SAFETY DEVCE FOR A PRE-FILLED SYRINGE AND AN INJECTION DEVICE

Abstract

According to the invention, a safety device for a pre-filled syringe with an injection needle comprises of a support body adapted to mount the pre-filled syringe, a needle shield slidably arranged with respect to the support body, a retention and locking means (M) for retaining and locking the needle shield with respect to the support body in a first and a second advanced position (PA1, PA2) and in a retracted position (PR). The needle shield comprises an annular flange adapted to rest on the skin of the patient receiving an injection. The retention and locking means (M) are arranged at a distal end of the safety device.

Claims

1. A safety device (1) for a pre-filled syringe (2) with an injection needle (2.1) comprising a support body (1.2) adapted to mount the pre-filled syringe (2), a needle shield (1.1) slidably arranged with respect to the support body (1.2), a retention and locking means (M) for retaining and locking the needle shield (1.1) with respect to the support body (1.2) in a first and a second advanced position (PA1, PA2) and in a retracted position (PR), wherein the needle shield (1.1) comprises an annular flange (1.1.1) adapted to rest on the skin of the patient receiving an injection and wherein the retention and locking means (M) are arranged at a distal end of the safety device (1).

2. A safety device (1) according to claim 1, characterized in that the support body (1.2), the needle shield (1.1) and/or the outer body (1.3) is at least partially made from a transparent plastics material.

3. A safety device (1) according to claim 1 or 2, characterized in that the needle shield (1.1) is movable from the first advanced position (PA1) to the retracted position (PR) and further to the second advanced position (PA2), wherein the needle shield (1.1) in the first advanced position (PA1) protrudes the support body (1.2) in the distal direction by a first distance (D1) and the needle shield (1.1) in the second advanced position (PA2) protrudes the support body (1.2) in the distal direction by a second distance (D2), wherein the first distance (D1) is smaller than the second distance (D2).

4. A safety device (1) according to one of the previous claims, characterized in that the retaining and locking means (M) are arranged to releasably retain the needle shield (1.1) in the first advanced position (PA1) in a manner that is releasable by a linear translatory movement of the needle shield (1.1) with respect to the support body (1.2) parallel to a central axis (A) of the safety device (1).

5. A safety device (1) according to one of the previous claims, characterized in that the retention and locking means (M) comprise at least one deflectable resilient arm (1.1.2).

6. A safety device (1) according to one of the previous claims, characterized in that the resilient arm (1.1.2) is arranged with the needle shield (1.1) as one piece and is arranged within the needle shield (1.1.1) so as to shield the resilient arms (1.1.2) from being influenced from the exterior.

7. A safety device (1) according to one of the previous claims, characterized in that the resilient arm (1.1.2) latches to a catching recess (1.2.3) formed to a distal end of the support body (1.2) to releasably retain the needle shield (1.1) in the first advanced position (PA1).

8. A safety device (1) according to one of the previous claims, characterized in that resilient arm (1.1.2) is pre-tensioned and deflected in the radial outward direction when latching to the catching recess (1.2.3) to releasably retain the needle shield (1.1) in the first advanced position (PA1).

9. A safety device (1) according to claim 8, characterized in that the pre-tensioned resilient arm (1.1.2) unbends due to a material memory effect when the needle shield (1.1) is released from being retained in the first advanced position (PA1).

10. A safety device (1) according to claim 7, characterized in that the resilient arm (1.1.2) is stressed and inwardly deflected when the needle shield (1.1) is in the retracted and in the second advanced position (PA2).

11. A safety device (1) according to claim 10, characterized in that at least two of the stressed and inwardly deflected resilient arms (1.1.2) are locked to each other by interlocking elements (1.1.4) of the retaining and locking means (M).

12. A safety device (1) according to claim 11, characterized in that two inwardly deflected resilient arms (1.1.2) that are arranged opposite to each other are locked to each other by two interjacent interlocking elements (1.1.4) arranged opposite to each other in manner that the two inwardly deflected resilient arms (1.1.2) and the two interlocking elements (1.1.4) form an interlocked structure (S) that comprises an essentially ring-shaped cross-section.

