WO2022063762A1

WO2022063762A1 - An injection needle unit having a solid cleaning plug

Info

Publication number: WO2022063762A1
Application number: PCT/EP2021/075914
Authority: WO
Inventors: Henrik Bengtsson; Jesper Peter Windum; Rasmine SABRA; Vera Pinto GLENTING
Original assignee: Novo Nordisk A/S
Priority date: 2020-09-23
Filing date: 2021-09-21
Publication date: 2022-03-31

Abstract

The invention relates to an injection needle unit having a needle cannula to be used for multiple injections and a needle shield carrying a solid polymer cleaning plug for cleaning the distal part of a needle cannula between injections. The needle shield and a needle cannula are rotated relatively to each between each injection such that the needle cannula passes through the solid polymer cleaning plug in a new angular position at each new injection.

Description

An Injection Needle Unit Having a Solid Cleaning Plug.

THE TECHNICAL FIELD OF THE INVENTION:

The invention relates to an injection needle unit and especially such injection needle unit having facilities for cleaning the needle cannula between injections.

DESCRIPTION OF RELATED ART:

WO 2014/064100 discloses a pre-filled injection device wherein the distal tip of the needle cannula is cleaned between subsequent injections. In one embodiment the cleaning arrangement comprises a solid plug which in one example is made from a suitable polymer containing an anti-bacterial material.

However, when using a solid plug as disclosed in figure 11 to 13 in WO 2014/064100 the distal tip of the needle cannula penetrates the solid plug in the same position at each injection.

DESCRIPTION OF THE INVENTION:

It is an object of the present invention to provide an injection needle unit wherein the distal tip of the needle cannula is cleaned in a solid plug between subsequent injections but wherein the distal tip of the needle cannula is only exposed to the same part of the solid plug once.

Accordingly, in one aspect of the present invention an injection needle assembly is provided which comprises:

A base part such as a housing or the like being temporally or permanently connectable to an injection device and having a centre axis.

A needle shield axially movable along the centre axis from a first position to a second position. The first position preferably being one wherein the distal tip of the needle cannula is concealed and the second position being one wherein the distal tip of the needle cannula is exposed. A resilient means disposed between the base part and the needle shield for urging the needle shield distally into the first position. The resilient element is preferably a compression spring but can be any kind of resilient element capable of forcing the base part and the needle shield apart.

A needle cannula extending along the centre axis and having a distal part with a grinded distal tip for penetrating the skin of a user.

A solid pierceable cleaning plug for cleaning at least the distal tip of the needle cannula between injections and wherein the solid pierceable cleaning plug is carried by the needle shield.

In order to secure that the needle cannula do not pass through the solid plug following the same path, the needle cannula and the solid pierceable cleaning plug are arranged to be rotatable in relation to each other between injections.

It has been observed that a needle cannula when passing through a solid plug e.g. along a centre line will during its passage divert from the centre line in the direction of the grind at the tip of the needle cannula and hence follow a sloped path through the solid plug. This principle is illustrated in figure 1. Based on this observation it is realized that if the needle cannula and the solid plug are rotated relatively to each and around the centre line between each injection, the needle cannula will pass through the solid plug following a new path next time an injection is being performed.

Henceforth, should the needle cannula and the solid plug be rotated in relation to each other at any time either during injection or when moving back through the solid plug after injection, the needle cannula will follow a new path through the solid plug at the next injection.

The solid pierceable cleaning plug is preferably made from, or comprises, a polymer containing an antibacterial additive. In a preferred example the polymeric material is a Thermo Plastic Elastomer (TPE) containing an antibacterial additive which in one example could be immobilised Zinc (Zi++) or immobilised Silver (Ag+). These ions are known to inhibit micro- bacterial growth. In a further example, the solid pierceable cleaning plug is firmly secured to the needle shield to follow all movement of the needle shield. This includes both translational and rotational movements and any combination thereof. The solid cleaning plug is preferably press-fitted into a compartment inside the needle shield but could alternatively be glued or welded to the needle shield. A 2K moulding process could also be used.

The needle shield is rotatable in relation to the base part or alternatively, the base part is rotatable in relation to the needle shield. The key is that the needle shield and the base part are rotatable in relation to each other and that this rotation is transferred to a relative rotation between the solid cleaning plug and the needle cannula such that the needle cannula and the solid plug can be shifted to a new relative angular position between each passage through the solid cleaning plug.

In order to guide the relative rotation between the needle shield and the base part, a track and protrusion interface are provided between the base part and the needle shield.

