The present invention provides a plunger head designed to absorb the increased pressure applied against it during heat sterilization to thereby minimize or prevent plunger head movement during autoclaving. The present invention provides the plunger head as part of a syringe or as part of a kit including a syringe, a plunger rod, and optionally, a pharmaceutical product fluid such as a contrast media. Some pharmaceutically-tolerable gas may be provided in the syringe with the product fluid.