13. A safety device (1) according to one of the previous claims, characterized in that the needle shield (1.1) is biased with respect to the support body (1.2) in the distal direction by a spring means (1.4).

14. A safety device (1) according to one of the previous claims, characterized in that the spring means (1.4) comprises a spring arm (1.4.1) made from a plastics material, wherein the spring arm (1.4.1) is attached to the needle shield (1.1) and engages a first ramp (1.2.6) formed to an outer surface of the support body (1.2).

15. An injection device (D) comprising a safety device (1) according to one of the previous claims and a pre-filled syringe (2), wherein the safety device (1) comprises a support body (1.2) adapted to mount the pre-filled syringe (2), a needle shield (1.1) slidably arranged with respect to the support body (1.2), a retention and locking means (M) for retaining and locking the needle shield (1.1) with respect to the support body (1.2) in a first and a second advanced position (PA1, PA2) and in a retracted position (PR), wherein the retention and locking means (M) are arranged at a distal end of the safety device (1).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The present invention will be better understood from the detailed description given in the following. The accompanying drawings are given for illustrative purposes only and do not limit the scope of the present invention.

[0065] FIG. 1 shows a perspective view of an injection device D according to a first embodiment of the invention before use;

[0066] FIG. 2 shows a sectional view of the injection device D according to the first embodiment before use;

[0067] FIG. 3 shows a sectional view of the injection device D according to the first embodiment before a medicament is administered to a patient;

[0068] FIG. 4 shows a sectional view of the injection device D according to the first embodiment with a needle shield retracted in a retracted position;

[0069] FIG. 5 shows a sectional view of the injection device D according to the first embodiment after a medicament has been administered to the patient;

[0070] FIGS. 6A and 6B show two different sectional views of the injection device D according to the first embodiment after removal from the injection site;

[0071] FIG. 7 shows a sectional view of the injection device D according to a second embodiment before use;

[0072] FIG. 8A to 8E illustrate in detail the retention and locking means arranged at the distal end of the safety device 1 according to the first and second embodiment of the invention;

[0073] FIG. 9 shows a perspective view of an injection device D according to a third embodiment of the invention before use;

[0074] FIG. 10 shows a sectional view of the injection device D according to the third embodiment before use;

[0075] FIGS. 11A and 11B show two cross-sections of the needle shield 1.1 according to third embodiment of the invention;

[0076] FIG. 12 shows a sectional view of the injection device D according to the third embodiment before the medicament is administered to a patient;

[0077] FIG. 13 shows the injection device D according to the third embodiment after a medicament has been administered to the patient;

[0078] FIG. 14 shows the injection device D according to the third embodiment in a needle safe state;

[0079] FIG. 15 shows a sectional view of an injection device D according to a forth embodiment of the invention with the needle shield retained in the retracted position;

[0080] FIGS. 16A to 16D illustrate in detail the retention and locking means according to the third and forth embodiment of the invention;

[0081] FIGS. 17A to 17D schematically illustrate possible arrangements of a resilient arm retaining the needle shield relative to the support body.

[0082] Corresponding parts are marked with the same reference symbols in all figures.

DETAILED DESCRIPTION

[0083] FIG. 1 shows a perspective view of an injection device D with a safety device 1 for a pre-filled syringe 2 according to a first embodiment of the invention. The safety device 1 comprises a substantially cylindrical and hollow needle shield 1.1 with an annular flange 1.1.1 arranged at a distal end thereof. The needle shield 1.1 is arranged as a double walled shield with a substantially inner and outer wall. The annular flange 1.1.1 projects radial outwards from the needle shield 1.1. and is adapted to rest on the skin of the patient during the injection. Edges of the annular flange 1.1.1 are rounded for comfort and to avoid injuries. The needle shield 1.1 is slidably arranged with respect to a support body 1.2 that receives and mounts the pre-filled syringe 2.

[0084] Before usage of the safety device 1, the needle shield 1.1 is initially retained in a first advanced position PA1. The needle shield 1.1 in the first advanced position PA1 protrudes the support body 1.2 in a distal direction by a first distance D1.

