal tongues 51 provided on the needle shield 50. However, in one example, the longitudinal tongue 51 and the raised tongues 43 are peripherally offset approximately 60 ° such that the protective cap 40 must be rotated approximately 150 ° in order to rotate the needle shield 90 °. When the needle shield 50 is rotated it moves helically as the outwardly pointing protrusions 52 on the needle shield 50 are engaged in the helical track 45 in the initiator part 30.

The cleaning assembly 60 which follows the helical movement of the needle shield 50 is on the outside provided with knobs 73 which engage the distal end of the needle hub 90. Con sequently, when the needle shield 50 and the cleaning assembly 60 are rotated and moves helically, the needle hub 90 is forced to follow the cleaning assembly 60 in its axial move ment as the needle hub 90 is guided translationally in the tracks 24 distally on the cartridge holder part 20. This is indicated by the arrow“73” in figure 10.

The cartridge 5 and the needle hub 90 are separated by a transfer element 100 which trans fers the axial movement of the needle hub 90 onto the cartridge 5 as will hereafter be ex plained.

In WO 2019/238,806, the transfer element or back-needle plug is numbered with reference number“85” in the figures and is exposed to a purely linear movement when the needle hub (numbered“90”) is moved axially in the proximal direction. The transfer element 100 dis closed in the embodiment of the present patent application differs from the back needle plug of WO 2019/238,806, due to the rotation performed by the transfer element 100 when the needle hub 90 is translated in the proximal direction as will be explained.

The transfer element 100 is disclosed in further details in figure 8A-D and comprises a radial plate-like structure 101 from which an axial cup-like structure 102 is moulded perpendicular to the plate-like structure 101. Further, a pair of triangular wings 103 points in the distal direc tion in the assembled pen device as disclosed in figure 4. The cup-like structure 102 is hol low and houses a soft septum 104 in which the proximal part 82 of the needle cannula 80 is parked when the pen device is in its out-of-pack state (state 1). The soft septum 104 is also seen in figure 5.

On the periphery of the plate-like structure 101 a number of outwardly pointing protrusions 105 are provided. In the disclosed embodiment two such outwardly pointing protrusions 105 are provided. The cup-like structure 102 of the transfer element 100 is further provided with a number, preferably two, of outwardly pointing knobs 106 for generating a movement of the transfer element 100 relatively to the housing structure 1 as will hereafter be explained.

Figure 9 A-C discloses various views of the needle hub 90. As best seen in figure 9B, the needle hub 90 is provided with an open track 91 for guiding the transfer element 100. For this purpose, the outwardly pointing protrusion 105 of the transfer element 100 engages this open track 91 as it is disclosed in figure 11 and 12. Further, the open track 91 , of which a pair is provided in the preferred embodiment, is provided with an angled locking arm 92. These angled locking arms 92 are angled inwardly towards the centre line X of the housing structure 1 as best seen in figure 9A. Proximally, the needle hub 90 is provided with a num ber of proximally extending guiding arms 93A, 93B. In the preferred embodiment there are provided two pairs of theses arms 93A, 93B such that a total of four arms 93 are provided. At the position B-B in figure 9B, a radial bottom 94 is provided which carries the needle cannula 80. The radial bottom 94 is further provided with a pair of openings 95 as disclosed in figure 9C which discloses a view along the line B-B in figure 9B.

In figure 10, the needle hub 90 of figure 9A-C is disclosed in a perspective view together with the transfer element 100 and the cartridge holder part 20.

As mentioned before, the cartridge holder part 20 is a part of the housing structure 1 and does not move axially nor rotationally. A pair of flexible arms 21 secures the cartridge 5 such that the cartridge 5 is allowed to move the distance“A” in the axial direction as indicated in figure 3. When the cartridge 5 is inserted into the cartridge holder part 20 from the proximal end of the cartridge holder part 20, the metal bend securing the septum 8 is forced past the flexible arms 21 which thus grips into the free space between the metal bend and the neck part of the glass container of the cartridge 5. This engagement secures the cartridge 5 to the cartridge holder part 20 and allows the cartridge 5 to be moved slightly in the axial direction.

