A syringe assembly comprising a barrel for containing one or more medicaments, a narrowed outlet for allowing the expulsion of said one or more medicaments from said barrel through said outlet； and a stopper disposed in the barrel defining and separating a first volume and a second volume within the syringe assembly. The stopper comprises a permanent seal fluidly sealing the stopper to the barrel about the entire perimeter of the stopper intermediate the first volume and second volume, and a channel bypassing the permanent seal, the channel having a first opening in fluid communication with the second volume and a second opening selectively sealed from the first volume by a resilient seal. The resilient seal is moveable between a sealing configuration and an open configuration to selectively seal the channel from the first volume, where in the sealing configuration the resilient seal fluidly seals the stopper to the barrel so as to fluidly isolate said second opening of the channel from the first volume, and in the open configuration the second opening of the channel is in fluid communication with the first volume. The resilient seal is moveable from the sealing configuration to the open configuration upon fluid pressure in the first volume or second volume exceeding a first pressure threshold.
