Sorption of various drugs in polyvinyl chloride, glass, and polyethylene-lined infusion containers

The sorption of chloroquine sulfate, diazepam, isosorbide dinitrate, lorazepam, midazolam, nitroglycerin, promethazine hydrochloride, thiopental sodium, and warfarin sodium to three types of containers was studied. Appropriate amounts of the drugs were added to 500 mL of 0.9% sodium chloride injection in polyvinyl chloride (PVC) bags, glass bottles, and Clear-Flex bags composed of a laminate of polyethylene, nylon, and polypropylene. The containers were stored in the dark at room temperature for 24 hours. Samples were taken at various intervals and assayed for drug concentration by high-performance liquid chromatography. There were no appreciable changes in pH after 24 hours, and all the admixtures remained clear and colorless. The potency of chloroquine sulfate, lorazepam, midazolam, promethazine hydrochloride, and thiopental sodium remained unchanged in glass, PVC, and Clear-Flex containers. Diazepam, isosorbide dinitrate, nitroglycerin, and warfarin sodium did not show any sorption to glass bottles and Clear-Flex bags. In PVC bags, however, up to 55% of diazepam, 23% of isosorbide dinitrate, 51% of nitroglycerin, and 24% of warfarin sodium was lost during the 24-hour study period. Diazepam, isosorbide dinitrate, nitroglycerin, and warfarin sodium in 0.9% sodium chloride injection showed a loss of potency when stored in PVC containers for 24 hours at room temperature, but none of the drugs studied lost potency when stored in glass bottles and Clear-Flex bags.