The cup-like structure 102 of the transfer element 100 engages the cartridge holder part 20 and is guided rotationally to the cartridge holder part 20 as will be explained. To move the transfer element 100, the cup-like structure 102 is on the outer surface provided with a num ber of outwardly pointing knobs 106 which engages a sloped inner surface 25 provided on the inner distal surface of the cartridge holder part 20 as best seen in figure 10. The needle hub 90 is guided purely axially relatively to the cartridge holder part 20 as the guiding arms 93A, 93B slides along axial guiding rails 24 provided distally on the cartridge holder part 20. The engagement between the arms 93A, 93B and the axial rails 24 on the needle holder part 20 thus prevents the needle hub 90 from rotating relatively to the housing structure 1 during its axial translation.

The transfer element 100 is located inside the needle hub 90 as it can be seen in figure 5. The needle hub 90 is thus provided with a number, preferably two, inwardly pointing arms 96 which prevents the transfer element 100 from escaping from the needle hub 90 in the proxi mal direction.

It is thus a prerequisite that the needle hub 90 translates purely axially when the injection de vice is being initiated i.e. when the cleaning reservoir 74 is being filled with preservative con taining liquid drug from the cartridge 5. This axial movement of the needle hub 90 is trans ferred to a rotation of the transfer element 100 due to the sloped surface 97 on the needle hub 90 engaging the outwardly pointing protrusions 105 and the triangular wings 103 engag ing the openings 95 as will be explained. For this purpose, each of the triangular wings 105 are provided with a sloped guiding surface 107. However, any kind of guiding mechanism which transfers a straight axial movement of the needle hub 90 to a rotation of the transfer element 100 could be provided and the following is only one preferred example of such mechanism. In the disclosed embodiment the transformation of the purely axial translation of the needle hub 90 into a rotation of the transfer element 100 is divided into two consecutive rotational movements, however the number of rotational movements is not decisive for the claimed invention.

The straight axial movement of the needle hub 90 arises from the helical movement of the cleaning assembly 60 attached to the needle shield 50 which causes the knobs 73 to move helically in the proximal direction and to bring the needle hub 90 along in the axial movement thus moving the needle hub 90 along the rails 24. This straight axial translation introduced by the knobs 73 riding on the distal surface of the needle hub 90 is indicated by the arrow marked“73” in figure 10.

It can further be seen from figure 10 that the helical flange 23 of the helical track 45 termi nates into a peripheral radial extension track 26 which leads the outwardly pointing protru sions 52 on the needle shield 50 under the axially raised portion 22 and into an axial pas- sage 27 (second position) allowing the protrusion 52 and thus the needle shield 50 to move straight in the proximal direction during injection. However, as long as the outwardly pointing protrusion 52 is in the helical track 45 or its peripheral radial extension track 26 (first position) it is not possible to move the needle shield 50 in the straight axial direction thus it is only possible to perform an injection when the needle shield 50 has been rotated to a position wherein the outwardly pointing protrusions 53 are positioned in the open axial passage 27 below the axially raised portion 22. The needle shield 50 henceforth needs to be rotated from the first position to the second position before an injection can be performed.

The figure 11 A-G and 12A-G illustrates the various states of the initiation procedure i.e. the procedure in which a predetermined volume of the preservative containing liquid drug is transferred from the interior of the cartridge 5 and into the cleaning reservoir 74 through the lumen 83 of the needle cannula 80.

Figure 11A-G discloses the interface between the transfer element 100 and the cartridge holder part 20 during axial movement of the needle hub 90. However, in the figures 11A-G, the needle hub 90 has been visually removed to better visualize the interface.

Figure 12A-G disclose the same states as figure 11A-G, however in these figures the needle hub 90 is partly disclosed such that the engagement between the open track 91 in the needle hub 90 and the outwardly pointing protrusion 105 on the transfer element 100 can be seen. However, the most distal part of the needle hub 90 has been visually cut away along the line B-B of figure 9B. In figure 12A the line C-C follows the line B-B of figure 9B.

The various states 1 to 7 are defined as;

State 1 : Out-of-pack. The state of the injection device when the injection device is delivered to the end-user and before the initiation process has been initiated by the user.

