Syringe assemblies having a passive disabling system to prevent reuse are provided.In one embodiment, the passive disabling system activates after completionof an injection cycle. An exemplary syringe assembly incorporates a stopperand plunger rod attached in a manner to prevent users from disassembling the syringeprior to completion of the injection cycle. The barrel may also include an annularextension or collar that extends from the proximal end of the barrel. In a specificconfiguration, the annular extension at least partially envelopes a portionof the thumb press to prevent the user from accessing the thumb press and movingthe plunger rod in a proximal direction Syringe assemblies of one or more embodimentsalso include visual indicators or markers indicating whether a syringe assemblyis used or the plunger rod is locked within the barrel.
