Single-use syringe having misuse resistant features
 A syringe assembly includes a barrel having an inside surface describing a chamber for retaining fluid, an open proximal end and a distal barrel end having a passageway therethrough in fluid communication with the chamber. A plunger rod includes an elongate body portion, a proximal end and a distal end with a stopper at the distal end. The stopper is slidably positioned in fluid-tight engagement in the barrel. A locking element is positioned in the barrel between the plunger rod and the inside surface of the barrel. The locking element includes at least two proximally and outwardly facing non-parallel locking barbs, a distally and inwardly facing resisting edge and an inwardly facing driving edge. The driving edge is adaped to interact with the plunger rod to move the locking element along the barrel as the stopper is advanced distally along the barrel. The resisting edge and the locking barbs are adapted to prevent proximal motion of the plunger rod with respect to the barrel after initial distal motion of the plunger rod to expel fluid through the passageway wherein proximal motion of the plunger rod with respect to the barrel causes the resisting edge to engage the plunger rod causing the locking element to move in a proximal direction wherein the locking barbs engage the inside surface of the barrel to prevent further movement and allowing only distal movement of the plunger rod with respect to the barrel. 
Becton, Dickinson and Company
A A
A61M A61M
additional inventional
Anthony J.
Kosinski