AUTOINJECTOR

• US 20100130930A1
• Filed: 03/04/2008
• Published: 05/27/2010
• Est. Priority Date: 03/07/2007
• Status: Active Grant

• Current Assignee: Shl Medical AG
• Original Assignee: The Medical House PLC (Recipharm AB)
• Inventors: Cleathero, Charles Ian, Stamp, Kevin
• Granted Patent: US 8,187,226 B2
• Time in Patent Office: Days
• US Class Current: 604/135
• CPC Class Codes: A61M 2005/206 With automatic needle insertion
• CPC Class Codes: A61M 5/2033 Spring-loaded one-shot injectors with or without automatic needle insertion multishot dosing syringes A61M5/31525, needle insertion only A61M5/3287
• CPC Class Codes: A61M 5/326 Fully automatic sleeve extension, i.e. in which triggering of the sleeve does not require a deliberate action by the user

Abstract

An autoinjector comprising an outer housing in which is mounted a syringe, the autoinjector further comprising an inner housing intermediate the outer housing and the syringe and an energy source in communication with said inner housing, wherein the inner housing is moveable by the energy source between three positions, namely a first position in. which the inner housing is in communication with the barrel such that, in use, the plunger and barrel are moveable axially so as to move at least part of said needle out of the outer housing; a second position in which the inner housing is in communication with the plunger but not the barrel such that, in use, said plunger is moveable axially into said barrel so as to expel medicament through the needle; and a third position in which the inner housing is in communication with neither the plunger nor the barrel such that, in use, the plunger and barrel are able to retract in order to retract the needle into the outer housing, characterised in that the plunger includes biasing means for axially biasing the barrel, before activation of the energy source, to a position forward of the part of the inner housing which acts on the barrel in said first position.

Claims

1. An autoinjector comprising an outer housing in which is mounted a syringe comprising

a barrel for holding a volume of medicament,

a needle at one end of the barrel and

a plunger axially-moveable in the barrel,

the autoinjector further comprising an inner housing intermediate the outer housing and the syringe and an energy source in communication with said inner housing,

wherein the inner housing is moveable by the energy source between three positions, namely

a first position in which the inner housing is in communication with the barrel such that, in use, the plunger and barrel are moveable axially so as to move at least part of said needle out of the outer housing;

a second position in which the inner housing is in communication with the plunger but not the barrel such that, in use, said plunger is moveable axially into said barrel so as to expel medicament through the needle; and

a third position in which the inner housing is in communication with neither the plunger nor the barrel such that, in use, the plunger and barrel are able to retract in order to retract the needle into the outer housing,

characterised in that the autoinjector includes biasing means for axially biasing the barrel, before activation of the energy source, to a position forward of the part of the inner housing which acts on the barrel in said first position.

2. The autoinjector of claim 1 wherein said biasing means acts on said plunger.

3. The autoinjector of claim 1 wherein said biasing means comprises a compression spring held between the outer housing and the plunger.

4. The autoinjector of claim 3 wherein said compression spring is integrally-formed with said plunger.

5. The autoinjector of claim 3 wherein said compression spring is integrally-formed with said outer housing.

6. The autoinjector of claim 3 wherein said compression spring is separable from said plunger and/or said outer housing.

7. The autoinjector of claim 3 wherein said compression spring is provided with a rear flange for abutment with a part of said outer housing.

8. The autoinjector of claim 1 wherein said biasing means is associated with the front end of said inner housing.

9. The autoinjector of claim 8 wherein said biasing means is located in the axial path of said barrel.

10. The autoinjector of claim 9 wherein said biasing means is not strong enough to resist a forward axial force provided by said energy source in communication with said inner housing.

11. The autoinjector of any claim 8 wherein said biasing means comprises a radially-flexible leg integrally-formed with said inner housing.

12. The autoinjector of claim 11 wherein said inner housing is provided with a plurality of said radially-flexible legs.

13. The autoinjector of claim 1 wherein said biasing means comprises a chamber containing a piston in a shear thickening fluid which, upon activation of said energy source, is capable of transmitting forward axial force from said energy source to the plunger, and a compression spring held between the outer housing and said piston.

14. The autoinjector of any of claim 1 further comprising means associated with a rear flange of said plunger providing a plurality of axial positions at which it is possible for said inner housing to engage said plunger in said second position.

