CARTRIDGE-NEEDLE UNIT HAVING RETRACTABLE NEEDLE

This invention relates to a novel cartridge-needle unit having a retractable needle for use with disposable or reusable holders to form safety syringes.The cartridge-needle unit comprises a cartridge (10) comprising a hollow body (14), a septum (18) at the distal end of the body (14), means (16) for retaining the septum (18), and a plunger (20), axially and reciprocally slidable through the interior of the body (14); a needle (22) capable of being retracted within the cartridge (10); a hub (24) comprising a sleeve (26) adapted to be snapped on the distal end of the cartridge (10); means (28,30,32) for retaining the needle (22) within the hub (24) during an injection; and means (28,30) for releasing the needle (22) from the hub (24) after the injection comprising an element (30) attached to the needle (22), and having a diameter greater than said needle, capable of passing through the septum (18).The retractable cartridge-needle unit exhibits improved reliability, reduces the tendency for body fluids and/or medication to remain in an unprotected area upon retraction of the needle and virtually eliminates the possibility that the needle can be released into the patient.