Patent ID: 8114051

Claim:
A retractable syringe comprising: a hollow barrel having a longitudinal axis extending in a longitudinal direction between a leading end and a trailing end of said barrel; a radially inwardly facing abutment surface which is fixed in relation to said barrel or forms part of said barrel; a needle hub mounted at said leading end of said barrel, said needle hub having a needle hub body and a first engagement formation integrally formed with said needle hub body, said first engagement formation having a leading end and a trailing end, said trailing end of said first engagement formation being joined to said needle hub body, wherein a radially outer portion of the first engagement formation projects radially beyond an exterior side wall of the needle hub prior to mounting of the needle hub within the barrel, and is engaged with said abutment surface after mounting of the needle hub within the barrel to radially inwardly bias the leading end of the first engagement formation; a needle tip connected to and in fluid communication with said needle hub body; and a plunger insertable within said barrel, said plunger having a stem and a head, said head including a second engagement formation; said plunger being displaceable through a longitudinal stroke in said longitudinal direction to an end of said stroke in which the inwardly biased leading end of said first engagement formation captively engages said second engagement formation, thereby engaging the plunger with the needle hub, said needle tip being retractable into said barrel, after engagement of said first engagement formation with said second engagement formation, upon application of a predetermined longitudinal force to said plunger in a retraction direction of the longitudinal stroke.