Abstract: A hypodermic jet injector employing self-contained, patient fillable, thin-walled disposable ampules. Each ampule includes an elongate plastic body with an injection orifice at a first end, an internal propellant at a closed second end, and a double piston slidably and sealingly mounted within the body entirely between the orifice and the internal propellant, and also includes an auxiliary access opening in the ampule side wall. An ampule chamber with a corresponding access opening in its_side wall is provided to receive and support the thin-walled ampule. The main body of the ampule is molded with draft angles, and the double piston construction includes a soft rubber plunger and a relatively hard plunger to the front and rear, respectively, of the auxiliary access opening in the ampule, with the two plungers interconnected by a connecting rod spanning the central section of the ampule.

Abstract: A hypodermic jet injector employing self-contained, patient fillable, thin-walled disposable ampules. Each ampule includes an elongate plastic body with an injection orifice at a first end, an internal propellant at a closed second end, and a double piston slidably and sealingly mounted within the body entirely between the orifice and the internal propellant, and also includes an auxiliary access opening in the ampule side wall. An ampule chamber with a corresponding access opening in its side wall is provided to receive and support the thin-walled ampule. The main body of the ampule is molded with draft angles, and the double piston construction includes a soft rubber plunger and a relatively hard plunger to the front and rear, respectively, of the auxiliary access opening in the ampule, with the two plungers interconnected by a connecting rod spanning the central section of the ampule.