Described is an autoinjector (1) comprising a case (2), a needle shroud (3) slidably arranged in the case (2), a chassis (8) slidably arranged in the case (2) and rotatably coupled to the needle shroud (3), an outer plunger (7) selectively engaged to the chassis (8), an inner plunger (12) selectively engaged to the outer plunger (7), and a drive spring (6) applying a biasing force to the outer plunger (7). The biasing force is applied to the inner plunger (12) when the inner plunger (12) is engaged to the outer plunger (7). Axial movement of the needle shroud (3) relative to the case (2) causes rotation of the chassis (8) relative to the needle shroud (3). The rotation of the chassis (8) causes the inner plunger (12) to rotate relative to the outer plunger (7) and disengage the outer plunger (7) to remove the biasing force from the drive spring (6) on the inner plunger (12).
