Abstract: A single use syringe in the form of a cylindrical barrel with a port end attached to a hypodermic needle. A plunger and piston in the barrel transfer liquid into or from the syringe through a port end. The plunger includes a locking structure formed at a predetermined position. An insert at a remote end of the barrel includes at least one cantilevered, longitudinally extending resilient arm with a radially acting, inwardly extending follower at a free end thereof that rides over the plunger. When the plunger moves to a locking position, the follower engages the plunger locking structure to block any further longitudinal motion of the plunger and piston preventing any subsequent use of the syringe.

Abstract: A single use syringe in the form of a cylindrical barrel with a first end attached to a hypodermic needle. A plunger and piston in the barrel draw liquid into the syringe through the hypodermic needle and eject the liquid through the hypodermic needle. The plunger includes a detent formed at an intermediate location. An insert at the second end of the barrel includes at least one cantilevered, longitudinally extending resilient arm with a follower at a free end thereof that rides over the plunger. When the plunger is pushed to a final position, the follower drops into the plunger detent to block any further longitudinal motion of the plunger and piston preventing any subsequent use.