FIG. 17 is a cutaway view of the third preferred embodiment of the safety needle assembly after use and disconnected (detached) from a medical injector;

FIG. 18 is a cutaway view of a fourth preferred embodiment of a safety needle assembly prior to attachment to a medical injector;

FIG. 19 is a cutaway view of the fourth preferred embodiment of the safety needle assembly and attached to a medical injector;

FIG. 20 is a cutaway view of the fourth preferred embodiment of the safety needle assembly and a medical injector performing an injection;

FIG. 21 is a cutaway view of the fourth preferred embodiment of the safety needle assembly after use and disconnected (detached) from a medical injector;

FIG. 22 is a cross section of a tubular housing, a needle and a needle mount of a fifth embodiment of a safety needle assembly with the needle in the operative position;

FIG. 23 is a cross section of the tubular housing, the needle and the needle mount of the fifth embodiment of the safety needle assembly with the needle in the shielding position;

FIG. 24 is a cross section of a tubular housing, a needle and a needle mount of a sixth embodiment of a safety needle assembly with the needle in the operative position;

FIG. 25 is a cross section of the tubular housing, the needle and the needle mount of the sixth embodiment of a safety needle assembly with the needle in the shielding position;

FIG. 26 is a cut away view of a tubular housing, a needle mount, a needle and a shielding sleeve of a seventh embodiment of a safety needle assembly;

FIG. 27 is a cross section of a tubular housing, a needle, a needle mount and a shielding sleeve of an eighth embodiment of a safety needle assembly with the needle in the operative position; and

FIG. 28 is a cross section of the tubular housing, the needle, the needle mount and the shielding sleeve of the eighth embodiment of a safety needle assembly with the needle in the shielding position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Throughout this specification and with reference to the figures, a safety needle assembly 10 is shown and described herein which provides for shielding of a needle 12 on a pen needle assembly 8 specifically on the non-patient (proximal) end but also, in some embodiments, also on the patient (distal) and. As used herein, the term “distal” and/or “forwards” or “forwardly”, and derivatives thereof, refer to the direction generally towards the patient end for use, and the term “proximal” and/or “rearwards” or “rearwardly”, and derivatives thereof, is used to describe the direction away from the patient during use.

As shown in the figures and as will be described, the proximal end of the safety needle assembly attached to a distal end of a medical injector 11. The distal end of the safety needle assembly 10 will be pressed against the skin of patient during an injection and the distal end of the medical injector 11 locates away for the patient.

Throughout the following description of the preferred embodiments of safety device of this invention, the same reference characters are used to identify corresponding parts of the various embodiments.

The present invention may be used with pen injectors and will be described by way of example as being used with a pen injector. Drug delivery devices 8 generally include a medical injector 11 including a dose-adjustment mechanism for setting a dose, for example of insulin, and a pen needle 12 provided on a safety needle assembly 10 for insertion into a patient to allow proper drug administration. The pen comprises a single use needle 12 and is removed and disposed of after each administered dose.

The pen needle 12 is a double ended needle 12 and includes a patient end 14 or distal end comprising a sharp tip for insertion into a patient. The double ended needle 12 also includes a non-patient end 15 or proximal end comprising a sharp tip for insertion into a drug vial or cartridge 16 provided by the pen injector 11. The proximal/non-patient end 15 of the needle will typically have to pierce a rubber seal 18 which may comprise a septum or stopper provided on the end of the vial or cartridge 16 to access the liquid medicament or drug contained within the cartridge. Devices have been developed in the prior art to shield the distal, or patient end of the needle 12 to prevent an inadvertent “needle stick” after use. Even with the distal end 14 being shielded, the proximal, or non-patient end 15 of the needle 12 is exposed after the detachment of the safety needle assembly 10 from the medical injector 11.

