Single use syringe

1. A plunger for a single use syringe having a co-operating barrel and a retractable needle engaged therewith, said plunger engageable with said retractable needle to facilitate retraction of said needle into said barrel, wherein said barrel has at least first and second projections and said plunger has a plurality of interconnected slots comprising a first slot, a second slot, a retraction slot and a fourth slot, said first slot connected to said second slot by a first deviation, said second slot connected to said retraction slot by a second deviation, said retraction slot connected to said fourth slot by a third deviation and said fourth slot connected to said first slot by a fourth deviation, which slots are slidably engageable by the first and second projections, whereby initially said first projection is locatable in said first slot and is capable of slidably moving from said first slot through said first deviation into said second slot and subsequently from said second slot through said second deviation into said retraction slot; and initially said second protection is locatable in said retraction slot and is capable of slidably moving from said retraction slot through said third deviation into said fourth slot and subsequently from said fourth slot through said fourth deviation into said first slot; wherein said slots are arranged so that slidable movement of said respective projections within said slots is restricted to thereby prevent re-use of the syringe.

2. The plunger of claim 1 , wherein the second slot includes a plurality of abutments engageable by said first projection to restrict withdrawal of said plunger.

3. The plunger of claim 1 , wherein the first slot includes an abutment engageable by said second projection to restrict depression of said plunger.

4. The plunger of claim 1 , wherein the retraction slot includes an abutment engageable by said first projection to restrict withdrawal of said plunger after retraction is complete.

5. The plunger of claim 1 , wherein said retraction slot includes an abutment engageable by said second projection to restrict depression of said plunger.

6. A single use retractable syringe comprising:

a barrel;

a retractable needle; and

a plunger engageable with said retractable needle to facilitate retraction of the needle into the barrel, wherein the barrel has at least first and second projections and the plunger has a plurality of interconnected slots comprising a first slot, a second slot, a retraction slot and a fourth slot, said first slot connected to said second slot by a first deviation, said second slot connected to said retraction slot by a second deviation, said retraction slot connected to said fourth slot by a third deviation and said fourth slot connected to said first slot by a fourth deviation, which slots are slidably engageable by the first and second projections, whereby initially said first projection is locatable in said first slot and is capable of slidably moving from said first slot through said first deviation into said second slot and subsequently from said second slot through said second deviation into said retraction slot; and initially said second projection is locatable in said retraction slot and is capable of slidably moving from said retraction slot through said third deviation into said fourth slot and subsequently from said fourth slot through said fourth deviation into said first slot; wherein said slots are arranged so that slidable movement of said respective projections within said slots is restricted to thereby prevent re-use of the syringe.

7. The syringe of claim 6 , wherein the second slot includes a plurality of abutments engageable by the first projection to restrict withdrawal of the plunger.

8. The syringe of claim 6 , wherein the first slot includes an abutment engageable by the second projection to restrict depression of the plunger.

9. The syringe of claim 6 , wherein the retraction slot includes an abutment engageable by the first projection to restrict withdrawal of the plunger after retraction is complete.

10. The syringe of claim 6 , wherein the retraction slot includes an abutment engageable by the second projection to restrict depression of the plunger.

11. A method for making a single use retractable syringe, the method comprising:

providing a barrel with a retractable needle adjacent one end of the barrel; and

slidably disposing at least a portion of a plunger in another end of the barrel, the plunger engageable with the retractable needle to facilitate retraction of the needle into the barrel, wherein the barrel has at least first and second projections and the plunger has a plurality of interconnected slots comprising a first slot, a second slot, a retraction slot and a fourth slot, said first slot connected to said second slot by a first deviation, said second slot connected to said retraction slot by a second deviation, said retraction slot connected to said fourth slot by a third deviation and said fourth slot connected to said first slot by a fourth deviation, which slots are slidably engageable by the first and second projections, whereby initially said first projection is locatable in said first slot and is capable of slidably moving from said first slot through said first deviation into said second slot and subsequently from said second slot through said second deviation into said retraction slot; and initially said second projection is locatable in said retraction slot and is capable of slidably moving from said retraction slot through said third deviation into said fourth slot and subsequently from said fourth slot through said fourth deviation into said first slot; wherein said slots have a movement restriction system so that slidable movement of the projections within the slots is restricted to a first path to prevent re-use of the syringe.

