Drug Adsorption

Non-polar, sparingly soluble drugs stored in plastic containers tend to partition into the plastic container wall. A classical example is nitroglycerin. Nitroglycerin has low water solubility, approximately 0.1%, which suggests that it has high non-polar solubility. Indeed, if nitroglycerin in aqueous solution is placed in a polyvinylchloride IV bag (non-polar medium) or is delivered through a polyvinylchloride IV set, there is little doubt that with time the drug will be lost by adsorption to the plastic. This seems to be true also for vitamin A acetate, warfarin, methohexital, terbutaline, lorazepam, and insulin. Since the dosing of nitroglycerin is critical, it should be dispensed in glass IV bottles and infused with a special, non-adsorbing infusion set.