[0085] An annular bearing surface 1.2.1 is formed to the support body 1.2 that protrudes radial outwards. The annular bearing surface 1.2.1 limits the sliding movement of the needle shield 1.1 with respect to the support body 1.2 in the proximal direction.

[0086] The safety device 1 comprises an essentially cylindrical and hollow outer body 1.3 with an open distal and a closed proximal end. The proximal end of the support body 1.2 is received within the open distal end of the outer body 1.3. The outer body 1.3 is slidably arranged with respect to the support body 1.2 and may slide in a distal direction to substantially receive the support body 1.2 at the end of an injection stroke.

[0087] A circumferential and outwardly protruding support flange 1.3.1 is integrally formed to an outer surface of the outer body 1.3 close to its distal end. The outer body 1.3 is adapted to be gripped and pushed by a user in the distal direction, whereby the support flange 1.3.1 supports the hand of the user performing the injection stroke.

[0088] Preferably, the needle shield 1.1, the support body 1.2 and the outer body 1.3 are made from a plastics material. The needle shield 1.1 may be made from an opaque plastics material to hide an injection needle 2.1 of the pre-filled syringe 2 from the view of a patient throughout the injection. This may help to ease a possible fear of needles of the patient. Alternatively, the needle shield 1.1 may be made from a transparent plastics material, so that the user may visually confirm the correct placement of the injection needle 2.1 and easily insert the injection needle 2.1 into the skin of the patient.

[0089] According to a possible embodiment of the invention, the support body 1.2 is made from a transparent material, so that the content of the pre-filled syringe 2 received within the support body 1.2 is visible. The safety device 1 comprises retention and locking means M arranged at the distal end of the safety device 1. Thus, the retention and locking means do not obstruct the view of the user checking the content of the pre-filled syringe 2.

[0090] FIG. 2 shows a sectional view of the injection device D before use. The injection needle 2.1 of the pre-filled syringe 2 is covered by a needle cap 2.2 that engages a distal tip of a barrel 2.3. Preferably, the needle cap 2.2 is at least partially made from a plastics material like rubber.

[0091] The pre-filled syringe 2 inserted into the support body 1.3 and attached thereto by a mechanical connection engages a proximal barrel collar 2.3.1 of the barrel 2.3.

[0092] An inner cavity 2.3.2 of the pre-filled syringe 2 contains a dose of a medicament or drug. A stopper 2.4 that is connected to a plunger 2.5 fluid-tightly seals a proximal end of the inner cavity 2.3.2. The stopper 2.4 may be moved by pushing the plunger 2.5 in the distal direction to expel the dose of the medicament through the injection needle 2.1. The plunger 2.5 is attached to or abuts an inner surface of the outer body 1.3, so that the plunger 2.5 and the stopper 2.4 connected thereto may be moved by pushing the outer body 1.3 with respect to the support body 1.2 in the distal direction.

[0093] A spring means 1.4 is arranged within the needle shield 1.1 and biases the needle shield 1.1 with respect to the support body 1.2 in the distal direction. According to the first embodiment of the invention, the spring means 1.4 is designed as a compression spring made from a metal. Alternatively, the spring means 1.4 may comprise other suitable means to bias the needle shield 1.1, like, for example, a torsion spring or resiliently deflectable spring arms made from suitable plastics materials.

[0094] The retention and locking means M that releasable retain the needle shield 1.1 in the first advanced position PA1 are arranged at the distal end of the safety device 1. The retention and locking means M comprise a catch 1.2.2 formed to an outer surface of the support body 1.2 and protruding therefrom in a radial outward direction to engage the needle shield 1.1.