States 2: Ready to be filled. In this state the cleaning reservoir is ready to be filled.

State 3, 4 and 5: Filling. In these states the cartridge 5 is being moved axially to build up a pressure inside the cartridge 5 which forces a volume of the preservative containing liquid drug from the cartridge 5, through the lumen 83 of the needle cannula 80 and into the clean ing reservoir 74. State 6: Over-travel. The final step of filling the predetermined volume of preservative con taining liquid drug into the cleaning reservoir.

State 7: Locked. In this state the initiation of the injection device is completed, and the injec tion device is ready to perform an injection.

State 1 - Figure 1 1A + 12A:

In this first state wherein, the injection device is delivered to the end-user, the user starts to initiate the injection device by rotating the protective cap 40 to remove it which generates a rotation of the needle shield 50. Due to engagement of the outwardly pointing protrusion 52 on the needle shield 50 with the helical track 45 on the initiator part 30, the needle shield 50 starts to move helically in the proximal direction. As previously explained, the cleaning unit 60 follows the helical movement and the knobs 73 pushes the needle hub 90 in the proximal direction (as indicated by the arrow“73” in figure 10) and since the needle hub 90 is guided axially by the longitudinal rails 24 distally on the cartridge holder part 20, the needle hub 90 performs a purely axial translation in the proximal direction.

The transfer element 100 as seen in figure 8A-D carries centrally the septum 104 which is secured to the transfer element 100 e.g. by a 2K moulding, by gluing, by snap or by other means. In the first state, the proximal end 82 of the needle cannula 80 is parked in this sep tum 104 which maintains the proximal part 82 of the needle cannula 80 sterile.

State 2 - Figure 1 1 B + 12B:

Due to the friction between the septum 104 secured to the transfer element 100 and the needle cannula 80 secured to the needle hub 90, the transfer element 100 follows the axial movement of the needle hub 90 and the needle cannula 80 as it travels in the proximal direc tion which brings the outwardly pointing knobs 106 on the transfer element 100 to a position wherein the outwardly pointing knobs 106 are aligned with the sloped inner surface 25 pro vided on the inner distal surface of the cartridge holder part 20.

As in all states, the needle hub 90 with the needle cannula 80 travels purely axially as the needle hub 90 is guided by the linear rails 24 provided on the cartridge holder part 20. State 3 - Figure 11C + 12C:

As the needle hub 90 is being moved further in the proximal direction as disclosed in figure 12C, the sloped surface 97 of the inner track 91 engages the outwardly pointing protrusion 105 and forces the transfer element 100 carrying the outwardly pointing protrusion 105 to rotate as illustrated in figure 11C.

The sloped inner surface 25 inside the cartridge holder part 20 forces the outwardly pointing knobs 106 and thus the transfer element 100 to move in the proximal direction as the transfer element 100 is rotated.

Thus, the engagement between the sloped surface 97 on the needle hub 90 and the out wardly pointing protrusion105 on the transfer element 100 makes the transfer element 100 rotate and the engagement between the sloped inner surface 25 on the cartridge holder part 20 and the outwardly pointing knob106 on the transfer element 100 makes the transfer ele ment 100 move in the proximal direction.

The transfer element 100 henceforth performs a helical movement as the needle hub 90 is being translated linearly.

State 4 - Figure 11 D + 12D (and figure 13):

Once the outwardly pointing protrusion 105 has been rotated down the sloped surface 97 as disclosed in figure 12D and is delivered to the axial part of the open track 91 , the triangular wings 103 have been rotated into alignment with the opening 95A-B in the radial bottom 94 of the needle hub 90.

This is also illustrated in figure 13 wherein a further part of the needle hub 90 has been cut open to illustrate the engagement between the sloped guiding surface 107 on the triangular wing 103 and the side surfaces 99 of the openings 95 (A, B). The side surfaces 99 are also identified in figure 10.

State 5 - Figure 11 E + 12E: Further axial movement of the needle hub 90 as illustrated in figure 12E makes the sloped guiding surface 107 on the triangular wing 103 engages the side surfaces 99 of the openings 95A-95B which forces the transfer element 100 to continue its rotation.

