Single use syringe and plunger rod locking device therefor.

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 present the locking element from moving proximally within the barrel, but allow its distal movement therein with the plunge rod assembly. A spring member may be provided for urging the barbs towards the inside surface of the barrel. The barbs are preferably positioned on the edge portions of opposing legs that form part of the locking element.