[0095] FIG. 3 shows a sectional view of the injection device D after removal of the needle cap 2.2. The retention and locking means M comprise two resilient arms 1.1.2 integrally moulded to the needle shield 1.1 and arranged opposite to each other. The resilient arm 1.1.2 is arranged within the needle shield 1.1 to shield the resilient arm 1.1.2 from exterior influences. In particular, the arrangement of the resilient arm 1.1.2 prevents a person from tampering with the resilient arm 1.1.2 retaining and locking the needle shield 1.1 in various positions. With cross-reference to FIG. 8A, it can be seen that the resilient arms 1.1.2 are radial outwardly deflected and in the pre-tensioned state. The resilient arms 1.1.2 latch to a catching recess 1.2.3 formed into the distal end of the support body 1.2 to releasably retain the needle shield 1.1 in the first advanced position PAL The mechanical connection between the outwardly flexing resilient arm 1.1.2 and the catching recess 1.2.3 may be released by a linear translatory of movement of the needle shield 1.1 with respect to the support body 1.2 parallel to a central axis A of the substantially cylindrical safety device 1, whereby the deflected resilient arm 1.1.2 unbends due to a material memory effect.

[0096] FIG. 4 shows a sectional view of the injection device D before an injection stroke is performed by the user. The needle shield 1.1 is located in a retracted position PR and bears against the annular bearing surface 1.2.1 in the proximal direction. The injection needle 2.1 of the pre-filled syringe 2 protrudes the annular flange 1.1.1 of the needle shield 1.1 in the distal direction. The spring means 1.4 designed as the compression spring is fully compressed and stressed.

[0097] An outward projection 1.2.4 is formed to a proximal end of the support body 1.2 that protrudes radial outwards into a longitudinal recess 1.3.2 formed into an inner surface of the outer body 1.3. Preferably, two outward projections 1.2.4 are formed to opposite sides of the support body 1.2 that are received within respective longitudinal recesses 1.3.2 of the outer body. The longitudinal recess 1.3.2 extends parallel to the central axis A and over a substantial axial length of the outer body 1.3. The outward projection 1.2.4 travels within the longitudinal recess 1.3.2 when the outer body 1.3 is slid with respect to the support body 1.2 to expel the dose of the medicament contained in the pre-filled syringe 2 through the injection needle 2.1. This avoids a relative rotation between the outer body 1.3 and the support body 1.2 during the injection, so that a jamming of these parts 1.2, 1.3 may be prevented.

[0098] Furthermore, a first inward projection 1.3.3 is located at the distal end of the longitudinal recess 1.3.2 that abuts the outward projection 1.2.4 of the support body 1.2. The outward projection 1.2.4 has to overcome the first inward projection 1.3.3 before the outer body 1.3 may travel with respect to the support body 1.2 in the distal direction. The interaction between the inward and outward projection 1.3.3, 1.2.4 generates a resistive force that is larger than a respective required force required to move the needle shield 1.1 from the first advanced position PA1 to the retracted position PR. This ensures that the needle shield 1.1 is in the retracted position PR and the injection needle 2.1 is inserted into the skin of the patient before the outer body 1.3 is pushed distally. Thus, so-called wet injections and a spilling of the medicament before the injection needle 2.1 is inserted into the skin of the patient are avoided.

[0099] FIG. 5 shows a sectional view of the injection device D at the end of the injection stroke. The stopper 2.4 connected to the plunger 2.5 is fully depressed into the inner cavity 2.3.1 of the pre-filled syringe 2. The support body 1.2 is substantially received within the hollow outer body 1.3.

[0100] The resilient arm 1.1.2 of the retention and locking means M is in a mechanical unstressed state and extends essentially parallel to the central axis A of the safety device 1.

[0101] FIGS. 6A and 6B show two different sectional views of the injection device D after removal from the injection site. The sectional plane shown in FIG. 6A extends perpendicularly to the one shown in FIG. 6B. The needle shield 1.1 is located in a second advanced position PA2 and surrounds the injection needle 2.1 after the injection.

[0102] As shown in FIG. 6A, the resilient arm 1.1.2 extends parallel to the central axis A, so that a second engagement of the resilient arm 1.1.2 with the catching recess 1.2.3 is avoided. The resilient arm 1.1.2 may thus pass beyond the catching recess 1.2.3, so that the needle shield 1.1 in the second advanced position PA2 protrudes the support body 1.2 by a second distance D2 that exceeds the first distance D1.

[0103] The needle shield 1.1 is locked to the second advanced position PA2 so that a subsequent exposure of the injection needle 2.1 is prevented. As shown in FIG. 6B, the catch 1.2.2 of the support body 1.2 abuts a second inward projection 1.2.5 formed to an inner surface of the needle shield 1.1 to prevent a proximal movement of the needle shield 1.1 with respect to the support body 1.2.

