Abstract: A non-resuable syringe has inner and outer barrels including a needle connected by hub to the inner barrel and a plunger attached to the outer barrel and received within the inner barrel. A pair of circumferentially adjacent longitudinally extending tracks in the form of teeth are on the outer surface of the inner barrel and a traveler is fixed to the inner surface of the outer barrel, the teeth being such that the traveler may ride on each track in only one direction. The outer barrel may be rotated to move the traveler from an outgoing track for charging the syringe to an incoming track for discharging the syringe, but the teeth on the outgoing track have a greater height than the teeth on the incoming track so that the traveler cannot move back onto the outgoing track. The hub has a flange including an inclined needle facing surface. A protective cap having a skirt at the open end may be disposed on the hub with the skirt removeably positioned on the flange.

Abstract: A non-reusable syringe has inner and outer barrels including a needle connected by a hub to the inner barrel and a plunger attached to the outer barrel and received within the inner barrel. A pair of circumferentially adjacent longitudinally extending tracks in the form of teeth are on the outer surface of the inner barrel and a traveler is fixed to the inner surface of the outer barrel, the teeth being such that the traveler may ride on each track in only one direction. One of the tracks is an outgoing or charging track which permits the outer barrel and the plunger to be drawn away from the needle end of the inner barrel to charge the inner barrel with injectable fluid. The other track is an incoming or discharge track permitting the traveler to ride in the direction toward the needle to permit the outer barrel and plunger to discharge fluid through the needle.