Packaging systems used for drug products (pharmaceuticals, biologics) are defined in Packaging and Storage Requirements 〈659〉 and such systems may be constructed from plastic materials and components. Plastics are made of polymers, which can have a range of molecular weights and may contain other substances such as residues from the polymerization process, plasticizers, stabilizers, antioxidants, pigments, and lubricants. The nature and amount of additives in the plastics used for packaging systems are dictated by the type of polymer, the polymer's use, and the process used to convert the polymer into components, containers, or packaging systems.