Medical injection device having a telescopically movable shield

Abstract

The invention relates to a pre-filled injection device for apportioning a plurality of set doses of a liquid drug comprising. The housing of the injection device supports a non-replaceable cartridge containing the liquid drug. The cartridge is e.g. secured in a cartridge-holder being a part of the housing. A needle assembly comprising a needle cannula secured in a hub is slidable mounted to slide into contact with the cartridge. The tip of the needle cannula is covered by a telescopically movable shield movable from an extended position to a retracted position. The telescopically movable shield supports a cleaning chamber containing a cleaning solvent for cleaning at least the distal tip of the needle cannula between subsequent injections. The distal end of the housing supports a removable protective cap and the telescopically movable shield is guided relatively to the housing and coupled to the protective cap to follow movement of the protective cap.

Claims

1. A pre-filled injection device for apportioning set doses of a liquid drug comprising: A pen-shaped housing extending in a longitudinal direction and having a needle supporting distal end, A removable protective cap mountable on the housing and covering at least a part of the needle supporting distal end between injections, and which removable protective cap is rotatable relatively to the housing when mounted there upon, A non-replaceable cartridge permanently embedded in the housing of the pre-filled injection device and having an interior containing the liquid drug, A needle assembly comprising a needle cannula secured in a hub which needle cannula has a distal end with a distal tip and a proximal end and wherein the proximal end of the needle cannula is inserted into the cartridge, A telescopically movable shield movable from an extended position covering at least the distal tip of the needle cannula to a retracted position and which telescopically movable shield carries a cleaning chamber containing an amount of the same liquid drug as contained in the cartridge for cleaning at least the distal tip of the needle cannula between subsequent injections, and which telescopically movable shield is rotatably mounted relatively to the housing, wherein the removable protective cap when mounted engages the telescopically movable shield such that rotation of the protective cap relatively to the housing is transformed to a rotation of the telescopically movable shield.

2. A pre-filled injection device according to claim 1, wherein the protective cap internally is provided with the structure for engaging the shield.

3. A pre-filled injection device according to claim 2, wherein the structure provided internally in the protective cap is a gripping structure for engaging a longitudinal track provided in the shield.

4. A pre-filled injection device according to claim 3, wherein the gripping structure is formed with shoulders for transferring an axial force on to the telescopically movable shield.

5. A pre-filled injection device according to claim 1, wherein the telescopically movable shield is provided with a guiding track.

6. A pre-filled injection device according to claim 5, wherein the injection device is provided with a protrusion engaging the guiding track.

7. A pre-filled injection device according to claim 6, wherein the protrusion is provided on the housing or on a part of the housing.

8. A pre-filled injection device according to claim 5, wherein the guiding track has a helical track part.

9. A pre-filled injection device according to claim 8, wherein the helical track part connects a first axial track part and a second axial track part.

10. A pre-filled injection device according to claim 1, wherein the telescopically movable shield is urged distally by resilient spring structure.

11. A pre-filled injection device according to claim 1, wherein the needle assembly is slidable mounted relatively to the housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1 show a perspective view of the injection device in the initial state.

(3) FIG. 2 show a perspective view while rotating the protective cap.

(4) FIG. 3 show a perspective view while continuing rotation of the protective cap.

(5) FIG. 4 show a perspective view of the injection device with the protective cap removed.

(6) FIG. 5 show a cross sectional view of the injection device according to the invention.

(7) FIGS. 6 to 10 show perspective views of the telescopically movable shield.

(8) FIG. 11 show a cross sectional view of the injection device in the initial position as disclosed in FIG. 1 and in FIG. 6.

(9) FIG. 12 show a cross sectional view of the injection device with the protective cap moved proximally as disclosed in FIG. 2 and FIG. 7.

(10) FIG. 13 show a cross sectional view of the injection device during filling of the cleaning chamber.

(11) FIG. 14 show a cross sectional view of the injection device with the protective cap rotated to the position of FIG. 3 and FIG. 8.

(12) FIG. 15 show a cross sectional view of the injection device in a ready-to-use situation with the protective cap mounted.

(13) FIG. 16 show a cross sectional view of the injection device in a ready-to-use situation with the protective cap removed.

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

DETAILED DESCRIPTION OF EMBODIMENT

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

(16) In that context it may be convenient to define that the term distal end in the appended figures is meant to refer to the end of the injection device which usually carries the injection needle whereas the term proximal end is meant to refer to the opposite end pointing away from the injection needle and usually carrying the dose dial button.

(17) Further, as indicated in FIG. 12, the axis X is the longitudinal centre axis of the injection device and thus defines the axial direction of the injection device herein disclosed as being pen-shaped.

(18) Distal and proximal is further indicated in FIG. 11 which also shows the axial axis X of the injection device 1.

