Injection syringe

An injection syringe for an unstable freeze dried medicine, including a device for preparation of an injection comprising a multichambered cylindrical ampule;

• a tripartite case having a front case, a middle case, a rear case, and a needle holder;
• and a plunger, wherein:
• the multichambered cylindrical ampule includes at least two chambers of a front space and a rear space, the front space being sealed forwardly with a packing penetrable by a needle and sealed rearwardly with a movable front gasket, and the rear space being sealed forwardly with the front gasket and sealed rearwardly with a movable rear gasket, and the ampule further including a bypass route longitudinally arranged on an inner surface of the ampule such that the front gasket is located rearwardly of the bypass route before dissolution of an unstable freeze dried medicine wherein the front space for containing said medicine is separated from the rear space for containing a medicinal solvent or dispersing agent;
• the front case includes a tapered tip portion configured to fix a front edge of the ampule inside thereof, and a first fixer device provided externally at a rear end thereof, the middle case including longitudinally on an inner surface thereof a recess for receiving the bypass route and including a second fixer device provided internally at a front end thereof, and a flange provided internally at the rear end thereof to fixedly accommodate the ampule inside a housing formed of the front case and the middle case by tightening the first and second fixer devices;
• the middle case further includes a third fixer device provided externally at midportion thereof, and the rear case including a fourth fixer device provided internally at a front end thereof, and also a plunger retainer provided internally at a rear end thereof, the plunger being mounted in place by the plunger retainer and engaged at a front end of the plunger with a rear gasket;
• whereby, in a process of dissolving the unstable freeze dried medicine, pushing on the rear case toward the front of the ampule causes the front gasket and the rear gasket in unison to advance with aid of abutment at a shoulder provided at midportion of the plunger;
• then the front gasket enters into a bypass route's zone, the solvent or dispersing agent is released to flow into the front space through the bypass route such that an injection is prepared after the medicine has been dissolved or dispersed;
• then, tightening the third and fourth fixer devices to connect the middle case with the rear case avoids a reverse move of the shoulder with aid of the retainer, thus the prepared injection is maintained at a complete status, and pushing on the rear end of the plunger performs the injection through the needle holder;
• thus environmentally sensitive nature of the injection is overcome.

In a process for preparation of an injection applicable to unstable freeze dried medicine, with use of an injection syringe, said syringe, including a multichambered cylindrical ampule, a front case, a middle case, a rear case, a needle holder, and a plunger, said multichambered cylindrical ampule including two chambers of a front space and a rear space, the front space being sealed forwardly with a packing penetrable by a needle and sealed rearwardly with a movable rear gasket, and the ampule also including a bypass route longitudinally arranged on inner surface of the ampule such that the front gasket is located to take a position rearwardly apart from the bypass route before dissolution of an unstable freeze dried medicine, and wherein the ampule is set fixedly inside the front case and the middle case, and rear gasket is connected with the plunger;

• said process comprising the step of;
• containing the unstable freeze dried medicine into the front space and filling the rear space with a medical solvent or dispersing agent;
• erecting the injection syringe thus prepared in a front-up and rear-down status, pressing manually the injection syringe downwardly by the force acting on the plunger and at the moment that the front gasket enters into the bypass route zone, the solvent or dispersing agent filled in the rear space flows into the bypass route to dissolve or disperse the unstable freeze dried medicine in the front space wherein a flow rate is monitored and controlled manually by observation of a dissolving condition of said medicine, maintained in a laminar flow sate so as into the cause stirring and shaking during the dissolution;
• tighten by meshing thread parts or fixer means connecting the middle and rear cases after all solvent has been sent off the rear space, to avoid a reverse move of the gasket, thus the prepared injection is maintained ready to use.