Needle assembly

Abstract

An injection assembly comprising a cartridge (100, fig. 2) comprising a main body 102 defining a medicament chamber 104 containing a medicament, and an opening 110 at a forward end sealed by a septum 116. A needle assembly 300 comprises a needle 302 having an insertion end 308 for insertion into a patient, and a piercing end 310 configured to pierce the septum in use and bring the interior channel of the needle into contact with the medicament. A needle hub 304 is coupled to the needle, and a housing 306 is coupled to the hub, the piercing end of the needle is within the housing and the housing is configured for attachment with the cartridge. A resiliently deformable portion is configured to provide a seal between the cartridge and the housing when they are attached.

Description

Technical field The invention relates to a needle assembly for attachment to a cartridge. Background Injection devices are used to deliver medicament(s) to a patient by injection. In such devices, which may comprise manual devices or auto-injectors, the medicament to be dispensed to the patient may be contained within a syringe. A syringe generally comprises a barrel within which the medicament is contained, and a needle fixed to the barrel at a forward end thereof, through which the medicament can be expelled. As an alternative to a syringe, the medicament may be contained within a cartridge. Cartridges do not comprise a needle integrally fixed thereto. Typically, cartridges comprise a septum, which seals an open forward end of the cartridge to retain the medicament within the cartridge. The septum may be secured to the cartridge by a crimp and may typically be made of an elastomeric / deformable material. The cartridge may be configured for attachment to a needle assembly. The septum is piercable, or otherwise breakable / releasable, to allow the medicament to be dispensed from the cartridge and into the patient, via the needle assembly. Such needle assemblies may comprise needles comprising a forward tip for insertion into the patient, and a rearward tip, which is configured to pierce the septum to allow the medicament to be dispensed from the cartridge. Cartridges provide a number of advantages over syringes. In particular, cartridges may be available in larger standard sizes than the standard pre-filled syringe sizes. Cartridges may therefore be used where larger volumes (e.g. over 2.25ml) of medicament need to be stored and dispensed. Furthermore, some medicaments may cause a reaction with the needle (which is typically made of stainless steel), and for such medicaments, it is not suitable for the needle to be in contact with the drug for long periods of time prior to use of the drug delivery device. Pre-filled syringes, which comprise needles, may therefore not be suitable for use with such medicaments. While cartridges offer a number of advantages over syringes, because the needle assembly is separate to the cartridge, and needs to be attached thereto, there exists a greater challenge in ensuring the sterility of the drug path from the cartridge and to the patient via the needle assembly. Embodiments of the present invention are intended to address at least some of the abovementioned problems. Summary According to the invention in a first aspect, there is provided a needle assembly for attachment to a cartridge comprising a main body defining a medicament chamber containing a medicament, and an opening at a forward end thereof through which the medicament can be dispensed, the opening sealed by a septum, the needle assembly comprising: a needle comprising an insertion end for insertion into a patient and a piercing end configured, in use, to pierce the septum of the cartridge to bring an interior channel of the needle into fluid communication with the medicament chamber; a needle hub coupled to the needle; a housing coupled to the needle hub, wherein the piercing end of the needle is within the housing, and wherein the housing is configured for attachment to the cartridge; and a resiliently deformable portion configured to provide a seal between the housing and the cartridge. The seal preferably acts to seal the piercing end of the needle within the housing. Optionally, the resiliently deformable portion defines part of the housing. Optionally, the resiliently deformable portion defines a cartridge receiving channel configured to receive at least a portion of the cartridge therein. Optionally, the cartridge receiving channel is defined by sidewalls of the resiliently deformable portion, the sidewalls deformable to accommodate the at least a portion of the cartridge within the cartridge receiving channel. The cartridge receiving channel may be defined by an inner surface of the sidewalls of the resiliently deformable portion. Optionally, the cartridge receiving channel may be substantially cylindrical. Optionally, the cartridge receiving channel is configured to form an interference fit with the at least a portion of the cartridge to be received therein. Optionally, the resiliently deformable portion is substantially