In a preferred example, the protrusions in the interface are provided on the needle shield and the track is provided in the base part, hence every time the needle shield is rotated in relation to the base part, the track and protrusions interface is able to move the needle shield including the solid polymer plug to a new position relatively to the needle cannula.

The needle cannula is preferably permanently secured in a needle hub such that the needle cannula follows all movements of the hub i.e. both translational and rotational movements. The needle cannula is preferably secured to the needle hub by gluing or welding or in any suitable manner.

In a very simple form, the needle cannula and the hub can be secured to, or be an integral part of, the base part such that a relative rotation between the needle cannula and the needle shield including the plug occurs when the needle shield is rotated in the track and protrusion interface.

As an alternative to the needle hub being secured to the base part, the needle hub can in one example be rotatably in relation to the base part. Further, as the needle cannula is secured to the needle hub to follow all movements, the relative rotation occurs between the needle hub and the needle shield carrying the solid polymer plug. The needle hub is urged against the base part by the resilient means and the needle hub abuts the base part through a number of sloped flanges. These sloped flanges introduce an axial movement to the needle hub when rotated. In a preferred example, both the base part and the needle hub are provided with sloped flanges abutting each other in pairs such that when the needle hub is rotated relatively to the base part the sloped flanges delivers an axial movement to the needle hub. The physical distance of the axial movement is determined by the angle on the sloped flanges.

In one specific example, the needle shield is provided with a number of protrusions on an inner surface. These protrusions engage protrusions provided on the needle hub such that the needle hub can be rotated by the needle shield. A rotation is in this way transferred to a similar rotation of the needle hub and thus the needle cannula. The shift in angular position of the needle cannula can thus be provided by rotation of the needle shield.

In a further aspect, the present invention refers to a prefilled injection device carrying a needle unit as herein described and claimed.

In one example of such prefilled injection device, the needle unit is releasably connected to the injection device. The needle unit can be attached to the injection device by any kind of known coupling means. Today bayonet couplings, thread connections or luer couplings are the most used for injection devices, however this does not exclude other types of releasable couplings.

In a different example the needle unit is permanently connected to the injection device. This is preferably done by irreversible connecting the base part of the needle unit to the injection device. In one example, the base part can be moulded as an integral part of the housing of the injection device. In a different example the base part of the needle unit is glued or welded to the injection device. When the needle unit is irreversible connected to the injection device, the needle cannula follows the lifetime of the prefilled injection and the needle cannula and the injection device are discarded of together.

DEFINITIONS:

An “injection pen” or “pen for injection” is typically an injection apparatus having an oblong or elongated shape somewhat like a 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 penetration 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 flowable 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. Representative drugs include pharmaceuticals such as peptides, proteins (e.g. insulin, insulin analogues 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.

“Cartridge” is the term used to describe the container actually containing the drug. Cartridges are usually made from glass but could also be moulded from any suitable polymer. A cartridge 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 septum. 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 cartridge. 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.

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 liquid 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 usually 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 durable injection devices one single injection device could last for several years, however, the average user would require 50 to 100 new cartridges per year.

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 surface 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 description 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. All references, including publications, patent applications, and patents, cited herein are incorporated 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 constructed 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 construed 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 the needle cannula passing through the solid plug.

Figure 2 show a cross-sectional view of the needle unit and part of the injection device.

Figure 3 show a perspective view of the injection device with the needle unit attached.

Figure 4 show an exploded view of the needle unit.

Figure 5 show a cross-sectional view of the needle unit.

Figure 6 show a perspective view of the needle unit with the outer layer of the housing shown with dotted lines. Figure 7A-B-C show different views of the housing.

Figure 8A-B-C show different views of the needle shield.

Figure 9A-B-C show different views of the needle hub.

Figure 10A-B show the interface between the needle hub and the housing.

Figure 11A-B-C show the needle unit in the locked position.

Figure 12A-B show the needle unit being unlocked.

Figure 13A-B show the needle unit in the unlocked position.

Figure 14A-B show the needle unit during injection.

Figure 15A-B show the needle unit with the needle shield in the fully compressed injec- tion position.

Figure 16A-B show the needle unit after injection.

Figure 17A-B show the needle unit being locked.

Figure 18A-B show the needle unit being locked.

Figure 19A-B show the needle unit in the locked position.

