Abstract: An instrument having a dosing unit connected to a handle or housing of instrument. The dosing unit may include a reusable actuator with a drive unit and a single-use cartridge. The Cartridge may have a cylinder and a piston, and may be filled by a user prior to the intervention or may be prefilled by the manufacturer. The dosing unit is brought into an open position offset from housing by, for example, operating a latch slider and pulling the dosing unit in a proximal direction. After insertion of the cartridge, the dosing unit may be moved toward housing and the latched slider will lock the dosing unit into a closed position.