With reference to FIG. 1, a safety pen needle assembly 10 and a medical injector 11 are shown in an exploded view and FIG. 4 shows the complete drug delivery device 8 in an assembled configuration. The safety needle assembly 10 generally includes a hub or tubular housing 20, a needle 12, a shielding sleeve 30. The tubular housing 20 includes a body 21 extending in a longitudinal direction from a proximal end 24 to a distal end 22. The proximal end 24 is formed with an open face open and is shaped to receive a portion of the injector 11 to allow the attachment of the safety needle assembly 10 to the injector 11. As will be described below, corresponding attachment features are provided on the tubular housing 20 adjacent to the proximal end 24 formed to cooperate with mounting features provided on a distal end of the injector 11. For example, the mounting features may be threads or a surface configuration, such as a tapered surface for a push-fit mounting, or both. The needle 12 may be of any needle design, particularly of any pen needle design. For the description of the present invention, the term cannula 12 will now be used to specifically refer to the double ended needle of the safety needle assembly 10. The cannula 12 includes a distal end 14 formed for insertion into a patient, and a proximal end 15. As shown in the figures, the distal end 14 of the cannula 12 protrudes distally beyond the distal end 22 of the tubular housing 20. The proximal end 15 of the cannula 12 may be within the interior of the tubular housing 20 adjacent to the proximal end 24, or may protrude/extend proximally from the proximal end 24 (this arrangement is not shown). The cannula 12 is mounted within a needle mount 60 and may be fixed therein using any known technique, such as being adherently fixed to the needle mount 60.

Specific embodiments of the present invention will now be described. As shown in FIG. 1, a drug delivery device 8 in the form of a medical pen or injector pen comprises a safety needle assembly 10 which is arranged, in use, to be attached to the medical injector 11. The medical injector 11 comprises a cartridge 16 containing a medicament/fluid and, in particular, the cartridge 16 contains a volume of liquid medicament.

The cartridge 16 is secured within a housing 17. A plunger assembly (not shown) includes a piston 19 or stopper which is used to force the liquid medicament from the cartridge 16. The cartridge 16 comprises a crimped cap 38 and a rubber seal 18. The rubber seal 18 forms a seal to contain the liquid medicament and is pierceable by a proximal end 15 of a cannula 12 (double ended needle) as will be described in more detail below.

The cartridge 16 locates within the housing 17 and the crimped cap 38 locates within a distal end of the housing 17. The distal end of the housing 17 includes a boss 40 including an aperture 32 provided on a distal end face 39 which, when assembled, aligns with the rubber seal 18 and provides an access window to the rubber seal 18 such that the rubber seal 18 is exposed and accessible through the window.

The present invention provides a safety needle assembly 10 which is attachable to the medical injector 11. The safety needle assembly 10 provides the cannula 12 through which the liquid medicament is delivered from the cartridge 16 to the patient. The cannula 12 comprises a double ended needle having a sharp tip at the patient end (distal end) 14 and also a sharp tip at the non-patient end (proximal end) 15. However, it should be appreciated that the terms needle and cannula are used interchangeably and the present invention may also be suitable for other types of drug delivery devices 8. The present invention is suitable for use with needles or cannulas 12 and aims to prevent needle stick injuries caused by the proximal/non-patient end 15 of the needle or cannula 12.

In order to deliver the liquid medicament, the cannula 12 is held in an operative position. In this operative position, the linear cannula 12 protrudes directly out of the end of the drug delivery device 8 and, specifically, the cannula 12 extends along the (central) longitudinal axis 50 of the tubular housing 20. Accordingly, in this operative position, the cannula 12 is located in a central co-axial position within the tubular housing 20. This co-axial position enables the cannula 12 to protrude perpendicularly from a front face 31 of the needle safety assembly 10.

The safety assembly 10 provides a front face 31 having a central window or aperture 32 through which the cannula 12 projects or is projectable. In the first preferred embodiment, the safety needle assembly 10 is provided with an end cap in the form of a shielding sleeve 30 which includes the central window 32. In the first preferred embodiment, the shielding sleeve 30 or end cap functions as a blocking means in the form of a control member 80 to retain the position of the cannula 12 and to release the cannula 12 as will be described below.

