Single use syringe and plunger rod locking device therefor

摘要

A single use syringe assembly is provided as well as a locking element for such an assembly. The single use syringe assembly includes a barrel, a plunger rod assembly and a locking element positioned within the barrel. The locking element includes one or more barbs for engaging the inside surface of the barrel. The barbs prevent the locking element from moving proximally within the barrel, but allow its distal movement therein with the plunger rod assembly. A spring member may be provided for urging the barbs towards the inside surface of the barrel. Structure provided for holding the proximal end and the distal end of the plunger rod assembly together during normal use of the syringe is breakable upon application of an additional force applied to the proximal end of the plunger rod.