Retractable syringe

A hypodermic syringe having;

• a barrel with an open end, a base end and an internal bore and a locking means at the base end;
• a needle assembly including a needle base member located inside the bore and releasably engaged with the base end and a needle which protrudes through the base, end of the barrel;
• a plunger slidable within the bore, a piston releasably engaged with the plunger and a chamber having air evacuated therefrom the chamber being sealed at one end by the piston;
• wherein the piston includes means for engaging the needle base member such that in use when the plunger is depressed and the piston approaches the base end of the barrel, the piston engages the needle base member, the needle base member is released from the base end, the plunger releases the piston and simultaneously engaged by the locking means at the base end of the barrel;
• such that the piston, needle base member and needle are forced into the chamber by atmospheric pressure and the plunger remains engaged with the barrel so that it may not be removed from the bore.

A hypodermic syringe having:

• a barrel with an open end, a base end and an internal bore;
• a needle assembly including a needle base member releasably engaged with the base end and a needle which protrudes from the base end of the barrel;
• a plunger slidable within the bore, the plunger having a piston head releasabley engaged therewith and a chamber having air evacuated therefrom, the chamber being sealed at one end by the piston;
• wherein the piston includes means for engaging the needle base member such that in use when the plunger is depressed and the piston approaches the base end of the barrel, the piston engages the needle base member and, the needle base member is released from engagement with the base end of said barrel and the piston is thereafter released from, the engagement with the plunger whereby the piston, needle base member, and needle are forced into the chamber by atmospheric pressure.