(EN) 21 ACTIVATION MECHANISM FOR DRUG DELIVERY DEVICE ABSTRACT A drug delivery device includes a housing, an injection assembly at least partially disposed in the housing, a shield, and a drive assembly at least partially disposed in the housing and coupled with the injection assembly and the shield. The shield has an extended position where at least a proximal end thereof extends a distance beyond a proximal end of the housing. The injection assembly includes a needle or cannula having an endpoint. Upon moving the shield axially towards the distal end of the housing a predetermined distance, a retraction profile commences whereby the drive assembly administers a medicament via the injection assembly. A peak resistance force is exerted within approximately the first 12mm of axial movement of the shield. Fig. 1