Safety syringe and combination needle cannula and lock therefor.

摘要

A combination retractable needle cannula (32;68) and cannula lock (22;70) which is to be interfaced with a prefilled medication carpule (2;62) at the cylinder of a conventional hypodermic syringe (50). The cannula lock includes a clamp having a pair of oppositely disposed jaws (26;76) which are normally separated from one another so that the needle cannula can be releasably retained therebetween. In the pre-injection state, the jaws of the clamp are surrounded by and rotated towards one another by an expandable outer sleeve (60) so as to retain the cannula in an axially extended position between the jaws for administering an injection. In the post-injection state, and after the contents of the carpule have been expulsed via the cannula, the clamp is displaced by the carpule outwardly of the sleeve, whereby the jaws of the clamp are free to rotate away from one another to release the cannula. The cannula may then be retracted within and completely surrounded by the empty carpule so that the cannula can be safely discarded after use while avoiding an accidental needle stick and the spread of a contagious, and possibly life threatening, disease.