Effect of flow rate and type of i.v. container on adsorption of diazepam to i.v. administration systems

The effect of flow rate and type of i.v. solution container on adsorption of diazepam to i.v. administration systems was studied. Diazepam solutions were prepared in 500 mL of 0.9% sodium chloride injection in glass, polyethylene, and polyvinyl chloride (PVC) containers to a final theoretical concentration of 50 micrograms/mL. PVC administration sets were attached to the containers, and diazepam solution was infused at flow rates of 30, 45, 60, 90, and 120 mL/hr. Solution samples were taken initially and at 0.25, 0.5, 0.75, 1.00, 1.50, 2.00, 3.00, and 4.00 hours after infusion of the first 5 mL of solution through the system. Three infusion trials were performed using each type of container. Adsorption of diazepam to each type of container was evaluated by serial measurements of diazepam concentration over a 168-hour period using five containers of each type. The effect of shaking the container on diazepam adsorption to PVC containers was tested by comparing concentrations in five containers that were shaken during a two-hour period with concentrations in five unshaken containers. Diazepam concentrations were measured spectrophotometrically in duplicate. Diazepam concentrations in glass containers remained unchanged throughout the 168-hour study period; concentrations decreased by about 5% in polyethylene containers and as much as 75% in PVC bags. Shaking increased diazepam adsorption to the PVC container. In the infusion trials, the percentage of diazepam adsorbed increased as flow rate decreased. The amount of diazepam adsorbed to the i.v. administration system was ore dependent on flow rate and infusion time than on the type of container used.(ABSTRACT TRUNCATED AT 250 WORDS)