The figures are schematic and simplified for clarity, and they just show details, which are essential 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 “vertical”, “clockwise” and “counter-clockwise” or similar relative expressions are used, these only refer to the appended figures and not necessarily to an actual situation of use. The shown figures are schematic 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 figures 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 3. Distal and proximal is further indicated in relation to the needle unit on figure 4. Distal and proximal is meant to be along an axial orientation extending along the longitudinal axis (X) of the injection device and/or needle unit as e.g. disclosed in figure 3 and figure 4.

When referring to the rotational directions; clockwise and counter clockwise, in the following example it is to be understood that the needle unit is viewed from the distal face i.e. from a position distal to the needle unit. Clockwise is thus rotation following the arms of an ordinary clock and counter clockwise is rotation in the opposite direction.

To explain the various movements taken place in the needle unit described, the following terminology are used throughout the following example.

“Translational movement” is meant to be a strictly linear movement in the axial direction without any rotation.

“Rotational movement” is any movement of rotation around a centre which centre can be either a centre point or a centre axis i.e. having a longitudinal extension.

“Axial movement” means any movement in an axial direction e.g. along the centre axis. Such movement can be either a translational movement or include a rotational movement which thus makes it a “helical movement” as this is meant to be the combination of a translational movement and a rotational movement. “Telescopic movement” is meant to cover the situation in which a movable element moves out from, or into a base element. The movement can be translational i.e. without rotation, or the movement can include a rotation thus making the telescopic movement helical.

Figure 1 discloses the principle which the present invention is based upon. The needle cannula 10 is grinded 11 at the distal tip 12 in an angle “y” to accommodate penetration of the skin during injection. This grind 11 usually slopes towards the distal tip 12 of the needle cannula 10 and further has the effect that when the needle cannula 10 is moved translationally through a solid polymer plug 20, the needle cannula 10 automatically diverts a small angle away from the centre axis “X” in the same direction as the grind 11 slopes toward as indicated by the arrow “Z”.

The needle unit 1 is in figure 2 disclosed as a separate unit which can be attached to an injection device 5 via a bayonet coupling or a thread or any other suitable means. However, in an alternative example, the needle unit 1 can be permanently connected to the injection device 5. Figure 3 discloses the needle unit 1 attached either separable or permanently to an injection device 5. The disclosed injection device is the well-known FlexTouch® manufactured by Novo Nordisk A/S.

As disclosed in figure 4 and figure 5, the needle unit 1 comprises: o A needle hub 30 to which the needle cannula 10 is permanently attached. This attachment is such that the needle hub 30 and the needle cannula 10 move together in all directions, including the rotational direction. Examples of such attachments are gluing or welding. o A solid plug 20 made from a suitable polymer material e.g. a Thermo Plastic Elastomer (TPE) containing an antibacterial additive which in one example could be immobilised Zinc (Zi++) or immobilised Silver (Ag+). These ions are known to inhibit micro-bacterial growth and by using such elastic polymer material as a seal around the distal tip of the needle cannula micro bacterial contaminants on the surface of the needle cannula can be neutralized. Other different materials inhibiting micro bacterial growth are commercially available, e.g. from Clarion and Parx Plastic. o A needle shield 40 which can move both axially and rotationally as will be explained. o A housing (or base part) 50 which is attachable to the injection device 5 e.g. by a bayonet coupling, or alternatively permanently connected to the injection device. o A compression spring 80 encompassed between the housing 50 and the needle shield 40 and urging the needle shield 40 in the distal direction. As seen in figure 5, the compression spring 80 also presses the needle hub 30 against the housing 50. o A spring base 70 supporting the proximal end of the compression spring 80.

As best seen in figure 5, the spring base 70 is encompassed between the compression spring 80 and the needle hub 30. Since the needle hub 30, as will be explained later, is able to rotate this rotation can happen without the compression spring 80 directly abutting the needle hub 30. This allows for a smoother rotation as the proximal end of the compression spring 80 do not directly abut against the needle hub 30.

Figure 4 and figure 5 further discloses that the needle shield 40 on an outer surface is provided with a number of radial protrusions 41 which engages an inner track 51 provided in the housing 50. Any suitable number of protrusions 41 can be provided.

The inner track 51 preferably runs through on the entire periphery as an end-less track all though the inner track 51 could be provided with an end stop as will be explained. As the radial protrusions 41 follows the physical shape of the inner track 51 when the user rotates the shield 40, the shape determines the axial movement of the shield 40. When the user rotates the shield 40 in the clock-wise direction as shown by the arrow “A” provided on the shield 40, the shield 40 step-by-step follows the movement indicated by the pattern of positions (a, b, c, d, e) indicated by the arrows marked “B” in figure 6.

