A significant interaction exists between diazepam and infusion fluid containers constructed of PVC plastics. This is attributed to absorption of the drug into the PVC matrix and should preclude the use of this type of container prior to or during infusion of diazepam admixtures. Infusions containing diazepam injection either as a solution (in dextrose 5% or sodium chloride 0.9%) or oil-in-water emulsion (in dextrose 5%) exhibit no significant interaction over 48 h when prepared in polyethylene (Polyfusor) containers. No data were obtained regarding the physical stability of diluted emulsion. The inert nature of polyethylene and an absence of plasticizers or other additives account for a good compatibility with the drug additive. Therefore, diazepam dilutions may be prepared in polyethylene containers as an alternative to glass. However, the interaction with administration sets should not be overlooked when considering these solutions for infusion.