Sorptive loss of diazepam and nitroglycerin from solutions to three types of containers

The sorption of diazepam and of nitroglycerin were studied in glass, polyethylene, and polyvinyl chloride containers with two injectionable solutions. Diazepam and nitroglycerin were diluted to final concentrations of 200 micrograms/ml and 90 micrograms/ml, respectively, in 0.9% sodium chloride or 5% dextrose injection in glass, polyethylene, and polyvinyl chloride containers and stored under room light at 25 +/- 1 degrees C. Samples were taken at 0, 2, 4, 6, and 24 hours after injection of drug. Diazepam was assayed with a spectrophotometer; nitroglycerin was assayed with an automatic chemical analyzer. All solutions were visually compatible. Diazepam and nitroglycerin concentrations remained constant in both i.v. solutions in glass and polyethylene containers. Concentrations of both drugs were reduced in polyvinyl chloride bags to less than 90% of initial within four hours after admixture. No degradation products of either drug were found. It is concluded that sorption of diazepam and nitroglycerin occurs when the drugs are in polyvinyl chloride bags, and that glass and polyethylene containers are superior for these admixtures.