Described is a reuse prevention mechanism comprising a guidance arm (10) with a pin (9) engaged in a guidance contour (8) adapted to control movement of the guidance pin (9), and a blocking part adapted to block access to a needle (12) in a fourth position (P4) of the reuse prevention mechanism (3). The guidance contour (8) is adapted to constrict linear movement of the reuse prevention mechanism (3) in a direction (D) from a first position (P1) to a third position (P3).
