Abstract: An exchangeable prefilled syringe (4) is arranged in the front part (2) of the device. In the rear part (1), a gear mechanism (3) is arranged, the drive member of which is a driving sleeve (10) provided with a manipulating head (11), and the driven member of which is a threaded rod (12) mounted non-rotationally but longitudinally displaceably in the driving sleeve. The threaded rod (12) is seated in the female thread (22) of a gear element (20) which can be advanced, by exerting pressure on the manipulating head (11) in the axial longitudinal direction from a rest position into an end position against the force of a spring (26).

Abstract: A driver sleeve (8) is pivoted in the casing (1) of the unit which is driven by a motor controlled by a control device and supplied by a battery. A threaded rod (11) forming the piston rod of an injection ampule (15) is placed into the driver sleeve (8) in a non-rotary but longitudinally shiftable fashion. A nut (21) provided with an external toothing (20) is rigidly held on the rear end of the injection ampule (15) in the casing (1). A connecting part (27) provided with a catheter (32) receives the outlet piece (30) of the injection ampule (15) and is screwed to the casing (1) so that the exchangeable injection ampule (15) is completely surrounded by the casing (1) and the connecting part (27) and the outlet piece (30), resting close to the connecting part (27), of the injection ampule (15) communicates with the catheter (32).