Insertable element for preventing reuse of plastic syringes

A locking device, capable of being retrofitted by insertion into a plastic syringe, wherein the syringe is of the type having a cylindrical inner wall elongated in the direction of a longitudinal axis thereof and made of a plastic material;

• a closed, distal end, and an open, proximal end for movement of a plunger thereon, the plunger having a plunger stem which extends in the direction of and is movable along the longitudinal axis of the syringe, the plunger stem being made of plastic material and having at least one longitudinal rib formed therewith, said locking device comprising:
• a clip-type body portion formed of a compact size and shape to allow its insertion through the open end of the syringe between the plunger stem and the inner wall of the syringe, and having a U-shaped channel for clipping onto the at least one longitudinal rib of the plunger stem,
• said clip-type body portion of said locking device being formed with a first set of barbed points spaced apart in a transverse direction perpendicular to the longitudinal axis of the syringe and angled toward the plunger stem facing in the direction toward the proximal end of the syringe for engaging into the plastic material of the plunger stem when the plunger stem is depressed toward the distal end of the syringe after a first retraction movement toward the proximal end of the syringe, and a second set of barbed points spaced apart in the transverse direction and angled toward the inner wall of the syringe facing in the direction toward the proximal end of the syringe for engaging into the plastic material of the syringe inner wall in order to lock the plunger stem from a second retraction movement, thereby preventing reuse of the syringe.