A locking mechanism is provided for use with a reservoir and a reservoir holder so as to prevent unwanted tampering with the reservoir. The mechanism comprises a main body with an aperture that is coupled to the reservoir. A hinged flange is provided on the main body. The flange folds inwards at the pivot point provided by the hinge, toward the aperture of the main body, allowing the mechanism to pass over the ferrule of the reservoir. Once the mechanism is placed over the cartridge, the flange folds toward the reservoir at the pivot point, flexing away from the main body. The flange rests against the underside of the reservoir ferrule, thereby retaining the reservoir within the locking mechanism. The locking mechanism may be for use with either a disposable or a reusable delivery device.
