Abstract: A syringe is provided for injecting pharmaceuticals into patients and withdrawing liquid samples from patients. The syringe includes a barrel having proximal and distal ends. A plunger is reciprocably disposed in the barrel to drive fluid from the distal end when moving in that direction. The syringe further includes an end wall for closing the distal end, a cannula on the end wall, and an assembly for connecting the end wall to the plunger so that movement toward the proximal end of the barrel will move the cannual within the barrel. A frangible section provides a sealed connection between the end wall and the distal end of the barrel. The plunger is proportioned and shaped to engage the end wall and break the frangible section when the plunger is pushed toward the distal end of the barrel with a predetermined force.