The control member 80 or shielding sleeve 30 is mounted to the tubular housing 20. The control member 80 or shielding sleeve 30 locates over the outer surface 23 of the tubular housing 20 and is retained thereto. However, control member 80 or shielding sleeve 30 is slidably movable in a longitudinal direction relative to the tubular housing 20. The significance of this longitudinal sliding movement will be described later.

The housing 17 of the injector 11 has a distal end providing an external screw thread 36 to engage with an internal screw thread 37 provided on the safety needle assembly 10. Specifically, the proximal end 24 of the tubular housing 20 provides the internal screw thread 37 for attaching the safety needle assembly 10 to the housing 17.

The cannula 12 is secured within a needle mount 60. The needle mount 60 is arranged to be fixed within the tubular housing 20 in order to secure the cannula 12 within the safety needle assembly 10. The needle mount 60 is provided with two axial members in the form of lugs 64, 65 for engagement within two corresponding axial members in the form of recesses 28, 29 provided internally on the tubular housing 20. In particular, the tubular housing 20 defines a rotational axis which may be a fixed rotational axis about which the cannula 12 is able to rotate (or pivot). Such movement is functionally important to the present invention and enables the cannula 12 to rotate from an operative position to a shielding positon. In the shielding positon, the non-patient end 15 of the cannula 12 is shielded to prevent and/or inhibit back end needle stick injuries. As will be described, a fixed rotational axis may be provided by axle elements which are engaged within corresponding recesses to prevent any other relative movement apart from the rotational/pivoting action of the needle mount 60 relative to the tubular housing 20. In alternative embodiments, the rotational/pivoting functionality may be provided by a flexible section such as a live hinge arrangement whereby the rotational axis may not be statically fixed to solely provide rotation about a static rotational axis. The present invention will be described with reference to static rotational axes.

As will be described, the cannula 12 is arranged to rotate (or pivot) about a fixed axis 52 (or fixed point) in the tubular housing 20. In the operative position, the cannula 12 extends along the central longitudinal axis of the tubular housing 20. The fixed axis 52 for rotation extends perpendicularly and intersects the central longitudinal axis 50. The fixed axis 52 extends diametrically across the tubular housing 20 and extends radially from the central longitudinal axis 50. This creates a fixed axis 52 or fixed pivoting point or fixed point of rotation for the cannula 12 which is located on the central longitudinal axis 50.

As mentioned above, the cannula 12 is arranged to rotate about the fixed axis 52 from an operative position in which the cannula 12 extends along the central longitudinal axis 50 to a shielding position in which the cannula 12 extends at an angle to the central longitudinal axis 50. In particular, in the shielding position, the cannula 12 extends in a direction oblique to the central longitudinal axis 50.

Due to the fixed axis 52 and fixed point of rotation for the cannula 12, the movement from the central longitudinal axis 50 to an oblique position causes the non-patient end 15 of the cannula 12 to move towards the internal wall 26 of the tubular member 20. In this position with the non-patient end 15 of the cannula 12 towards and adjacent to the internal wall 26 of the tubular housing 20, the non-patient end 15 is shielded to a greater degree and provides significantly reduced risk of creating a needle stick injury. Furthermore, as a result of the fixed axis 52, the pivoting action of the needle about the fixed point located on the central longitudinal axis 50 means that the non-patient end 15 of the cannula 12 also moves forwardly (in a distal direction) and away from the open end 24 of the tubular housing 20. This movement of the non-patient end 15 of the cannula 12 in a distal direction of the longitudinal axis 50 of the tubular housing 20 thereby increases the distance between the open end 24 of the tubular housing 20 and the non-patient end 15 of the cannula 12. This increases the level of protection afforded by increasing the distance by which a tip of a finger would need to be inserted into the open end 24 of the tubular housing 20 in order to make contact with the non-patient end 15 of the cannula 12. This increased separation distance coupled with the non-patient end 15 also being located adjacent to the wall 26 of the tubular housing 20 provides increased safety for users from needle stick injuries.

