Injection devices

Injection device arranged to actuate a syringe (29) when the syringe (29) is located therein, the device a housing (1) for the syringe (29), a cover (15) of needle attached to the front end comprising the housing (1) and movable before use between retracted and extended positions, an element (17) driving releasable to move from a rear inside the housing (1) to a forward position position for pushing the syringe forward to project its needle (30) beyond the cover (15) of the retracted needle and then propel a dose through the needle (30), characterized by elements (12) positioning in the housing (1) to capture the element (17) driver in its forward position reached after the propulsion of the dose, and wherein the element (17) captured impeller is arranged to block retraction of the cover (15) needle from its extended position.