15. The autoinjector of claim 14 wherein said means comprises a chamber containing a piston in a shear thickening fluid which, upon activation of said energy source, is capable of transmitting forward axial force from said energy source to the plunger, and a compression spring held between the outer housing and said piston.

16. The autoinjector of claim 14 wherein said means comprises a ratchet cap intermediate said inner housing and said plunger.

21. The autoinjector of claim 1 further comprising syringe support means for supporting the barrel at an axial location at or forward of a forwardmost position of the plunger and having a reaction surface for the syringe, whereby in use said reaction surface provides an axial compressive force on said barrel when a forward axial force is applied to the plunger.

22. The autoinjector of claim 1 wherein said autoinjector is a single-use autoinjector.

23. The autoinjector of claim 1 wherein said energy source is capable of moving said plunger axially in the barrel to deliver an injection in less than 30 seconds.

24. The autoinjector of claim 1 wherein said inner housing comprises one or more radially-flexible tags.

25. The autoinjector of claim 24 wherein one or more of said tags is located at the end of a resiliently flexible leg.

26. The autoinjector of claim 24 wherein one or more of said tags are situated at the rear end of the inner housing and are moveable radially into and out of communication with the plunger.

27. The autoinjector as claimed in claim 24 wherein one or more of said tags are situated at the forward end of the inner housing and are moveable radially into and out of communication with the barrel.

28. The autoinjector as claimed in claim 24 wherein said tags are stored in their relaxed, radially-outward, condition, before initiating an injection.

29. The autoinjector as claimed in claim 27 wherein said rear tags are radially offset from said forward tags, preferably by 45°

.

30. The autoinjector of claim 1 wherein the syringe is axially moveable in said housing and is biased so that the needle is normally wholly inside said housing, wherein before injection the syringe is movable axially so as to move at least a part of said needle out of the housing and wherein after injection, the syringe is able to retract in order to retract said part of said needle into the housing.

31. The autoinjector of claim 21 wherein, in use, said reaction surface provides an axial compressive force to the front shoulder or the front cone of the syringe barrel.

32. The autoinjector of claim 21 wherein said syringe support means includes one or more inwardly-directed protrusions forming said reaction surface.

33. The autoinjector of claim 32 wherein said inwardly-directed protrusions are on the end of one or more radially-flexible fingers.

34. The autoinjector of claim 32 wherein, when the device is fully assembled ready for use, said inwardly-directed protrusions are axially located between a needle cover and the front shoulder of the syringe barrel.

35. The autoinjector of claim 21 wherein the finger flange of the syringe barrel does not contact the syringe support means during delivery of the medicament.

36. The autoinjector of claim 32, wherein said radially-flexible fingers can flex sufficiently outwardly to allow a needle cover or the like of larger diameter than the internal diameter between said radially-flexible fingers to pass thereby during assembly of a syringe into said autoinjector.

17. An autoinjector comprising an outer housing in which is mounted a syringe comprising

a barrel for holding a volume of medicament,

a needle at one end of the barrel and

a plunger axially-moveable in the barrel,

the autoinjector further comprising an inner housing intermediate the outer housing and the syringe and an energy source in communication with said inner housing,

wherein the inner housing is moveable by the energy source between three positions, namely

a first position in which the inner housing is in communication with the barrel such that, in use, the plunger and barrel are moveable axially so as to move at least part of said needle out of the outer housing;

a second position in which the inner housing is in communication with the plunger but not the barrel such that, in use, said plunger is moveable axially into said barrel so as to expel medicament through the needle; and

a third position in which the inner housing is in communication with neither the plunger nor the barrel such that, in use, the plunger and barrel are able to retract in order to retract the needle into the outer housing, characterised in that the autoinjector further comprises means associated with a rear flange of said plunger providing a plurality of axial positions at which it is possible for said inner housing to engage said plunger in said second position.

18. The autoinjector of claim 17 wherein said means comprises a chamber containing a piston in a shear thickening fluid which, upon activation of said energy source, is capable of transmitting forward axial force from said energy source to the plunger, and a compression spring held between the outer housing and said piston.

19. The autoinjector of claim 17 wherein said means comprises a ratchet cap intermediate said inner housing and said plunger.

20. The autoinjector of claim 17 further including biasing means for axially biasing the barrel, before activation of the energy source, to a position forward of the part of the inner housing which acts on the barrel in said first position.

37. (canceled)