The increased safety arises from the arcuate or circumferential travel/movement of the non-patient end 15 of the cannula 12 as will be further described below. The present invention provides a passive safety system which causes the cannula 12 to move from the operative position to the shielding position automatically without any specific intervention or action by the user. In particular, as is the case with normal pen injector systems, detachment of the safety needle assembly 10 from the injector 11 exposes the open end 24 of the tubular housing 20 and potentially the non-patient end 15 of the cannula 12 and thereby creates the opportunity for needle stick injuries at the back end. Accordingly, as will be described below, the present invention provides a system through which the cannula 12 moves to the improved shielding position automatically on detachment of the safety needle assembly 10 from the injector 11. A blocking system is arranged to retain the cannula 12 in the operative position before attachment of the safety needle assembly 10 to the medical injector 11. Furthermore, the blocking system maintains the cannula 12 in the operative position prior to use and before attachment of the safety needle assembly 10 to the injector 11. In particular, before use, the blocking system retains the non-patient end 15 in a piercing position such that the non-patient end 15 is located centrally relative to the periphery of the open end 24 of the tubular housing 20. As the injector 11 is attached to the safety needle assembly 10, the non-patient end 15 of the cannula 12 pierces the rubber seal 18 of the cartridge 16 in order to penetrate into the internal reservoir comprising the liquid medicament. Accordingly, the non-patient end 15 is located co-axially central within the tubular housing 20 in order for the tip 15 to pierce and to locate within the cartridge 16.

The use and operation of the first preferred embodiment of the present invention will now be described with reference to FIG. 1 to FIG. 7. As described above, the drug delivery device 8 comprises the safety needle assembly 10 and the pen injector 11 and these are shown detached, prior to use, in FIG. 2. In this position, the cannula 12 is held in an operative position and, specifically, the non-patient end 15 of the cannula 12 is positioned along the central longitudinal axis 50 of the tubular housing 20.

The cannula 12 is secured within the needle mount 60 which provides two axle lugs 64, 65 on opposing sides. The axle lugs 64, 65 are received within two corresponding recesses 28, 29 in the tubular housing 20 such that the cannula 12 is rotatable about a fixed axis 52 within the tubular housing 20.

The safety needle assembly 10 is attached to the pen injector 11 using the screw threads 36, 37 provided on the end of the pen injector 11 and also on the tubular housing 20. As the safety needle assembly 10 is brought into engagement with the pen injector 11 the non-patient end 15 of the cannula 12 abuts, pierces and then projects through the rubber seal 18. During this attachment, the cannula 12 is held along the central longitudinal axis 50 in order to assist with the smooth movement of the cannula 12 through the rubber seal 18.

Once attached, the non-patient end 15 of the cannula 12 locates within the central reservoir of the cartridge as shown in FIG. 5A and FIG. 5B.

The tubular housing 20 includes spring means in the form of a leaf spring 70 in the form of a resilient finger 72 which projects inwardly from the internal surface 26 of the tubular housing 20. The resilient finger 72 includes a contact tip 74 which contacts or abuts an outer surface of the needle mount body 62 at a position located offset from the fixed axis 52 of rotation defined by the axial members 28, 29, 64, 65. Accordingly, in the operative position, the resilient finger 72 is in a configuration whereby the tip 74 exerts a force, specifically a moment or torque, on the outer surface of the needle mount 60. Accordingly, in the operative position, the resilient finger 72 is not in a neutral position and is in a deflected state relative to the neutral relaxed condition/state/position. In particular, in the operative position, the leaf spring 70/resilient finger 72 is preloaded such that energy is stored within the leaf spring 70/resilient finger 72. This stored energy acts to urge the cannula 12 away from the operative position and away from being aligned with the longitudinal axis of the tubular housing 20. Before assembly of the needle mount 60 within the tubular housing 20, the leaf spring 70/resilient finger 72 is in a neutral state with no stored energy. On mounting of the needle mount 60 within the tubular housing 20, the leaf spring 70/resilient finger 72 is deflected and moved to store energy which acts to urge the needle mount 60 away from the operative position. On release of the cannula 12/needle mount 60 by both the control member 80 and the rubber seal 18, the non-patient end 15 of the cannula 12 locates adjacent to the internal wall 26 of the tubular housing 20. In this configuration, the leaf spring 70/resilient finger 72 would typically not be the neutral position and energy is still stored such that the leaf spring 70/resilient finger 72 continues to press and urge the non-patient end 15 of the cannula 12 against the internal wall 26 of the tubular housing 20.