This further rotation of the transfer element 100 brings the outwardly pointing knobs 106 on the transfer element 100 further along the sloped inner surface 25 such that the transfer ele ment 100 is moved further in the proximal direction.

The helical movement of the transfer element 100 in the proximal direction is directly con veyed to the cartridge 5 as the cup-like structure 102 of the transfer element 100 directly abuts the cartridge 5 as disclosed in figure 5. For this purpose the transfer element 100 has a proximal rim 108 as disclosed in figure 8C which abut directly on the metal bend securing the distal septum 8 on the cartridge 5.

However, the transfer element 100 does not explicitly need to abut the cartridge 5. In one example another mechanical structure can be provided between the transfer element 100 and the cartridge 5 as long as the movement of the transfer element 100 is transformed to a movement of the cartridge 5.

During the states 3, 4 and 5, the cartridge 5 is moved the distance“A” (figure 3) in the proxi mal direction. As seen in figure 5, the plunger 7 inside the cartridge 5 is prevented from mov ing in the proximal direction due the engagement with the piston rod 3 and possible also a piston rod foot 4 which can be provided between the piston rod 3 and the plunger 7. Conse quently, a pressure is build up inside the cartridge 5. This pressure forces a volume of the liquid drug contained inside the cartridge 5 through the lumen 83 of the needle cannula 80 and into the cleaning reservoir 74 where this volume will operate as a cleaning agent due to its content of preservatives and thus keep the distal tip 81 of the needle cannula 80 clean between consecutive and multiple injections.

The size of the transferred volume is a multiple of the inner cross-sectional area of the car tridge 5 (which is the same as the surface area of the plunger 7) and the distance“A” which the cartridge 5 is moved proximally.

State 6 - Figure 11 F + 12F: The next and final step of the initiation is to physically lock the needle hub 90 to the cartridge holder part 20 and thus to the housing structure 1.

This is done by securing the inwardly angled locking arm 92 on the needle hub 90 axially be hind the locking flange 28 provided on the cartridge holder part 20.

As seen in figure 10 there are two such locking flanges 28A-28B to accommodate the two angled locking arms 92.

However, due to various tolerances on the moulded polymer parts making up the injection device, the needle hub 90 and the angled locking arm 92 needs to be moved a short dis tance further in the proximal direction than just to the exact position of the locking flange 28 which can be seen in figure 12F. When performing this over-travel, i.e. move the needle hub 90 slightly further in the proximal direction, the arm 93B will engage the sloped surface 29 on the cartridge holder part 20 which will thus slightly bend the proximal end of the arm 93B ra dially in a peripheral direction and thus apply a torque on the needle hub 90 .

State 7 - Fiqure 11 G + 12G (and fiqure 5):

Once the injection device has been initiated and the predetermined volume of preservative containing liquid drug has been transferred to the cleaning reservoir 74, the knobs 73 has been rotated to a position wherein the knobs 73 are positioned in the undercut portion 98 of the needle hub 90 as e.g. seen in figure 10.

When the knobs 73 do not push against the end surface of the needle hub 90, the arm 93B which is pressed against the sloped surface 29 forces the needle hub 90 a short distance in the distal direction whereby the arm 92 abut against the flange 28 such that the needle hub 90 is locked to the cartridge holder part 20.

In state 7 the initiation is finished and the needle hub 90 is irreversible locked to the housing structure 1 as will be explained. The following has thus happened during the states 1 to 7:

The needle hub 90 has been translated purely axially a distance in the proximal direc tion. The proximal part of the needle cannula 80 has pierced through the septum 8 of the cartridge 5.

The transfer element 100 has been rotated helically into the cartridge holder part 20. The cartridge 5 has been pushed a short distance in the proximal direction.

- A predetermined volume of liquid drug has been pressed out from the cartridge 5 and into the cleaning reservoir 74.

The needle hub 90 has been irreversible secured to the housing structure 1.

When the predetermined volume of liquid drug has been transferred into the cleaning reser voir 74 the injection device is ready for use. The ready to inject state of the injection device is also depicted in figure 5.