The inner track 51 is preferably moulded or otherwise engraved into the inner surface of the housing as illustrated in figure 4. However, to better visualize the principle, the outer layer of the housing is in figure 6 shown with dotted lines thereby emphasising the inner track 51

The housing 50 is further provided with a window 53 through which indicia 42 provided on the shield 40 can be viewed. As will be explained, the user is required to rotate the shield 40 between each injection and the relevant number of each individual injection are thus shown in the window 53. Further, the needle unit 1 can be structured such that it can only be used a specific number of times. In the disclose example this number is 8 times i.e. “0” plus “1” through “7” (see e.g. fig. 8B).

The housing 50 which is also disclosed in the figures 7A-B-C is on an inner surface provided with one or more bayonet protrusions 52 which can engage bayonet tracks provided on the injection device. Alternatively, a threaded connection or a luer coupling could be used.

Further, the housing 50 is internally provided with an internal bridge-like structure 54 which has a number of distally pointing uprights 55 pointing in the distal direction. In the disclosed example four such distally pointing uprights 55 are disclosed. Each upright 55 is provided with a sloped surface 56 which guides the hub 30 as will be explained. In the centre line “X”, the bridge-like structure 54 is provided with an opening 57 through which the needle cannula 10 can move.

In figure 7C, the inner track 51 in the inner surface is shown partly with dotted lines when viewing in perspective from a distal position.

Figure 8A-B-C discloses the needle shield 40. The outer surface is as explained provided with a number of radial protrusions 41 which operates in the inner track 51. Further an arrow “A” and a number of indicia 42 are provided on the outer surface. On the inner surface a number of inwardly pointing protrusions 43 are provided, the use of which will be explained later. Further, the inner surface is provided with a compartment 45 for securing the solid plug 20. The solid plug 20 is preferably glued or press-fitted into the compartment 45 such that the solid plug 20 rotates together with the needle shield 40. The distal end of the needle shield 40 is provided with an opening 46 through which the needle cannula 20 can move.

The needle hub 30 is disclosed in the figures 9A-B-C. On the outer periphery the needle hub 30 is provided with two different kinds of outwardly pointing protrusions 31 , 32. One having a short axial length (numbered 31) and one having a longer axial length (numbered 32). In the disclosed example four of each protrusion 31 , 32 are provided. However, any suitable number can be provided.

Proximally, the hub 30 is provided with a number of proximally pointing uprights 35 which each has a sloped surface 36. These proximally pointing uprights 35 abut against the distally pointing uprights 55 provided inside the housing 50. In the disclosed example four proximally pointing uprights 35 are provided on the hub 30 to match the four uprights 55 in the housing 50.

The centre of the hub 30 is provided with an opening 33 in which the needle cannula 20 is attached such that the needle cannula 20 follows all movements of the hub 30, both translational and rotational.

The relationship between the hub 30 and the housing 50 are disclosed in figure 10A-B, however, the major part of the housing 50 has been visually cut away such that only the centre part of the bridge-like structure 54 is visible.

As seen in figure 10A, the sloped surface 36 on the proximal uprights 35 on the hub 30 abut against the sloped surfaces 56 on the distal uprights 55 provided in the housing 50. Further, the hub 30 is pressed against the housing by the compression spring 80 as realized from figure 5.

As also seen in figure 10A, the distal tip 12 of the needle cannula 10 is parked inside the solid plug 20. In figure 10B, the hub 30 has been rotated clockwise as indicated by the arrow “C” and due to the abutment between the sloped surfaces 36, 56, the hub 30 is forced to move helically in the distal direction as indicated by the arrow “D”. The distal tip 12 of the needle cannula 10 is henceforth moved further into solid plug 20 and even out of the solid plug 20. During this movement the distal tip 12 of the needle cannula 10 diverts more and more from the centre axis “X” as disclosed in figure 1.

The movement of the hub 30 in the distal direction happens against the bias of the compression spring 80 which can be understood from figure 5. As the hub 30 is forced to rotate, the needle cannula 10 follows this rotation and thus rotates around its own centre axis which in the disclosed example is the same as the centre axis “X”.