cylindrical. Optionally, the resiliently deformable portion defines a rearward portion of the housing. Optionally, the housing further comprises a substantially rigid portion, and wherein the needle hub is coupled to the substantially rigid portion. Optionally, the substantially rigid portion of the housing defines a forward portion of the housing. Optionally, the needle assembly further comprises a seal disposed between the needle hub and the substantially rigid portion of the housing. Optionally, the resiliently deformable portion further defines a needle hub receiving channel within which the needle hub is received. Optionally, the needle hub receiving channel is defined by sidewalls of the resiliently deformable portion, the sidewalls deformable to form a seal between the needle hub and the housing. The needle hub receiving channel may be defined by an inner surface of the sidewalls of the resiliently deformable portion. Optionally, the needle hub receiving channel may be substantially cylindrical. Optionally, the needle assembly further comprises an outer sleeve, wherein the sidewalls defining the needle hub receiving channel are held in compression between the outer sleeve and the needle hub. Optionally, the outer sleeve is further configured to hold the sidewalls of the cartridge receiving channel in compression between the outer sleeve and the cartridge, when the at least a portion of the cartridge is received within the cartridge receiving channel. Optionally, the resiliently deformable portion comprises an O-ring. According to the invention in a further aspect, there is provided an assembly for use in an injection device, the assembly comprising: a cartridge comprising a main body defining a medicament chamber containing a medicament, and an opening at a forward end thereof through which the medicament can be dispensed, the opening sealed by a septum; and a needle assembly comprising: a needle comprising an insertion end for insertion into a patient and a piercing end configured, in use, to pierce the septum of the cartridge to bring an interior channel of the needle into fluid communication with the medicament chamber; a needle hub coupled to the needle; a housing coupled to the needle hub, wherein the piercing end of the needle is within the housing; and a resiliently deformable portion, wherein the housing is attached to the cartridge and the resiliently deformable portion forms a seal between the cartridge and the housing. The seal preferably acts to seal the piercing end of the needle within the housing. Optionally, the resiliently deformable portion defines part of the housing. Optionally, the resiliently deformable portion defines a cartridge receiving channel within which a portion of the cartridge is received. Optionally, the cartridge further comprises a neck defining the opening, the neck comprising smaller outer dimensions than outer dimensions of the main body, and wherein the neck of the cartridge is received within the cartridge receiving channel. Optionally, the septum is clamped to the neck of the cartridge by a tubular crimp, and an outer surface of the tubular crimp engages an inner surface of the resiliently deformable portion, the inner surface defining the cartridge receiving channel. The inner surface may be an inner surface of deformable sidewalls of the resiliently deformable portion, the inner surface defining the cartridge receiving channel. Optionally, outer dimensions of the housing are smaller than outer dimensions of the main body. Optionally, at least a portion of the main body of the cartridge is received within the cartridge receiving channel. Optionally, the piercing end of the needle is separated from the medicament chamber in a pre-use position by the septum. Brief description of drawings Figure 1 shows a perspective view of an exemplary cartridge; Figure 2 shows a cross-section view of the exemplary cartridge of Figure 1; Figure 3 shows a perspective exemplary needle assembly; Figure 4 shows a cross-section view of the exemplary needle assembly of Figure 3; Figure 5 shows a perspective view of an exemplary needle hub and needle; Figure 6 shows a cross-section view of an exemplary needle assembly attached to a cartridge; Figure 7 shows a cross-section view of an exemplary needle assembly attached to a cartridge; and Figure 8 shows a cross-section view of an exemplary needle assembly attached to a cartridge. Detailed description Generally disclosed herein are needle assemblies configured for attachment to a cartridge. The exemplary needle assemblies disclosed herein comprise a double-ended needle comprising an insertion end configured for insertion into a patient to perform an injection, and a piercing end configured to pierce a septum of a cartridge to bring an interior channel of the needle into fluid communication with a medicament contained within the cartridge. The exemplary needle assemblies disclosed herein further comprise a housing within which the piercing end of the needle is located, and which is configured for attachment to the cartridge. Exemplary needle assemblies comprise a resiliently