[0104] FIG. 7 shows a sectional view of an injection device D according to a second embodiment of the invention in a packaged state before the injection device D is used to administer the dose of the medicament contained in the pre-filled syringe 2 to the patient.

[0105] The safety device 1 according to the second embodiment of the invention is similar to the one of the first embodiment in both functionality and design. A needle shield 1.1 of the second embodiment comprises compact dimensions and covers, compared to the needle shield 1.1 of the first embodiment, only a relative small area of the support body 1.2 when arranged in the first advanced position PA1, the second advanced position PA2 or the retracted position PR. In particular when the pre-filled syringe 2 is retained in the support body 1.2 made from a transparent material, the user may clearly view the content of the pre-filled syringe 2 independent of the positioning of the needle shield 1.1.

[0106] The retention and locking means M of the safety device 1 according to the second embodiment of the invention work similar to the retention and locking means M of the first embodiment described before.

[0107] FIG. 8A to 8E illustrate in detail the safety mechanism and the retention and locking means arranged at the distal end of the safety device 1 according to the first and second embodiment of the invention.

[0108] A possible sequence of actions for administering the dose of the medicament to the patient with the injection device D according to the first and second embodiment of the invention is described in the following:

[0109] After removal of the needle cap 2.2 from the distal tip of the barrel 2.3, the injection device D is arranged at the injection site, so that the annular flange 1.1.1 rests onto the skin of the patient. The needle shroud 1.1 is retained in the first advanced position PA1, wherein, as illustrated in FIG. 8A, the needle shroud 1.1 projects from the distal end of the support body 1.2 by the first distance D1. The outer body 1.3 is gripped by the user performing the injection and pushed distally towards the skin surface. As a distal movement of the outer body 1.3 with respect to the support body 1.2 is initially prevented by the interaction of outward projection 1.2.4 with the first inward projection 1.3.3, the needle shield 1.1 is released from the first advanced position and pushed in the proximal direction, as illustrated in FIGS. 8A and 8B. The outwardly deflected resilient arms 1.1.2 disengage the catching recesses 1.2.3 and unbend due to a material memory effect. The resilient arm 1.1.2 now extends straight and substantially parallel to the central axis A of the safety device 1.

[0110] As illustrated in FIG. 8C, the needle shield 1.1 is moved further in the proximal direction towards the retracted position PR shown in FIG. 8D, whereby the injection needle 2.1 is inserted into the skin of the patient.

[0111] After the needle shield 1.1 reached the retracted position PR pushing the outer body 1.3 in the distal direction causes the outward projection 1.2.4 to overcome the first inward projection 1.3.3, whereby the outer body 1.3 is released, so that the outer body 1.3 may move in the distal direction. Simultaneously, the stopper 2.4 connected to the outer body 1.3 via the plunger 2.5 depresses into the inner cavity 2.3.2, whereby the dose of the medicament contained in the inner cavity 2.3.2 is expelled through the injection needle 2.1 and disposed beneath the skin of the patient.

[0112] When the stopper 2.4 is fully depressed into the inner cavity 2.3.2, the injection device D is removed from the injection site. The spring means 1.4 relax and move the needle shroud 1.1 to the second advanced position PA2 shown in FIG. 8E. The resilient arm 1.1.2 passes beyond the catching recess 1.2.3, so that the needle shroud 1.1 projects from the support body 1.2 by the second distance D2 that is larger than the first distance D1.

[0113] Even if the injection is aborted before the stopper 2.4 reaches the distal end of the inner cavity 2.3.2 and the medicament is only partially administered, needle safety is still provided upon removal of the injection device D from the injection site. The needle shield 1.1 is driven to the second position PA2 shown in FIG. 8E to cover the injection needle 2.1 after the medication has been partially delivered.

