Disposable injector with dual-piston dual-chamber system

In combination with a disposable injector including a housing (10), a cylinder-piston unit (100)—at least intermittently fillable—arranged thereon, an upstream detachable container adapter (200) housing a second cylinder-piston unit (250), the second cylinder-piston unit (250) at least intermittently fillable, the cylinder-piston unit (100) including a piston (111) and an injector-side cylinder (101) having an interior space (110), the improvement which comprises:

• the piston (111) of the cylinder-piston unit (100) is movably arranged in a suction- and pressure-controlled manner in the cylinder (101), the cylinder (101) sealed at the back thereof in the delivery state;
• the container adapter (200) is attached detachably to the disposable injector via a coupling element (230), in which the container adapter (200) sits displaceable longitudinally;
• the container adapter (200) includes an adapter region (201) and a container region (221), an intermediate floor (211) separates both of the regions (201, 221), the intermediate floor (211) having throughhole (212) passing therethrough;
• between the intermediate floor (211) and the cylinder (101) a needle holder (240) operatively sits, the cylinder (101) having a front abutting face (103) operatively positioned closely adjacent needle holder (240), the needle holder (240) having an injection needle (242) operatively affixed thereto in controllable intermittent fluid communication with the interior space (110) of the cylinder (101);
• the second cylinder-piston unit (250) is operatively arranged in the container adapter (200) at the back thereof, an elastic stopper (257) is in tight sealed relationship with the front of the cylinder-piston unit (250)—in a delivery state—and a piston (261) is secured detachably and against running in at the back of the cylinder-piston (250);
• the injection needle (242) has a tip (243) that terminates operatively sealed in the stopper (257) prior to activation;
• the second cylinder-piston unit (250) includes a second cylinder (251) having an interior space (252), the container adapter (200) is mounted displaceably against the needle holder (240) in the coupling element (230), the tip (243) of the injection needle (242) is operatively displaceable to pass through stopper (257) and enter interior space (252) of the second cylinder (251), whereby prior to use of the injector for administering to a patient the injection needle (242) upon displacement provides a temporary fluid communication connection between the interior space (110) of the injector-side cylinder (101) and the interior space (252) of the second cylinder (251).