deformable portion, which may form part of the housing, configured to form a seal with the cartridge when the housing is attached to the cartridge. The resiliently deformable portion therefore acts to seal the piercing end of the needle within the housing, preventing contaminants from entering the housing through the point of attachment between the needle assembly and the cartridge. Thus, once the needle assembly is attached to the cartridge, the piercing end of the needle is enclosed in a sterile chamber at least partially defined by the housing, resiliently deformable portion and the cartridge. Assuming that the cartridge and the needle assembly have been assembled in sterile conditions, the piercing end of the needle therefore remains sterile until use of the cartridge and needle assembly in an injection device, to perform an injection. Furthermore, the piercing end of the needle remains within the sterile chamber (i.e. the septum remains unpierced) until an injection is desired to be performed, and therefore the needle is not in contact with the medicament contained within the cartridge during transport and / or storage of the needle assembly and cartridge / injection device, preventing a potential reaction between the medicament and the needle. As used herein, the terms "forward" and "front" refer to the patient facing end of the needle assembly or component thereof. In other words, the front end of the needle assembly is the end proximal to the site into which the needle is inserted during use. Likewise, the term "rear" refers to the non-patient end of the needle assembly or component thereof. In other words, the term "rear" means distant / distal or remote from the site into which the needle is inserted during use. Further, the term longitudinal is used to encompass a direction along or parallel to a longitudinal axis of the needle assembly. Figure 1 shows a perspective view of an exemplary cartridge 100, and Figure 2 shows a cross-section view through the length of the cartridge 100 shown in Figure 1. The cartridge 100 is generally tubular. The cartridge 100 comprises a main body 102 defining a medicament chamber 104 within which a medicament 106 may be contained. The main body 102 is substantially cylindrical. The cartridge 100 further comprises a neck 108 at a forward end thereof. The neck 108 defines an opening 110. As can be seen in Figures 1 and 2, the neck 108 is of reduced diameter compared to the cartridge main body 102. The neck 108 comprises clamping portion 111 defining a clamping surface, which in the exemplary arrangement shown in Figures 1 and 2, comprises a circumferentially extending shoulder 112. The shoulder 112 extends radially outwardly. An intermediate neck portion 113 extends between the main body 102 of the cartridge and the clamping portion 111 of the neck 108. The intermediate neck portion 113 is of reduced diameter compared to the clamping portion 111 (and the main body 102). The opening 110 is sealed by a septum 116, which may be an elastomeric septum. In the exemplary cartridge 100, the septum 116 comprises an elastomeric disc, which abuts an end face 117 of the neck 108 (and specifically an end face of the clamping portion 111 of the neck 108). The septum 116 is held in compression against the end face 117 by a clamping element, which is the exemplary arrangement shown in Figures 1 and 2, comprises a tubular crimp 118. The crimp 118 comprises a tubular sheet of material, preferably aluminium or another ductile metal, which locates around the neck 108 (and specifically the clamping portion 111 of the neck 108) and the septum 116. A first end of the tubular crimp is bent inwards over the septum 116, and a second end of the tubular crimp is bent inwards over the clamping surface (e.g. the shoulder 112) of the neck 108. In this way, the septum 116 is held in compression between the first end of the tubular crimp 118 and the end face 117 of the neck 108. At least a portion of the septum 116 is exposed, i.e. not covered by the crimp 118, to allow the septum 116 to be pierced by a needle to bring the medicament 106 into fluid communication with an interior channel of the needle during use of the cartridge 100 in an injection operation. A bung 120 may be received within the main body 102 of the cartridge 100. The bung 120 closes the rearward end of the medicament chamber 106. As such, the medicament 106 is sealed within the medicament chamber 104 by the septum 116 at a forward end of the cartridge 100 and the bung 120 at a rear end of the cartridge 100. Figure 3 shows a perspective view of an exemplary needle assembly 300, and Figure 4 shows a cross-section view through the length of the needle assembly 300. The needle assembly 300 is attachable to a cartridge, such as the cartridge 100 shown in Figures 1 and 2. The skilled person will understand however, that the needle assembly 300 may also be attached to cartridges of different configurations to those shown in Figure 1. The needle assembly 300 comprises a needle 302, a needle hub 304 and a housing 306. The housing 306 is configured for attachment to