IMPROVEMENTS IN AND RELATING TO DRIVE MECHANISMS SUITABLE FOR USE IN DRUG DELIVERY DEVICES

摘要

Provided is a drive mechanism for use in a drug delivery device is provided comprising: a housing having a proximal and a distal end; a drive member located within the housing such that the drive member is movable longitudinally and is non-rotatable with respect to the housing; a piston rod that is non-rotatable with respect to the housing and having at least one set of teeth, and is adapted to operate through the housing and transfer a force in the longitudinal direction to the distal end of the drug delivery device; a rotating means releasably engaged with the piston rod and engaged to the drive member and engaged to the housing wherein the rotating means is selected from the group of (i) to (ii), (i) a gear the axle of which is engaged with the set of teeth of the piston rod, (ii) a pulley comprising a belt and a wheel the axle of which is engaged with the set of teeth of the piston rod; characterized in that, a) when the drive member moves proximally with respect to the housing, the rotating means moves proximally with respect to the piston rod; b) when the drive member moves distally the rotating means moves distally, displacing the piston rod towards the distal end of the device.