EP2489386A1 — Auto-injector

USPTO Abstract

The invention relates to an auto-injector (1) for administering a dose of a liquid medicament (M), comprising: - an elongate tubular case (12), - a carrier subassembly comprising a tubular carrier (7) slidably arranged inside the case (12), the carrier (7) adapted to contain a syringe (3) with a hollow injection needle (4), a drive spring (8) and a plunger (9) for forwarding load of the drive spring (8) to a stopper (6) of the syringe (3), wherein the syringe (3) is lockable for joint axial translation with the carrier (7), wherein the drive spring (8) acts between the carrier (7) and the plunger (9), wherein the plunger (9) in an initial state is locked to the carrier (7) by a ramped engagement to the carrier (7) and by being prevented from rotating out of this ramped engagement depending on a relative longitudinal position of the carrier (7) in the case (12), wherein the plunger (9) is arranged to be released for rotating out of the ramped engagement upon the needle (4) reaching at least nearly a predefined injection depth on translation of the carrier (7) in the proximal direction (P) for advancing the needle (4) beyond a proximal end of the auto-injector (1).