the cartridge 100. The needle 302 comprises an insertion end 308 (or an insertion needle tip) and a piercing end 310 (or a piercing needle tip). An internal channel extends between the insertion end 308 and the piercing end 310, through which a fluid may flow, such as a medicament. As will be described in more detail below, the piercing end 310 of the needle 302 is located within the housing 306. The needle 302 is fixed to a needle hub 304 such that movement of the needle hub 304 causes corresponding movement of the needle 302. The needle hub 304 may be fixed to the needle using an adhesive, although the skilled person will appreciate that other fixing means may be used. Figure 5 shows a perspective view of the needle 302 and the needle hub 304 in isolation from the remaining components of the needle assembly 100. As shown in Figure 5, an insertion portion 312 of the needle, comprising the insertion end 308, extends from a first (forward) end of the needle hub 304, and a piercing portion 314 of the needle 302, comprising the piercing end 310, extends from a second (rearward) end of the needle hub 302. The needle hub 304 is substantially cylindrical, and in the exemplary arrangement shown, tubular. The skilled person will however understand that alternative cross sections may be used. In the exemplary arrangement shown in Figure 5, the needle hub 304 defines an internal channel through which the needle 302 extends and within which at least a portion of the length of the needle 302 is fixed. The needle hub 304 is coupled to the housing 306, such that the piercing end 310 of the needle 302 is received within the housing 306. In the arrangement shown in Figures 3 and 4, the needle hub 304 is releasably coupled to the housing 306 such that on decoupling, the piercing end 310 of the needle 302 is moveable within the housing 306 from a pre-use position (as shown in Figure 3 and 4), to an injection position. When the needle assembly 300 is attached to a cartridge 100, the piercing end 310 of the needle 302 is separated from the septum 116 of the cartridge 100 in the pre-use position, and pierces the septum 116 when moved towards the injection position. The needle hub 304 comprises coupling features configured to engage corresponding coupling features on the housing 306 to couple the needle hub 304 to the housing 306. As best shown in Figure 4, the coupling features comprise resiliently deformable legs 328a, 328b on the needle hub 304 configured to engage a retention surface 330 on the housing 306. The engagement of the resiliently deformable legs 328a, 328b with the retention surface 330 prevents movement of the needle hub 304 relative to the housing 306 in a rearward direction and retains the piercing end 310 of the needle 306 in the preuse position. A stop surface of the needle hub 304 configured to engage a corresponding stop surface of the housing 306 prevents movement of the needle hub 304 in the forward direction. During use of the needle assembly 100 to perform an injection, the resiliently deformable legs 328a, 328b are deformable to disengage from the retention surface 330 to allow relative movement of the needle hub 304 and the housing to move the piercing end 310 of the needle 302 towards the injection position. The skilled person will appreciate that in alternative arrangements, the resiliently deformable legs may be located on the housing 306 and the retention surface 330 on the needle hub 304. In further arrangements alternative coupling features may be provided, such as screw threads, lug / track arrangements etc. The needle assembly 300 comprises a seal 334 disposed between the needle hub 304 and the housing 306. At least a portion of the needle hub 304 is received within the housing 306 and the seal 334 is disposed between an outer surface of the needle hub 304 and an inner surface of the housing 306. The seal 334 comprises an elastomeric O-ring that locates around the outer surface of the needle hub 304. A gap between the outer surface of the needle hub 304 and the inner surface of the housing 306 is smaller than the radial thickness of the O-ring, such that the O-ring is held in compression between the needle hub 304 and the housing 306. The skilled person will appreciate that alternative seals may be used in alternative arrangements. The housing 306 is substantially cylindrical and tubular, although the skilled person will appreciate that alternative cross-sections may be used. The housing comprises a first (forward) portion 338 to which the needle hub 304 is coupled, and a second (rearward) portion 340 configured for attachment to the cartridge 100. In the embodiment shown in Figures 3 and 4, the first portion is substantially rigid, and the second portion 340 is resiliently deformable. The first and second portions 338, 340 are coupled together and in the exemplary needle assembly 300, each of the first and second portions 338, 340 are substantially cylindrical and tubular, such that a substantially cylindrical and tubular housing 306 is formed. The first and second portions 338, 340 may be integrally formed, or else