Patent ID: 7500967

Claim:
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.