12. The method of claim 11 , wherein the second slot includes a plurality of abutments engageable by the first projection to restrict withdrawal of the plunger.

13. The method of claim 11 , wherein the first slot includes an abutment engageable by the second projection to restrict depression of the plunger.

14. The method of claim 11 , wherein the retraction slot includes an abutment engageable by the first projection to restrict withdrawal of the plunger after retraction is complete.

15. The method of claim 11 , wherein the retraction slot includes an abutment engageable by the second projection to restrict depression of the plunger.

16. The plunger of claim 2 further comprising at least one recess adjacent at least one of the abutments, the at least one recess is sized to provide a nesting position for at least one of the first and second projections.

17. The plunger of claim 2 further comprising at least one undercut region in at least one of the abutments.

18. The plunger as set forth in claim 2 wherein an outer edge on at least one of the abutments is substantially parallel to an opposing surface on the one of the barrel and plunger with the plurality of interconnected slots.

19. The plunger as set forth in claim 2 wherein a rear face on at least one of the abutments has an arc shape.

20. The plunger as set forth in claim 1 wherein the first and second projections extend in at least partially opposing directions.

21. The syringe of claim 7 further comprising at least one recess adjacent at least one of the abutments, the at least one recess is sized to provide a nesting position for at least one of the first and second projections.

22. The syringe of claim 7 further comprising at least one undercut region in at least one of the abutments.

23. The syringe as set forth in claim 7 wherein an outer edge on at least one of the abutments is substantially parallel to an opposing surface on the one of the barrel and plunger with the plurality of interconnected slots.

24. The syringe as set forth in claim 7 wherein a rear face on at least one of the abutments has an arc shape.

25. The syringe as set forth in claim 6 wherein the first and second projections extend in at least partially opposing directions.

26. The method of claim 12 further comprising forming at least one recess adjacent at least one of the abutments, the at least one recess is sized to provide a nesting position for at least one of the first and second projections.

27. The method of claim 12 further comprising forming at least one undercut region in at least one of the abutments.

28. The method as set forth in claim 12 further comprising forming an outer edge on at least one of the abutments which is substantially parallel to an opposing surface on the one of the barrel and plunger with the plurality of interconnected slots.

29. The method as set forth in claim 12 further comprising forming a rear face on at least one of the abutments which has an arc shape.

30. The method as set forth in claim 11 further comprising forming the first and second projections to extend in at least partially opposing directions.

31. The plunger of claim 1 , wherein the plunger rotates into a position engageable with said needle at the end of depression of the plunger to facilitate retraction of said needle.

32. The plunger of claim 31 , wherein the plunger following engagement of said retractable needle by said plunger, said plunger and needle engaged therewith rotate into an inoperable position to prevent re-use of the syringe.

33. The plunger of claim 32 , wherein said first projection and said second projection bear against respective abutments in respective slots of said plunger.

34. The syringe of claim 6 wherein the plunger rotates into a position engageable with said needle at the end of depression of the plunger to facilitate retraction of said needle.

35. The syringe of claim 34 wherein the plunger following engagement of said retractable needle by said plunger, said plunger and needle engaged therewith rotate into an inoperable position to prevent re-use of the syringe.

36. The syringe of claim 35 , wherein said first projection and said second projection bear against respective abutments in respective slots of said plunger.

37. The method of claim 11 wherein the plunger rotates into a position engageable with said needle at the end of depression of the plunger to facilitate retraction of said needle.

38. The method of claim 37 , wherein the plunger following engagement of said retractable needle by said plunger, said plunger and needle engaged therewith rotates into an inoperable position to prevent re-use of the syringe.

39. The method of claim 38 , wherein said first projection and said second projection bear against respective abutments in respective slots of said plunger.

40. The plunger of claim 1 , which is capable of rotating 180 degrees from when said first projection is initially located in said first slot and said second projection is initially located in said retraction slot to when said first projection is located within said retraction slot; and initially said second projection is located in said first slot.

41. The syringe of claim 6 , which is capable of rotating 180 degrees from when said first projection is initially located in said first slot and said second projection is initially located in said retraction slot to when said first projection is located within said retraction slot; and initially said second projection is located in, said first slot.