Abstract: The present invention is a modified single use hand-operated injector device consisting of a plunger, a base, a snap means for resisting plunger movement and an injection means for injecting parenteral medication through a skin surface of a patient. The improvement comprises a check valve seated in a cannula and a widened receptacle area within a high pressure barrel through which the cannula passes. When the check-valve plug expels upon increase in pressure, into the widened receptacle area the parenteral medication efficiently flows around the plug and into the subcutaneous tissue of the patient.

Abstract: The present invention is a single use injector device for injecting parenteral medications which operates by hand force. The injector device has a plunger section and a base. As hand force is applied to a moving portion of the plunger section, break tabs or a snap ring resist its motion toward the patient's skin surface. The break tabs or snap ring release abruptly as the hand force reaches a snap point. The motion of the moving portion then drives the medication through the skin surface and into the body of the patient. If the medication is in liquid form, the actual injection may be carried out through a hollow needle attached to the plunger section. Alternatively, the suddenly increased pressure of the medication at the snap point may be used to form a liquid jet for needleless injection. Part or all of the medication may be contained in a glass needle which dissolves in the body after injection. The injector device requires little training to use, reduces perceived pain, and improves injection safety.