abstract |
Devices and methods are disclosed for drug delivery systems which involve taking up and controlling a predetermined volume of liquid drug from a liquid drug container (933) into a volume measurement chamber (950) in a first step, and then expelling the predetermined volume to the administration element such as an injection needle in a second step. The volume measurement chamber (950) may operate as a piston-and-cylinder construction in which a threaded engagement between a control knob (966) and a threaded piston rod (934) enables the piston to be progressively withdrawn to a predetermined extent. This determines the volume drug. Pushing the same control knob (966) uncouples the threads and reduces the piston (952) to be pushed forward by a spring (960) to pump the predetermined volume of drug out through the administration element (e.g. needle). |