In the following the movement of the shield 40 in relation to the housing 50 will be explained. As disclosed in figure 6, the radial protrusions 41 are movable along the arrow “B” between a number of different positions identified as “a”, “b”, “c”, “d” and “e”. The pattern of movement is as follows; When the needle unit 1 is delivered to the user as disclosed in figure 11A-B, the radial protrusion 41 is in position “a” (figure 6) and the number zero is visible in the window 53. In this position it is not possible to move the shield 40 in the proximal direction as at least some of the inwardly pointing protrusions 43 inside the shield 40 are positioned aligned with the long protrusion 32 on the hub 30 which thus hinders the shield 40 from movement in the proximal direction. This is best seen in figure 11C in which figure the outer contour of the shield 40 is shown with dotted line and the outer part of the housing 50 is cut away. If the user, in this position, try to move the shield 40 in the proximal direction the inwardly pointing protrusion 43 will abut against the long protrusion 32 on the hub 30 as seen in figure 11C.

In order to get the needle unit 1 ready to perform an injection the user is required to rotate the shield 40 in the clockwise direction following the direction of the arrow “A” on the shield 40. This is disclosed in figure 12A-B. As the radial protrusion 41 moves from position “a” towards position “b”, the inwardly pointing protrusion 43 follows this rotation and moves helically in the proximal direction due to the shape of the track 51. This movement is indicated by the arrow “E” in figure 12B. In this figure, the outer contour of the shield 40 is shown with dotted lines and the outer part of the housing is cut away.

The helical movement of the shield 40 following the track 51 makes the inwardly pointing protrusion 43 abut the short protrusion 31 on the hub 30 and forces the hub 30 to rotate. The rotation of the hub 30 is transferred to a similar rotation of the needle cannula 10. The result is thus that the needle cannula 10 and the shield 40 including the solid plug 20 rotate together and there is no rotational stress applied between the solid plug 20 and the needle cannula 10.

As the hub 30 rotates, the sloped surfaces 36, 56 makes the hub 30 move in the distal direction as previously explained and shown in figure 10B. This movement moves the distal tip 12 of the needle cannula 10 through the solid plug 20 as disclosed in figure 13A-B and positions the distal tip 12 of the needle cannula 10 in the opening 46 in the shield 40. As especially seen in figure 13B, the hub 30 has moved a small distance “W’ in the distal direction. This distance is determined by the degree of the sloped surfaces 36, 56. When the radial protrusion 41 is in the position marked “b” in figure 6, the distal tip 12 of the needle cannula 10 has moved fully through the solid plug 20 and is located off the centre line “X” as explained in figure 1 and inside the opening 46. With the needle cannula 10 in this position an injection is ready to be performed. In this position an injection can be performed as the inwardly pointing protrusion 41 is able to slide translational in the linear part of the track 51.

During injection as disclosed in figure 14A-B, the shield 40 is pushed against the skin of the user and moves in the proximal direction as indicated by the arrow “I” in figure 14A. The inwardly pointing protrusion 41 thus moves towards the position “c”. At the same time the compression spring 80 applies a force onto the hub 30 urging the hub 30 in the proximal direction. However, the hub 30 is unable to rotate back due to the engagement between the short protrusion 31 and the inwardly pointing protrusion 43 inside the shield 40. The shield 40 is kept non-rotatable as the radial protrusion 41 is following the translational part of the track 51.

Figure 15A-B discloses the situation wherein the shield 40 is fully compressed and the radial protrusion 41 is in position “c”. When the shield 40 has reached this position, the dose to be injected is typically released. In this fully compressed position, in which the shield 40 is pushed in the proximal direction against the bias of the compression spring 80, the inwardly pointing protrusion 43 slides out of its engagement with the short protrusion 31. As seen in figure 14B there is such an engagement but in figure 15B, the short protrusion 31 is released from the inwardly pointing protrusion 43 and the hub 30 rotates in the counter clock-wise direction due to the sloped surfaces 36, 56. This is indicated by the arrow “F” in figure 15B.

When moving from position “a” to position “b” both the shield 40 including the solid plug 20 and the hub 30 including the needle cannula 10 rotates together (“E” in figure 12B) such that no rotational stress is applied onto the needle cannula 10. However, during injection, from “b” to “c”, the shield 40 including the solid plug 20 is non-rotational due to the engagement between the radial protrusion 41 and the linear part of the track 51 whereas the hub 30 including the needle cannula 10 rotates back in the counter clock-wise direction (following “F” in figure 15B). This relative rotation between the solid plug 20 and the needle cannula 10 thus rotational moves the needle cannula 10 to a new angular position. Next time an injection is performed, the needle cannula 10 will move through the solid plug 20 in this new angular position. During the rotational movement of the hub 30 a rotational stress is applied onto the needle cannula 10 however as the distal tip 12 is out of the solid plug 20 and inserted into the skin of the user, the needle cannula 10 is in a better position to obtain such rotational stress. Figure 16A-B discloses the situation where the needle cannula 10 is fully retracted from the skin of the user. The inwardly pointing protrusion 43 has slided translational into the space between the short protrusion 31 and the long protrusion 32 and the radial protrusion 41 has moved back into the position marked “b” in figure 6.