(19) FIGS. 1 to 4 discloses the injection device 1 according to a first embodiment.

(20) Proximally the injection device 1 is provided with a dose setting button 5 that the user can rotate in order to set the dose. The dose setting button 5 is axially secured to the housing 2 such that the dose setting button 5 does not translate axially when rotated. The dose set by this rotation is shown by indicia on a scale drum appearing in a dose window 3 in the housing 2.

(21) The distal end of the injection device 1 is in FIGS. 1 to 3 covered by a removable protective cap 10 which can be manipulated by the user as will be explained.

(22) FIG. 4 depicts the injection device 1 with the protective cap 10 removed. Distally a telescopically movable shield 20 covers the needle cannula 32 (shown in FIG. 5). Further in FIG. 4, the protective cap 10, when mounted, covers a window 4 in the housing 2, through which window 4, the user is able to visually inspect the drug contained in the cartridge 40 embedded in injection device 1.

(23) The telescopically movable shield 20 is able to move in a proximal direction and is urged distally by a non-shown resilient element such as a spring. The distal end of the telescopically movable shield 20 has an opening 21 through which the needle cannula 32 can protrude and is further provided with longitudinal tracks 22 which are engaged by gripping means 11 provided internally in the protective cap 10 as best seen in FIG. 11.

(24) The injection device 1 is further disclosed in FIG. 5. The shield 20 covers the needle assembly 30 which comprises a hub 31 and a needle cannula 32 connected to the hub 31. The hub 31 is further provided with an outwardly pointing protrusion 35 and the hub 31 is able to slide axially in relation to the housing 2 but is rotational secured to the housing 2 such that the hub 31 and thus the needle assembly 30 can only slide axially without rotation.

(25) The telescopically movable shield 20 is as disclosed in FIGS. 6 to 10 besides the opening 21 and the longitudinal tracks 22 further provided with a guiding track 23, 24, 25 which guides the shield 20 in relation to the outwardly pointing protrusion 35. This guiding track 23, 24, 25 has a helical track part 23 helically connecting a first axial track part 24 with a second axial track part 25.

(26) In the above embodiment the protrusion 35 is positioned on the needle hub 31 as depicted in FIG. 5 but the protrusion 35 could in a different embodiment be disposed anywhere on the outer surface of the part of the housing 2 supporting the shield 20. The guiding track 23, 24, 25 could also be provided in a different position than disclosed in the figures as long as the protrusion 35 slides in the guiding track 23, 24, 25.

(27) The injection device 1 is disclosed in further details in the FIGS. 11 to 16 and comprises; The housing 2 which proximally holds the dose setting button 5. Further, the housing 2 secures the cartridge 40 which hold the liquid drug to be injected. A cartridge-holder 6 can be present as a part of the housing 2. The cartridge-holder 6 can either be moulded as an integral part of the housing 2 or it can be a separate part permanently connected to the housing 2. The cartridge 40 is distally provided with a septum 41 to be pierced by the needle cannula 32 as will be explained. Proximally the cartridge 40 is provided with the usual plunger which is moved forward by a drive mechanism including a piston rod. The protective cap 10 provided with internal gripping means 11 for interacting with the telescopically movable shield 20. The gripping means 11 is formed to rotational interact with the telescopically movable shield 20 via the longitudinal tracks 22 provided in the telescopically movable shield 20 and is further shaped with shoulders 12 to engage with the telescopically movable shield 20 in the longitudinal direction. Further, the proximal cap 10 is slidable in an axial direction in relation to the housing 2. As seen in e.g. FIG. 11, the shoulders 12 abut the proximal end of the longitudinal tracks 22. The telescopically movable shield 20 which distally carries, as e.g. seen in FIGS. 11 to 16, a cleaning chamber 26 which is encompassed between a distal septum 27 and a proximal piston 28. The needle assembly 30 which comprises the hub 31 with the needle cannula 32 attached thereto. The needle cannula 32 has a distal part 33 protruding in a distal direction from the hub 31 and a proximal part 34 protruding in the proximal direction from the hub 31. The distal part has a sharp tip 36 (FIG. 14) for penetrating the skin of the user during injection.

(28) When the injection device 1 is delivered to the user, the protective cap 10 is not fully moved to its proximal position as disclosed in FIG. 1 and FIG. 11. In this initial position the outwardly protrusion 35 provided on the hub (31) or on a part of housing 2 (e.g. the on the cartridge-holder 6) is held in the proximal end of the first axial track 24 as disclosed in FIG. 6.

(29) In order to start using the injection device 1, the user applies a pressure P to the protective cap 10 thus pushing the protective cap 10 in the proximal direction a distance Y as indicated in FIG. 1 and FIG. 11. This axial movement is transferred to a proximal movement of the telescopically movable shield 20 via the shoulders 12 of the gripping means 11 such that the telescopically movable shield 20 moves proximally together with the protective cap 10.