[0114] FIG. 9 shows an injection device D according to a third embodiment of the invention in a perspective view before use. The needle shield 1.1 of the third embodiment is biased in the distal direction by spring means 1.4 that comprise a plurality of spring arms 1.4.1 made from a resilient plastics material. A plurality of longitudinal apertures 1.1.3 corresponding to the spring arms 1.4.1 are formed into the needle shield 1.1. The longitudinal aperture 1.1.3 allows for a deflection of the spring arm 1.4.1 in the radial outward direction.

[0115] FIG. 10 shows a sectional view of the injection device D according to the third embodiment before use. The spring arms 1.4.1 are attached to a distal end of the needle shield 1.1. A proximal end of the spring arm 1.4.1 engages a first ramp 1.2.6 formed to the outer surface of the support body 1.2. During the injection, the proximal end of the spring arm 1.4.1 travels along the first ramp 1.2.6, whereby the spring arm 1.4.1 is deflected outwardly and stressed to bias the needle shield 1.1 with respect to the support body 1.2 in the distal direction.

[0116] The resilient arm 1.1.2 of the retention and locking means M latches to the catching recess 1.2.3 to releasably retain the needle shield 1.1 in the first advanced position PA1. The resilient arm 1.1.2 is not pre-tensioned and extends essentially parallel to the central axis A of the safety device 1. A second ramp 1.2.7 is formed to the distal end of the support body 1.2 that engages and deflects the resilient arm 1.1.2 in the radial inward direction when the needle shield 1.1 is displaced with respect to the support body 1.2 in the proximal direction, whereby the resilient arm 1.1.2 disengages the catching recess 1.2.3 to release the needle shield 1.1.

[0117] FIGS. 11A and 11B show two cross-sections of the needle shield 1.1 according to third embodiment of the invention. The sectional views shown in FIGS. 11A and 11B extend perpendicular to the central axis A of the safety device 1.

[0118] As can be seen in FIG. 11A, the retention and locking means M comprise two resilient arms 1.1.2 arranged opposite each other. The resilient arms 1.1.2 are in a mechanically unstressed state and latch to the catching recess 1.2.3. According to the third embodiment, the retention and locking means M comprises two interlocking elements 1.1.4 respectively arranged in the area between the two resilient arms 1.1.2.

[0119] The interlocking elements 1.1.4 are arranged opposite to each other and act as means to lock the two resilient arms 1.1.2 to each other when the resilient arms 1.1.2 are deflected in the radial inward direction after the resilient arms 1.1.2 engaged the second ramp 1.2.7, as illustrated in FIG. 11B. The inwardly deflected and stressed resilient arms 1.1.2 latch to the interjacent interlocking elements 1.1.4, so that the deflected resilient arms 1.1.2 are retained in an inwardly deflected position and locked together. The two interlocking elements 1.1.4 and the two resilient arms 1.1.2 form an essentially ring-shaped interlocked structure S.

[0120] FIG. 12 shows a sectional view of the injection device D according to the third embodiment of the invention with the needle shield 1.1 positioned in the retracted position PR.

[0121] The spring arm 1.4.1 engages the first ramp 1.2.6 and is deflected in the radial outward direction. The spring arm 1.4.1 is stressed and biases the needle shield 1.1 in the distal direction.

[0122] The resilient arm 1.1.2 engages the second ramp 1.1.2 arranged at the distal end of the support body 1.2. The second ramp 1.2.7 pushes the resilient arm 1.1.2 radial inwardly, so that the deflected resilient arm 1.1.2 is oriented with respect to the central axis A at an acute angle.

[0123] FIG. 13 shows the injection device D according to third embodiment of the invention after the dose of the medicament contained in the inner cavity 2.3.2 of the pre-filled syringe 2 has been administered to the patient. The support body 1.2 is substantially received within the outer body 1.3 and the stopper 2.4 is fully depressed in the inner cavity 2.3.2.

[0124] FIG. 14 shows the injection device D according to the third embodiment of the invention in the needle safe state. The needle shield 1.1 is locked to the second advanced position PA2 and surrounds the injection needle 2.1 to prevent accidental needle stick injuries.

[0125] The catch 1.2.2 formed to the distal end of the support body 1.2 latches to the second inward projection 1.2.5 connected to the needle shield 1.1 to permanently lock the needle shield 1.1 to the second advanced position PA2, so that a re-exposure of the injection needle 2.1 is prevented.

