Modern biopharmaceutical drug molecules are often complex protein structures that need to maintain the molecular structure in order to convey full potency. With biologics, any alteration of the 3-D structure could lead to loss of activity or even to immunogenic reactions in the patient. Proteins can be disrupted by interactions with the container closure or with leachables. West FluroTec® lamination was chosen for NovaPure® plungers to reduce the interaction between the drug product and elastomer material. This includes less adsorption to the plunger surface as well as reduction of the leachables profile of the plunger, helping to maintain the stability of complex molecules.