adhered together. An internal chamber 342 is defined by the housing 306, and in the embodiment of Figures 3 and 4, the internal chamber 342 is defined by inner surfaces of the housing 306 (and specifically, inner surfaces of the first and second portions 338, 340). The piercing end 310 of the needle 302 is received within the internal chamber 342. A forward opening 344 is defined by the housing 304 through which the needle hub 304 is received, and from which the insertion end 308 (and insertion portion 312) of the needle 302 extends. In the exemplary needle assembly 300, the first portion 338 of the housing 306 defines the forward opening 344. The seal 334 is disposed between the needle hub 304 and an inner surface of the first portion 338 to seal the needle hub 304 to the first portion 344 and prevent contaminants from entering the housing 306 through the forward opening 344. The second portion 340 is a resiliently deformable portion comprising resiliently deformable sidewalls 346 configured to contact and engage an outer profile of the cartridge 100 to attach and seal the needle assembly 100 thereto. In other words, the resiliently deformable portion may be a resiliently deformable sleeve (cylindrical or of other cross-section), the sidewalls of which are deformable to locate around an outer profile of the cartridge 100. The resiliently deformable sidewalls 346 comprise an inner surface 348 that defines a cartridge receiving channel 350 and an opening 352. The cartridge receiving channel 350 is configured to receive at least a portion of the cartridge 100 therein, and in the embodiment shown in Figures 3 and 4, the cartridge receiving channel 350 is configured to receive the neck 108 of the cartridge 100 (including the septum 116 and crimp 118 fixed thereto). As such, the cartridge receiving channel 350 is shaped to substantially correspond to an outer profile of the cartridge 100, and specifically an outer profile of the neck 108 of the cartridge 100. The skilled person will appreciate that in alternative arrangements, the cartridge receiving channel 350 may be further configured to receive at least a portion of the main body 102 of the cartridge 100, and that in such arrangements, the cartridge receiving channel 350 is dimensioned and shaped accordingly. The cartridge receiving channel 350 comprises (slightly) smaller dimensions than the outer dimensions of the neck 108 (and crimp 118) such that an interference fit is formed between the resiliently deformable portion and the cartridge 100, when the neck 108 of the cartridge 100 is received within the cartridge receiving channel 350. Typically, cartridges 100 are provided in standard sizes, and so the skilled person will understand that the shape and dimensions of the cartridge receiving channel 350 may be easily adapted depending on the cartridge to be received therein. Due to the interference fit, the resiliently deformable sidewalls 346 are held in a deformed state when the cartridge 100 is received therein, as the cartridge 100 acts to push the inner surfaces 348 of the resiliently deformable sidewalls 346 radially outwardly. As such, the resiliently deformable sidewalls 346 apply a compressive / clamping force to the cartridge, and specifically to the sidewalls of the crimp 118. In this way, the resiliently deformable portion serves to both attach the needle assembly 300 to the cartridge 100 and form a seal with the cartridge 100 that prevents contaminants from entering the internal chamber 342 of the housing 306 through the opening 352. The opening 352 is defined by an inwardly extending lip 354. The opening 352 may be configured to receive the intermediate portion 113 of the neck 108 of the cartridge 100, and may be of slightly smaller dimension than the outer dimension of the intermediate portion 113 of the neck 108 of the cartridge 100 to facilitate an interference fit. The lip 354 defines an abutment surface 356 configured to engage the shoulder 112 of the neck 108 of the cartridge via the crimp 118 (an end of which is bent over the shoulder 112 as described above). The second portion 340, and specifically the resiliently deformable sidewalls 346, may be formed of a resiliently deformable material, such as a rubberised or an elastomer element, or for example, a thermoplastic elastomer. In the exemplary arrangement shown in Figures 3 and 4, the entirety of the second portion 340 (and therefore the entirety of the sidewalls) are formed from a resiliently deformable material, however in alternative arrangements, the sidewalls may comprise a resiliently deformable inner layer configured to contact and engage the cartridge 100. Figure 6 shows the needle assembly 300 attached to the cartridge 100. The neck 108 of the cartridge 100 is received within the cartridge receiving channel 350 of the housing 306, and as described above, is retained therein due to the interference fit between the cartridge receiving channel 350 of the housing 306 and the cartridge 100. In the specific arrangement shown in Figures 1 to 6, the inner surface 348 of the resiliently deformable sidewalls 346 of