The needle mount 60 is maintained in the operative position by control means which engages a part of the needle mount 60 and maintains the cannula 12 in the operative positon. In the first preferred embodiment, the blocking means is provided by the shielding sleeve 30 which includes the central aperture 32. The central aperture 32 engages around a front end of the needle mount 60. In addition, the shielding sleeve 30 is secured around the tubular housing 20 and is only able to move longitudinally with respect to the tubular housing 20 in a distal direction. Accordingly, in the set position shown in FIGS. 5A and 5B, the front end of the needle mount 60 is secured within the aperture 32 of the shielding sleeve 30 such that any force exerted by the resilient finger 72 is counteracted and does not cause rotation of the needle mount 60 or cannula 12 about the fixed axis 52.

In this set position, it can be seen that the patient end 14 of the needle protrudes/projects outwardly from the drug delivery device 8 and is thereby able to inject a patient and to deliver the liquid medicament from the pen injector 11. Once the injection has been completed, the shielding sleeve 30 is moved forwardly to a shielding position. The specific details of the arrangement of the front shielding sleeve 30 are not provided in this specification and there are many suitable devices available, for example as described in WO2011/092518. In particular, the shielding sleeve 30 slides in a distal direction longitudinally relative to the tubular housing 20, as shown in FIG. 6. In this position, the needle mount 60 is no longer engaged within the aperture 32 of the shielding sleeve 30 and can no longer prevent the spring means rotating the needle mount 60 about the fixed axis 52. However, the non-patient end 15 of the cannula 12 remains engaged within the rubber seal 18 along the longitudinal axis 50 such that this arrangement still prevents rotation of the needle mount 6040 about the fixed axis 52.

After use the safety needle assembly 10 requires disposal and is, therefore, detached from the medical injector 11 through use of the threaded surfaces 36, 37 to detach and unscrew the safety needle assembly 10. As shown in FIG. 7A, on detachment, the non-patient end 15 of the cannula 12 is withdrawn back through and disengaged from the rubber seal 18 and is therefore no longer held by the rubber seal 18 along the longitudinal axis 50 of the tubular member 20. In this configuration, there is no restraining means preventing rotation of the needle mount 60 due to the exerted torque of the resilient finger 72 and, therefore, the needle mount 60 automatically rotates about the fixed axis 52, as shown in FIGS. 7A and 7B.

Due to the length of the cannula 12 and/or the energy stored in the resilient finger 72, the needle mount 60 rotates about the fixed axis 52 until the non-patient end 15 of the cannula 12 locates adjacent to and, preferably, abuts the internal side wall 26 of the tubular housing 20. As a result of the fixed axis 52 of the needle mount 60, the non-patient end 15 of the cannula 12 moves in a distal direction and circumferentially about the axis 52 in an arcuate direction such that the distance along the longitudinal extent between the non-patient end 15 and the open face 24 of the tubular housing 20 increases. Accordingly, not only does the non-patient end 15 locate adjacent to the internal wall 26 of the tubular housing 20 but the non-patient end 15 is also withdrawn/retracted into the tubular housing 20 which significantly increases the protection afforded from needle stick injuries. Both the sideways, radial movement of the non-patient end 15 and the retraction/withdrawal movement in the distal direction of the non-patient end 15 are performed automatically and simultaneously such that the present invention provides improved passive needle stick protection. Furthermore, in the shielding position, the leaf spring 70 may continue to exert a pivoting/rotating force on the needle mount 60 and this presses the non-patient end 15 of the cannula 12 against the internal wall 26 of the tubular housing 20.

