Drug interactions with medical plastics.

Knowledge about drug interactions with plastic materials used in medical and surgical practice is at an elementary stage. Information that has appeared so far on the sorption of drugs to intravenous fluid containers, delivery sets, syringes, or other plastic apparatus has highlighted that polyvinyl chloride (PVC) is the major offender in this respect. Fortunately, in only a few cases is this sorption phenomenon and loss of drug from fluid likely to present a clinical hazard; in most instances, methods are available to prevent or overcome the problem, providing it is recognized. Current information suggests that the following drugs may exhibit clinically significant sorption to plastic materials: insulin, glyceryl trinitrate (nitroglycerin), diazepam, chlormethiazole, vitamin A acetate, isosorbide dinitrate, and a miscellaneous group of drugs including some phenothiazines, warfarin sodium, hydralazine hydrochloride, and thiopentone sodium. In addition, chloroquine binds strongly to glass and to cellulose acetate, but seemingly not to plastics. Brief details of these interactions and their management are given, together with some preliminary information and warnings on drug interactions (e.g., epinephrine, rifampicin) with hydrophilic contact lenses. The latter interactions may cause irreversible coloration of the lenses.