the housing 306 abut an outer surface of the crimp 118 which is located over the neck 108 of the cartridge 100 (and specifically the clamping portion 111 of the neck 108 of the cartridge 100). Advantageously, because the sidewalls 346 are resiliently deformable, deviations in the outer profile of the crimp 118 (for example, the crimp may not be completely cylindrical) may be accommodated. As can be seen in Figure 6, when the needle assembly 300 is attached to the cartridge 100, the piercing end 310 of the needle 302 is aseptically sealed within the internal chamber 342 of the housing 306 and therefore remains in a sterile environment until the needle assembly 300 is used to facilitate an injection. The internal chamber 342 is sealed at a forward end of the housing 306 by the seal 334 disposed between the housing 306 and the needle hub 304, and at a rearward end of the housing 306 by the resiliently deformable portion of the housing 306 engaging the cartridge 100 to seal the housing 306 thereto. Therefore, assuming that the cartridge 100 and the needle assembly 300 have been assembled in sterile conditions, the piercing end 310 of the needle 302 remains sterile until use of the cartridge 100 and needle assembly 300, in an injection device, to perform an injection. A further advantage provided by the needle assembly 300 is that the piercing end 310 of the needle 302 is sealed within the internal chamber 342 of the housing 306, when the needle assembly 300 is attached to the cartridge 100, outside of the medicament chamber 104. That is, the piercing end 310 of the needle 302 is separated from the medicament 106 by the septum 116. Therefore, the needle assembly 300 can be attached to the cartridge 100, and the resulting assembly can be stored and / or transported without the risk of the medicament reacting with the needle 302. As can be seen in Figure 6, the outer dimensions of the housing 306 are smaller than the outer dimensions of the main body 102 of the cartridge 100. Advantageously therefore, the needle assembly 300 may be attached and sealed to the cartridge 100 without increasing the width of the resulting assembly. A more compact injection device may therefore be achieved. The skilled person will appreciate however that in alternative arrangements, the outer dimensions of the housing 306 may substantially match, or be greater than, the outer dimensions of the main body 102 of the cartridge 100 to which the needle assembly is to be attached. Figure 7 shows a cross-section view of an alternative needle assembly 700 attached to a cartridge 100. Many features of the needle assembly 700 are similar to those described above in respect of the needle assembly 300. As such, a description of these features is not given again here and corresponding reference numerals are used to identify them in Figure 7. Thus, 702 is the needle comprising a piercing end 710 (and an insertion end, not shown in Figure 7), 704 is the needle hub, and 706 is the housing. However, the needle assembly 700 comprises a different sealing arrangement between the needle hub 704 and the housing 706, when compared to the seal 334 provided between the needle hub 304 and the housing 306 of needle assembly 300. The housing 706 attaches to the cartridge 100 as described above in respect of the needle assembly 300, and therefore comprises corresponding features (such as the cartridge receiving channel 750) which are not described again here. In the needle assembly 700 however, the resiliently deformable portion of the housing 706 further comprises a needle hub receiving channel 760 within which at least a portion of the needle hub 704 is received. The resiliently deformable portion may therefore comprise an open-ended sleeve wherein one end of the sleeve defines the needle hub receiving channel 760 and the other end of the sleeve defines the cartridge receiving channel 750. The needle hub receiving channel 760 is defined by an inner surface 762 of resiliently deformable sidewalls 764. The inner surface 762 may be ribbed (as shown in Figure 7), or in alternative arrangements, may be substantially planar. The needle assembly 700 further comprises an outer sleeve 766. The outer sleeve 766 may be substantially rigid. The outer sleeve 766 locates around the resiliently deformable portion of the housing 706, and specifically the resiliently deformable sidewalls 764 of the needle hub receiving channel 760, so as to hold the resiliently deformable sidewalls 764 in compression against the needle hub 704. A radial thickness of the resiliently deformable sidewalls 764 may be smaller than a gap formed between the needle hub 704 and the outer sleeve 766. As such, the resiliently deformable sidewalls 764 are held in compression between the needle hub 704 and the outer sleeve 766. Therefore, a seal is formed between the needle hub 704 and the housing 706. In the needle assembly 700, the outer sleeve 766 does not surround the resiliently deformable sidewalls 746 defining the cartridge receiving channel 750. This may allow the resiliently deformable sidewalls 746 to be deformed to a greater