Availability of diazepam from plastic containers.

The effect of plastic intravenous containers and volume-control administration sets on diazepam availability was studied. Solutions of diazepam in dextrose 5% in water and in 0.9% sodium chloride were prepared in plastic burette chambers and polyvinyl chloride (PVC) bags. Diazepam concentration was measured spectrophotometrically for (1) samples taken from the burette chamber and from the end of the administration set, (2) samples prepared in glass beakers and then infused through plastic administration sets with 0.5-micron filters, (3) samples prepared in PVC bags, and (4) sections of the PVC bags and volume-control sets in which diazepam solutions were prepared and infused. Two hours after admixture, diazepam concentration was significantly reduced in the burette chamber (p less than 0.05). Diazepam concentration was reduced by about 55% after infusion through administration sets (p less than 0.0005) and after two hours of storage in PVC bags. About 24% of the diazepam concentration was recovered from the volume-control set (none was detected in the filter) and 49-56% was recovered from the PVC bags. Admixture of diazepam solutions in plastic containers and administration through plastic administration sets will significantly reduce their diazepam concentrations.