(30) As the telescopically movable shield 20 move proximally the outwardly protrusion 35 move to the distal end of the first axial track 24 as disclosed in FIG. 7. The axial movement of the shield 20 also moves the needle assembly 30 in the proximal direction. As a result the needle assembly 30 and thus the needle cannula 32 are moved proximally whereby the proximal part 34 of the needle cannula 32 penetrates through the distal septum 41 of the cartridge 40 as disclosed in FIG. 12.

(31) In this situation disclosed in FIG. 2 and FIG. 12 the interior of the cartridge 40 is in liquid communication with the cleaning chamber 26 which can then be filled with liquid drug from the cartridge 40.

(32) The filling can be done either manually by the user expelling liquid drug directly into the cleaning chamber 26 or it can be done automatically by providing the interior of the cartridge 40 with an overpressure such that liquid drug will start to flow once the distal end 34 of the needle cannula 32 penetrates through the septum 41.

(33) The overpressure can thus either be existing inside the cartridge 40 when the injection device 1 is delivered to user or it can be introduced by the user e.g. by moving the cartridge 40 and the drive mechanism relatively to the each other in an axial direction when initiating the injection device 1.

(34) As the cleaning chamber 26 is filed, the piston 28 is moved in the proximal direction until it encounters a stop 29 as disclosed in FIG. 13. Since the overpressure inside the cartridge 40 can occasionally be larger than the distance the piston 28 is allowed to move proximally due to the stop 29 it is important to vent the system to equalize the pressure before making the injection as will be explained.

(35) FIG. 13 discloses the situation in which the cleaning chamber 26 has been filled as the protective cap 10 has been moved proximally the distance Y. The piston 28 now abuts the stop 29 and the cleaning chamber 26 is thus filled with drug from the cartridge 40. The liquid system comprising the interior of the cartridge 40, the lumen of the needle cannula 32 and the cleaning chamber 28 can is this situation have an overpressure which can potentially result in overdosing why it is necessary to vent the liquid system.

(36) In the situation disclosed in FIG. 13, the outwardly pointing protrusion 35 is located in the distal end of the axial track 24 as disclosed in FIG. 7.

(37) The user then starts to rotate the protective cap 10 as indicated by the arrow R in FIG. 2. This courses the telescopically movable shield 20 also to rotate and to move in the proximal direction due to engagement between the helical track 28 and the outwardly pointing protrusion 35.

(38) As the telescopically movable shield 20 is rotated it move helically in the proximal direction and the sharp tip 36 of the needle cannula 32 penetrates through the distal septum 27 as depicted in FIG. 14. In this position, the overpressure will be equalized by a small quantum of drug automatically being ejected into the interior of the protective cap 10.

(39) In order to collect the ejected amount of liquid drug, the protective cap 10 can internally be provided with a small absorbent sponge or the like.

(40) In FIG. 3, the user keeps rotating the protective cap 10 and thus the telescopically movable shield 20 until the outwardly protrusion 35 enters the second axial track 25 as depicted in FIG. 8. The situation disclosed in FIG. 8 where the outwardly pointing protrusion 35 abuts the sidewall of the second axial track 25 equals the situation in FIG. 14 wherein the distal tip 36 of the needle cannula 32 protrudes beyond the distal septum 27 thus venting the liquid system. However, in this situation, the non-shown spring urges the telescopically movable shield 20 in the distal direction as indicated by the arrow A in FIG. 9 such that the distal tip 36 of the needle cannula 32 is positioned inside the cleaning chamber 26 as disclosed in FIG. 15. In this situation the injection device 1 is ready for use.

(41) Since the overpressure has now been equalized, the dose injected is identical to the dose set by the user using the dose setting button 5.

(42) In the ready-to-use situation, the user only needs to set the required dose and remove the protective cap 20 as disclosed in FIG. 16. The telescopically movable shield 20 is now slidable in the length of the second axial track 25 and the telescopically movable shield 20 can slide between the two positions of the outwardly pointing protrusion 35 disclosed in FIG. 9 and FIG. 10 as indicted by the arrow B in FIG. 10.

(43) When the shield 20 is positioned in the position disclosed in FIG. 10, the distal tip 36 of the needle cannula 32 has penetrated through the skin of the user and the set dose is released. Usually the injection device 1 would be an automatic torsion spring operated injection device wherein the torque stored in the torsion spring would be released by the proximal movement of the shield 20.

(44) Some preferred embodiments have been shown in the foregoing, but it should be stressed that the invention is not limited to these, but may be embodied in other ways within the subject matter defined in the following claims.