extent than would be possible if the outer sleeve did surround them, and therefore allows greater variations in the outer profile of the crimp 118 to be accommodated within the cartridge receiving channel 750. Figure 8 shows a cross-section view of a further alternative needle assembly 800 attached to a cartridge 100. Many features of the needle assembly 800 are similar to those described above in respect of the needle assemblies 300 and 700. As such, a description of these features is not given again here and corresponding reference numerals are used to identify them in Figure 8. Thus, 802 is the needle comprising a piercing end 810 (and an insertion end, not shown in Figure 8), 804 is the needle hub, 806 is the housing, and 866 is the outer sleeve. Similarly to the housing 706 of the needle assembly 700, the housing 806 comprises a resiliency deformable portion defining, at a forward end thereof, a needle hub receiving channel 860 within which the needle hub 860 is received, and at a rearward end thereof, a cartridge receiving channel 850 configured to receive at least a portion of the cartridge 100 therein. The cartridge receiving channel 850 however is configured to receive the neck 108 of the cartridge 100 and at least a portion of the main body 102 of the cartridge 100 therein (and is therefore shaped and dimensioned accordingly). As such, the inner surface 848 of the resiliently deformable sidewalls 846 of the cartridge receiving channel 850 is configured to engage (and abut) an outer profile of the crimp 118 and an outer profile of the portion of the main body 102 of the cartridge 100 received therein. The cartridge receiving channel 850 comprises (slightly) smaller dimensions that the outer dimensions of the crimp 118 and the portion of the main body 102 of the cartridge 100 to be received therein, such that an interference fit is formed between the housing 806 and the cartridge 100. In the exemplary needle assembly 800 shown in Figure 8, the outer sleeve 866 locates around the resiliently deformable portion of the housing 806 such that the resiliently deformable sidewalls 864 defining the needle hub receiving channel 860 are held in compression between the outer sleeve 866 and the needle hub 804. Furthermore the outer sleeve locates around at least a portion of the resiliently deformable sidewalls 846 of the cartridge receiving channel 850, such that at least a portion of a length of the resiliently deformable sidewalls 846 is held in compression between the outer sleeve 866 and the cartridge 100, when the needle assembly 800 is attached to the cartridge 100. A radial thickness of the resiliently deformable sidewalls 846 of the cartridge receiving channel 850 may be (slightly) smaller than a gap formed between the outer sleeve 866 and the portion of the cartridge 100 to be received within the cartridge receiving channel 850. As such, the needle assembly 800 is attached to the cartridge 100 and a seal is formed therebetween. The skilled person will appreciate that in alternative arrangements, similarly to the needle assembly 700, the outer sleeve 866 may not surround the resiliently deformable sidewalls 846 defining the cartridge receiving channel 750. At least a portion of the resiliently deformable sidewalls 846 of the cartridge receiving channel 850 may extend from the outer sleeve 866 such that the outer sleeve 866 does not apply a compressive force thereto. The inner surface of the portion of the resiliently deformable sidewalls 846 of the cartridge receiving channel 850 that extend from the outer sleeve 866 may be ribbed (or planar in alternative arrangements). The skilled person will appreciate that in further alternative needle assemblies, the housing may be sealed to the cartridge using alternative resiliently deformable sealing portions / elements. For example, in alternative arrangements, O-rings, grommets, or other resiliently deformable members may be used to form a seal between a housing of a needle assembly and a cartridge to which the needle assembly is to be attached. Such O-rings, grommets, etc. may be configured to locate around the outer diameter of the main body of the cartridge, the outer diameter of the crimp of the cartridge, or may abut the front face of the septum / crimp. The O-rings, grommets etc. may be held in compression against the relevant surface of the cartridge by a component of the housing (e.g. a sidewall of the housing, or else an outer sleeve of the needle assembly) to seal the housing to the cartridge. In further alternative arrangements, the resiliently deformable portion may comprise a resiliently deformable sleeve that surrounds the housing (or at least a portion of the housing) and at least a portion of the cartridge, when the housing is attached to the cartridge, such that the joining / attachment points between the housing and the cartridge are sealed (that is the joining / attachment points are surrounded by the resiliently deformable sleeve). The skilled person will be able to envisage further embodiments of the invention without departing from the scope of the appended claims.