In this position, the injection is finished, and the user can remove the shield 40 from the skin of the user. As seen in figure 16A-B, the distal tip 12 of the needle cannula 10 remains positioned in the opening 46 in the shield 40.

When the user has removed the shield 40 from the skin, the needle unit 1 is locked by rotating the shield 40 following the arrow “G” shown in figure 17A-B such that the radial protrusion 41 moves from the position “b” to the position “d” (figure 6).

During this rotation, the inwardly pointing protrusion 43 acts on the long protrusion 32 such that the hub 30 is also rotated whereby the hub 30 moves slightly in the distal direction as best seen in figure 17B.

Once the radial protrusion 41 is in position “d” (figure 6), the compression spring 80 urges the shield 40 in the distal direction following the arrow “H” as disclosed in figure 18A-B. This instantly moves the radial protrusion 41 from “d” to position “e”. During the translational movement of the shield 40, the inwardly pointing protrusion 43 slides out of engagement with the long protrusion 32 where after the hub 30 rotates back to its initial position as indicated by the arrow “J” in figure 18B.

This closed position following thereafter and disclosed in figure 19A-B is the same as the position disclosed in figure 11A-B-C with the difference that now the indicia “1” appears in the window 53 indicating that one injection has been performed.

The above described cycle can hereafter be performed an unlimited number of times. However, the track 51 is preferably provided with an end stop such that the shield 40 can be limited to rotate a little less than 360 degrees; meaning that the number of cycles which can be performed is limited to the number indicated by the indicia 42. It is also possible to provide a different stop in the needle unit 1 limiting the number of possible cycles. 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 subject matter defined in the following claims.

Claims

CLAIMS:

1. An injection needle assembly (1) comprising a base part (50) connectable to an injection device and having a centre axis (X), a needle shield (40) axially movable along the centre axis (X) from a first position to a second position, a resilient means (80) disposed between the base part (50) and the needle shield (40) for urging the needle shield (40) distally into the first position, a needle cannula (10) extending along the centre axis (X) and having a distal part with a grinded distal tip (12), and a solid pierceable cleaning plug (20) for cleaning at least the distal tip (12) of the needle cannula (10) between injections and wherein the solid pierceable cleaning plug (20) is carried by the needle shield (40),

Characterized in that, the needle cannula (10) and the solid pierceable cleaning plug (20) are arranged to be rotatable in relation to each other between injections.

2. An injection needle unit according to claim 1 , wherein the solid pierceable cleaning plug (20) comprises a polymer containing an antibacterial additive.

3. An injection needle unit according to claim 1 or 2, wherein the solid pierceable cleaning plug (20) is secured to the needle shield (40) to follow all movement of the needle shield (40).

4. An injection needle unit according to claim 1 , 2 or 3, wherein the needle shield (40) is rotatable in relation to the base part (50).

5. An injection needle unit according to claim 4, wherein a track (51) and protrusion (41) interface are provided between the base part (50) and the needle shield (40) such that the needle shield (40) is guided in relation to the base part (50) when rotated.

6. An injection needle unit according to any of the previous claims wherein the needle cannula (10) is non-rotatably secured to a needle hub (30)

7. An injection needle unit according to claim 6, wherein the needle hub (30) is secured to the base part (50).

8. An injection needle unit according to claim 6, wherein the needle hub (30) is rotatably in relation to the base part (50).

9. An injection needle unit according to claim 8, wherein the needle hub (30) is urged against the base part (50) by the resilient means (80) and the needle hub (30) abuts the base part (50) through sloped flanges (36, 56).

10. An injection needle unit according to claim 9, wherein the needle shield (40) on an inner surface is provided with a number of protrusions (43) engaging protrusions (31 , 32) provided on the needle hub (30) such that the needle hub (30) is rotatable by the needle shield (40).

11 . A prefilled injection device carrying a needle unit (1) according to any of the claims 1 to 9.

12. A prefilled injection device according to claim 10, wherein the needle unit (1) is releasably connected to the injection device.

13. A prefilled injection device according to claim 10, wherein the needle unit (1) is permanently connected to the injection device.