[0126] FIG. 15 shows a sectional view of an injection device D according to a forth embodiment of the invention. The forth embodiment represents one of many possible examples of injection devices D that are within the scope of the present invention and can be viewed as a particularly advantageous combination of the second and the third embodiment already described herein above.

[0127] In particular, the injection device D according to the forth embodiment is similar in outer appearance to the injection device D of the second embodiment and comprises the needle shield 1.1 of particular compact design. The retaining and locking means M are designed similar to the injection device D of the third embodiment and comprise two inwardly deflectable resilient arms 1.1.2 that may be locked to each other via interjacent locking elements 1.1.4 to form the interlocked structure S with essentially ring-shaped cross-section as illustrated in detail in FIGS. 11A and 11B.

[0128] The injection device D according to the third and forth embodiment of the invention is essentially used during an injection as described herein above. In particular, a possible sequence of actions include the removal of the needle cap 2.2 from the distal tip of the barrel 2.3, the arrangement of the injection device D at the injection site in manner, so that the annular flange 1.1.1 rests onto the skin of the patient, gripping the outer body 1.3 and pushing the outer body 1.3 towards the skin surface, whereby the needle shroud 1.1 first moves from the first advanced position PA1 to the retracted position PR before the outer body 1.3 is translated in the distal direction to inject the dose of the medicament. After the injection device D is taken away from the injection site, the spring means 1.4 relaxes and moves to the second advanced position PA2.

[0129] FIGS. 16A to 16D illustrate in detail the retention and locking means M according to the third and forth embodiment of the invention.

[0130] Before the injection, the needle shield 1.1 is initially retained in the first advanced position PA1 shown in FIG. 16A. The needle shield 1.1 is releasably retained in the first advanced position PA1 by the retaining arm 1.1.2 engaging the catching recess 1.2.3, wherein the retaining arm 1.1.2 is not mechanically stressed and extends essentially parallel to the central axis A. The needle shield 1.1 is released by a linear translation parallel to the central axis A in the proximal direction, whereby the second ramp 1.2.7 abuts and deflects the resilient arm 1.1.2 in the radial inward direction, as illustrated in FIG. 16B. The two deflected resilient arms 1.1.2 latch to the interlocking elements 1.1.4 to form the interlocked structure S as illustrated in FIG. 11B.

[0131] During the injection, the needle shield 1.1 moves further in the proximal direction until the needle shield 1.1 reaches the retracted position PR shown in FIG. 16C. The injection needle 2.1 protrudes the annular flange 1.1.1 resting on the skin of the patient and punctures the skin of the patient. After the dose of the medicament is disposed beneath the skin of the patient, the injection device is removed from the skin. The spring means 1.4 relaxes and pushes the needle shield 1.1 distally to surround the used injection needle 2.1 in the second advanced position PA2. The needle shield 1.1 is permanently locked to the advanced position PA2 to prevent needle stick injuries after use of the injection device D.

[0132] FIGS. 17A to 17D illustrate possible arrangements of a resilient arm 1.2.3 retaining the needle shield 1.1 relative to the support body 1.2 within the scope of the present invention.

[0133] FIG. 17B shows an arrangement of the resilient arm 1.1.2 formed to the needle shield 1.1. The resilient arm 1.1.2 is deflected in the radial inward direction to latch to the catching recess 1.2.3 formed into the distal end of the support body 1.1, so that the needle shield 1.1 is initially retained in the first advanced position PA1.

[0134] FIG. 17C shows an arrangement of the resilient arm 1.1.2 formed to the distal end of the support body 1.2. The resilient arm 1.1.2 is deflected in the radial inward direction to latch to the catching recess 1.2.3 formed into the needle shield 1.1, so that the needle shield 1.1 is initially retained in the first advanced position PA1.

[0135] FIG. 17D shows an arrangement of the resilient arm 1.1.2 formed to the distal end of the support body 1.2. The resilient arm 1.1.2 is deflected in the radial outward direction to latch to the catching recess 1.2.3 formed the needle shield 1.1, so that the needle shield 1.1 is initially retained in the first advanced position PA1.