A pre-filled syringe for sterile medication fluid injection includes a syringe barrel with rotationally symmetric cylindrical bore, having a distal end and a proximal end a syringe piston with rotationally symmetric external shape a backstop mounted at the proximal end of the syringe barrel with an opening that is rotationally asymmetric about the axis through the syringe barrel a push rod to move the syringe piston inside the syringe barrel, wherein at least one portion of the push rod is rotationally asymmetric about the axis through the syringe barrel, and upon rotation, the rotationally asymmetric portion of the push rod is aligned with the rotationally asymmetric opening of the backstop and a seal component to cover the distal end of the syringe barrel.