Claims

1. A needle assembly for attachment to a cartridge comprising a main body defining a medicament chamber containing a medicament, and an opening at a forward end thereof through which the medicament can be dispensed, the opening sealed by a septum, the needle assembly comprising:a needle comprising an insertion end for insertion into a patient and a piercing end configured, in use, to pierce the septum of the cartridge to bring an interior channel of the needle into fluid communication with the medicament chamber;a needle hub coupled to the needle;a housing coupled to the needle hub, wherein the piercing end of the needle is within the housing, and wherein the housing is configured for attachment to the cartridge; anda resiliently deformable portion configured to provide a seal between the housing and the cartridge.

2. A needle assembly according to claim 1, wherein the resiliently deformable portion defines part of the housing.

3. A needle assembly according to claim 1 or 2, wherein the resiliently deformable portion defines a cartridge receiving channel configured to receive at least a portion of the cartridge therein.

4. A needle assembly according to claim 3, wherein the cartridge receiving channel is defined by sidewalls of the resiliently deformable portion, the sidewalls deformable to accommodate the at least a portion of the cartridge within the cartridge receiving channel.

5. A needle assembly according to claim 3 or 4, wherein the cartridge receiving channel is configured to form an interference fit with the at least a portion of the cartridge to be received therein.

6. A needle assembly according to any preceding claim, wherein the resiliently deformable portion is substantially cylindrical.

7. A needle assembly according to any of claims 2 to 6, when dependent directly or indirectly on claim 2, wherein the resiliently deformable portion defines a rearward portion of the housing.

8. A needle assembly according to any of claims 2 to 7, wherein the housing further comprises a substantially rigid portion, and wherein the needle hub is coupled to the substantially rigid portion.

9. A needle assembly according to claim 8, wherein the substantially rigid portion of the housing defines a forward portion of the housing.

10. A needle assembly according to claim 8 or 9, further comprising a seal disposed between the needle hub and the substantially rigid portion of the housing.

11. A needle assembly according to any of claims 2 to 10, wherein the resiliently deformable portion further defines a needle hub receiving channel within which the needle hub is received.

12. A needle assembly according to claim 11, wherein the needle hub receiving channel is defined by sidewalls of the resiliently deformable portion, the sidewalls deformable to form a seal between the needle hub and the housing.

13. A needle assembly according to claim 12, further comprising an outer sleeve, wherein the sidewalls defining the needle hub receiving channel are held in compression between the outer sleeve and the needle hub.

14. A needle assembly according to claim 13, when dependent directly or indirectly on claim 4, wherein the outer sleeve is further configured to hold the sidewalls of the cartridge receiving channel in compression between the outer sleeve and the cartridge, when the at least a portion of the cartridge is received within the cartridge receiving channel.

15. A needle assembly according to claim 1, wherein the resiliently deformable portion comprises an O-ring.

16. An assembly for use in an injection device, the assembly comprising:a cartridge comprising a main body defining a medicament chamber containing a medicament, and an opening at a forward end thereof through which the medicament can be dispensed, the opening sealed by a septum; anda needle assembly comprising:a needle comprising an insertion end for insertion into a patient and a piercing end configured, in use, to pierce the septum of the cartridge to bring an interior channel of the needle into fluid communication with the medicament chamber;a needle hub coupled to the needle;a housing coupled to the needle hub, wherein the piercing end of the needle is within the housing; anda resiliently deformable portion, wherein the housing is attached to the cartridge and the resiliently deformable portion forms a seal between the cartridge and the housing.

17. An assembly according to claim 16, wherein the resiliently deformable portion defines part of the housing.

18. An assembly according to claim 17, wherein the resiliently deformable portion defines a cartridge receiving channel within which a portion of the cartridge is received.

19. An assembly according to claim 18, wherein the cartridge further comprises a neck defining the opening, the neck comprising smaller outer dimensions than outer dimensions of the main body, and wherein the neck of the cartridge is received within the cartridge receiving channel.

20. An assembly according to claim 19, wherein the septum is clamped to the neck of the cartridge by a tubular crimp, and wherein an outer surface of the tubular crimp engages an inner surface of the resiliently deformable portion, the inner surface defining the cartridge receiving channel.

21. An assembly according to claim 19 or 20, wherein outer dimensions of the housing are smaller than outer dimensions of the main body.

22. An assembly according to any of claims 19 to 21, wherein at least a portion of the main body of the cartridge is received within the cartridge receiving channel.

23. An assembly according to any of claims 16 to 22, wherein the piercing end of the5 needle is separated from the medicament chamber in a pre-use position by the septum.21

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