Furthermore, it will be noted that the patent end 14 of the cannula 12 locates in a position which is not aligned with the aperture 32 of the shielding sleeve 30 such that the longitudinal sliding movement of the shielding sleeve 30 would not cause the patient end 14 of the cannula 12 to project through the aperture 32 in order to present a further risk.

Overall, in the first embodiment, the safety needle assembly 10 does not have a separate control member 80 since this functionality is provided by the needle shielding sleeve 30. Briefly, the spring 70 is arranged to urge rotation of the needle mount 60 about an axis generally perpendicular to and intersecting a longitudinal axis 50 of the cannula 12. However, the control member 80 (shown located at a first position relative to the needle mount in FIG. 5A and FIG. 5B) prevents rotation of the needle mount 60. As the safety needle assembly 10 (pen needle) is screwed onto the injector 11 (pen injector), the non-patient end 15 of the needle 12 pierces the rubber seal 18 of the cartridge 16 and enters into the drug reservoir within the pen injector 11. The needle shielding sleeve 30 is already retracted and in the injecting configuration and the drug can now be delivered into the patient. The pen needle 10 is removed from the injection site and the needle shielding sleeve 30 can now be moved forward and locked safely in a needle shielding position automatically. As mentioned above, the mechanism for moving the shielding sleeve is not described herein and a suitable arrangement is provided in WO2011/092518. However, the needle mount 60 cannot rotate (even though the control member 80 is no longer preventing rotation of the needle mount 60) because the non-patient end 15 of the cannula 12 is still inserted into the rubber seal 18 of the pen injector reservoir. When the pen needle 10 is disconnected (detached) from the pen injector 11 the spring 70 can then rotate the needle mount 60 to “safely park” the non-patient end 15 of the cannula 12 so that the pointed end of the cannula 12 abuts against the inside wall 26 of the tubular housing 20.

The operation and use of further preferred embodiments will now be described in relation to FIGS. 8-28.

A second preferred embodiment, as shown in FIG. 8 to FIG. 12, includes a blocking means comprising a control member 180 in the form of an annular component 182 in the form of a disc which is separate from the shielding sleeve 130. In the configuration before use, with the safety needle assembly 110 not having been attached to the pen injector 111, the needle mount 160 is again held in the operative position by the control member 180. As mentioned above, in this embodiment, the control member 180 comprises an annular component 182 or disc with a central aperture 184 which aligns with, and engages, an outer surface 161 of the front portion of the needle mount 160 in a similar way as described above. However, the shielding sleeve 130 of this second preferred embodiment, acts as a shield which protects the patient end 114 of the cannula 112 prior to use. The operation of this embodiment is the same as described above in that the tubular housing 120 is attached to the injector 111 through the use of the screw threads and this causes the non-patient end 115 of the cannula 112 to pierce and penetrate through the rubber seal 118 into the internal volume of the cartridge 116.

FIG. 9 shows the drug delivery device 108 in the set position with the drug delivery device 108 ready for use. The shielding sleeve 130 is slidably movable over the tubular housing 120 in the longitudinal direction. In particular, the shielding sleeve 130 may comprise spring means (not shown) to urge the shielding sleeve 130 to move in a distal direction to the outer position shown in FIG. 9. In order to perform an injection, the front face 131 of the shielding sleeve 130 is pressed against the skin of the patient and the shielding sleeve 130 slidably moves over the tubular housing 120 towards the injector 111. The patient end 114 of the cannula 112 projects through the central aperture 132 provided in the shielding sleeve and into the patient in an injecting configuration On full retraction of the shielding sleeve 130 over the tubular housing 120, the cannula 112 may protrude by a pre-set amount in order to perform the required injection. In this position, the control member 180 (annular component 182) locates adjacent to the front (distal) end of the shielding sleeve 130, as shown in FIG. 10.