Further, as best seen in figure 11G the non-sloped radial surfaces on the engagement be tween the outwardly pointing knob 106 on the transfer element 100 and the cartridge holder part 20 abut against each other which prevents the transfer element 100 from movement in the distal direction.

Also, in this position the metal bend on the cartridge 5 is pressed against the flexible arm 21 on the cartridge holder part 20 while the proximal end of the cartridge 5 rest against the in wardly pointing ribs in the base part of the housing structure 1.

Simultaneously an axial part 109 on each wing 103 identified e.g. in figure 8D has entered into the opening 95A, 95B which prevents the transfer element 100 from rotation relatively to the needle hub 90 as it is rotationally prevented by the side surfaces 99 of the openings 95A, 95B engaging the axial parts 109 of the wings 103.

Consequently, the transfer element 100 is prevented from rotation by the needle hub 90 and the needle hub 90 is both rotational and axially locked to the cartridge holder part 20. Thus both the transfer element 100 and the cartridge holder 90 are secured to the housing struc ture 1 both rotationally and axially.

In the disclosed embodiment, the filling of the cleaning reservoir 74 requires approximately a 90 ° rotation of the needle shield 50 such that the outwardly pointing protrusion 52 is moved through the helical track 45 of the initiator part 30 and into the continued helical track 45 de fined by the first sloped edge 35 on the initiator part 30 and the second sloped edge 23 on the cartridge holder part 20. Since the raised tongues 43 and the longitudinal tongue 51 in one example are offset by approximately 60 ° this requires the protective cap 40 to be rotat ed approximately 150 °.

Once the needle shield 50 has been rotated 90 °, the protective cap 40 has, in the above ex ample, been rotated approximately 150 ° and the inwardly pointing protrusion 42 inside the protective cap 40 has been rotated to alignment with the axial opening 36 where after the protective cap 40 can be axially removed.

The inwardly pointing protrusion 52 on the needle shield 50 is now positioned at the start of the continued track 45 defined by first sloped edge 35 on the initiator part 30 and the second sloped edge 23 on the cartridge holder part 20.

Before an injection can be performed, the user must manually rotate the needle shield 50 further such that the inwardly pointing protrusion 52 slides along the sloped edge 23 and on to the radial extension track 26 as disclosed in figure 10. During this rotation the needle shield 50 moves helically in the proximal direction such that the distal tip 81 of the needle cannula 80 appears outside and distal to the needle shield 50. Any overpressure present in the liquid system is thus equalized with the atmospheric pressure of the surroundings in what is referred to NPR (Needle Pressure Release).

When the outwardly pointing protrusion 52 is positioned in the radial extension track 26 a fur ther rotation of the needle shield 50 moves the outwardly pointing protrusion 52 into the axial passage 27 in which (second) position it is possible to translate the needle shield 50 tele scopically in the straight axial direction and thus to perform an injection.

The injection is performed by pushing the distal surface of the needle shield 50 against the skin of the user whereby the needle shield 50 is translated in the proximal direction in a pure ly axial movement. This movement is henceforth transferred to the spring engine such that the torque stored in the torsion spring is, at least partly, released to drive the piston rod 3 in the distal direction to thereby inject the set dose. Following the injection, the user removes the needle shield 50 from the skin whereby a not shown resilient element urges the needle shield 50 back into the previous position.

In this previous position occurring after the injection and following removal of the needle shield 50 from the skin, the user can rotate the needle shield 50 back into the first position in which the outwardly pointing protrusion 52 is first guided in the radial extension track 26 and thereafter along the sloped edge 23 until the distal tip 81 of the needle cannula 80 is back inside the cleaning reservoir 74. Some preferred embodiments have been shown in the foregoing, but it should be stressed that the invention is not limited to these but may be embodied in other ways within the sub ject matter defined in the following claims.

