Syringe assemblies having a passive disabling system to prevent reuse areprovided. In one embodiment, the passivedisabling system activates after completion of an injection cycle. Anexemplary syringe assembly (100) incorporates a stopper (160)and plunger rod (140) attached in a manner to prevent users from disassemblingthe syringe prior to completion of the injectioncycle. The barrel (120) may also include an annular extension or collar (400)that extends from the proximal end (129) of the barrel.In a specific configuration, the annular extension at least partiallyenvelopes a portion of the thumb press (300) to prevent the userfrom accessing the thumb press and moving the plunger rod in a proximaldirection Syringe assembles of one or more embodimentsalso include visual indicators and markers (500) indicating whether a syringeassembly is used or the plunger rod is locked withinthe barrel.