Once the liquid medicament has been delivered, the drug delivery device 108 is moved away from the skin of the patient and spring means (not shown) may push the shielding sleeve 130 in a distal direction relatively away from the injector 111 and slidably moves the shielding sleeve 130 over the tubular housing 120 to the used position (not shown) and a locking means locks the shield in the used position (not shown). The control member 180 in the form of the annular component 182 is retained in the outer/distal position adjacent to the distal end of the shielding sleeve 130 through frictional engagement or other latching arrangement. This thereby automatically or passively releases the control member 180 on performing an injection from engagement with the needle mount 160 since the tubular housing 120 comprising with needle mount 160 moves with the injector 111 away from the skin of the patient. Accordingly, in this configuration, the control member 180 no longer retains the cannula 112 in the operative positon. However, the cannula 112 is maintained in the operative position through the engagement of the non-patient end 115 of the cannula 112 with the rubber seal 118. It should be noted that the control member 180 in this embodiment may also provide a visual indication that the injection has been performed correctly and to the correct depth since it is retained at a visible position at the distal end.

As before, the safety needle assembly 110 is now able to be detached from the pen injector 111 through the release of the screw threads 136, 137. Once the non-patient end 115 of the cannula 112 is moved through the rubber seal 118 and is released thereby, the leaf spring 170 in the form of the resilient finger 172 then rotates the needle mount 160 to the shielding position, as shown in FIG. 12. Again, this movement is automatic and provides passive needle stick protection.

In the shielding positon, the non-patient end 115 of the cannula 112 locates adjacent to the internal wall 126 of the tubular housing 120. Furthermore, due to the location of the fixed axis of the movement, the non-patient end 115 of the cannula 112 is withdrawn further into the tubular housing away from the open end 124 to provide significantly greater protection. The axis 52 for movement of the cannula 112 intersects a longitudinal axis of the tubular housing 120 and the point of contact of the leaf spring 170 on the needle mount 160 is arranged to ensure that the non-patient end 115 moves distally and not proximally. Prior to detachment of the safety needle assembly 110 from the medical injector 111, the non-patient end 115 penetrates the rubber seal 118 and this holds the cannula along the longitudinal axis of the tubular housing 120.

A third preferred embodiment is shown in FIG. 13 to FIG. 17. In this embodiment, the blocking means comprises a control member 280 provided by an annular component 282 coupled with a skirt portion 284. The safety needle assembly 210 is provided with a shielding sleeve 230 which provides shielding to the patient end 214 of the cannula 212 prior to use. In this embodiment as shown in FIG. 14, as the safety needle assembly 210 is screwed onto the injector 211, a lower face 285 of the skirt 284 of the control member 280 abuts an end face 239 of the boss 240 of the injector 211 which thereby forces and moves the control member 280 distally or forwardly with respect to the injector and relative to the tubular housing 220. This movement automatically disengages the control member 280 from the needle mount 260. In particular, the needle mount 260 is provided with a collar 266 to aid this disengagement. The collar 266 provides a step surface which abruptly changes the configuration of the control member 280 from the engaged position to the disengaged position and reliably enables the pivoting movement of the needle mount 260. The skirt 284 of the control member 280 is provided with a cutaway portion in order to accommodate the location of the leaf spring 270 (resilient finger 272) on the internal wall 226 of the tubular housing 220.

As described above, the injection is conducted through urging the front face 231 of the shielding sleeve 230 against the patient's skin to cause the patient end 214 of the cannula 212 to project through the aperture 232 and into the patient to the required depth. On completion of the injection, the shielding sleeve 230 is automatically urged to return to the shielding position by a spring mechanism (not shown).

The safety needle assembly 210 is detached from the injector 211 through use of the screw threads 236, 237. The needle mount 260 is now only being held in the operative position through the engagement of the non-patient end 215 of the cannula 212 with the rubber seal 218 such that when removed from the rubber seal 218 the needle mount 260 automatically rotates about the fixed axis 52 to the shielding position. Again, the position of the axis is defined to withdraw the non-patient end 215 of the cannula 212 in a distal direction and continues further into the tubular housing 220 and also cause the non-patient end 215 of the cannula 212 to locate adjacent to the internal wall 226 of the tubular housing 220, as shown in