Claims

CLAIMS:

1. A pre-filled injection device with a piston rod drive system for delivering doses of a pre servative containing pharmaceutical liquid drug, comprising:

A housing structure (1) supporting a non-replaceable cartridge (5) which is axially movable a distance (A) in relation to the housing structure (1) and the piston rod drive system, wherein; the cartridge (5) distally comprises a pierceable septum (8) and proximally compris es a movable plunger (7) defining an interior containing a preservative containing pharmaceutical liquid drug and wherein the movable plunger (7) has a proximal sur face abutting the piston rod drive system, and which piston rod drive system for moving the movable plunger (7) in the distal direc tion inside the cartridge (5) and which plunger (7) is prevented from movement in the proximal direction (e.g. by a one-way ratchet),

A needle hub (90) securing a needle cannula (80), wherein; the needle cannula (80) has a distal part with a distal tip (81) and an opposite prox imal part (82) and a lumen (83) there between, and which needle hub (90) is movable in a proximal direction to insert the proximal part (82) of the needle cannula (80) through the pierceable septum (8) and into the inte rior of the cartridge (5),

A needle shield (50) which is rotatable from a first positon to a second position, wherein; the needle shield (50) distally carries a cleaning reservoir (74) containing a volume of the preservative containing pharmaceutical liquid drug when filled, for cleaning at least the distal tip (81) of the needle cannula (80) between subsequent injections, and rotation of the needle shield (50) from the first positon to the second position is transformed to a movement of the needle hub (90) in the proximal direction, A transfer arrangement for transferring movement of the needle hub (90) in the proximal di rection to a movement of the cartridge (5) in the proximal direction,

Characterized in that, the needle hub (90) is guided translationally in relation to the housing structure (1) when moved proximally, and the transfer arrangement comprises a transfer element (100) for op erating the cartridge (5), wherein; the transfer element (100) engages the needle hub (90) such that the axially guided movement of the needle hub (90) in the proximal direction is transferred to a helical movement of the transfer element (100) in the proximal direction whereby the trans fer element (100) abuts and moves the cartridge (5) proximally relatively to the housing structure (1) to thereby force liquid preservative containing drug from the in terior of the cartridge (5) through the lumen (83) of the needle cannula (80) and into the cleaning reservoir (74).

2. A pre-filled injection device according to claim 1 wherein the needle hub (90) is guided ax ially in relation to the housing structure (1) in an axial guiding structure (24).

3. A pre-filled injection device according to claim 2, wherein the housing structure (1) com prises a cartridge holder part (20) comprising the axial guiding means (24) for guiding the needle hub (90) axially.

4. A pre-filled injection device according to claim 2 or 3, wherein the needle hub (90) and the transfer element (100) are provided with engaging means for transferring the guided transla tional movement of the needle hub (90) to a rotation of the transfer element (100).

5. A pre-filled injection device according to claim 4, wherein the engaging means comprises a protrusion (105) engaging a track (91).

6. A pre-filled injection device according to claim 5, wherein the transfer element (100) car ries the protrusion (105) and the needle hub (90) carries the track (91).

7. A pre-filled injection device according to claim 5 or 6, wherein the track (91) has a sloped configuration (97).

8. A pre-filled injection device according to claim 4, wherein the engaging means comprises an axial wing (103) and an opening (95).

9. A pre-filled injection device according to claim 8, wherein the transfer element (100) car ries the axial wing (103) and the needle hub (90) carries the opening (95).

10. A pre-filled injection device according to claim 9, wherein the axial wing has a sloped sur face (107).

11. A pre-filled injection device according to any of the previous claims, wherein the housing structure (1) and the transfer element (100) comprises abutment means for moving the trans fer element (100) axially when the housing structure (1) and the transfer element (100) are rotated relatively to each other.

12. A pre-filled injection device according to claim 1 1 , wherein the abutment means compris es a knob (106) and a sloped surface (25).

13. A pre-filled injection device according to claim 12, wherein the transfer element (100) car ries the knob (106) and the housing structure (1) carries the sloped surface (25).

14. A pre-filled injection device according to any of the previous claims, wherein the needle shield (50) in the first position is prevented from translating axially and in the second position is allowed to translate axially in relation to the housing structure (1).

15. A pre-filled injection device according to claim 14, wherein the needle shield (50) in the first position is helically movable in relation to the housing structure (1).