Bioavailability of three formulations of intravenous diazepam.

It has been generally assumed that the bioavailability of different formulations of intravenous diazepam is identical. In a within-subject crossover study using eight healthy volunteers, we have found that both the initial and the overall plasma diazepam levels are significantly lower after both emulsion (Diazemuls) and micelle preparations than after an organic formulation (Valium). These findings are relevant to the interpretation of the results of past, present and future clinical studies involving intravenous diazepam. The studies with Valium and Diazemuls confirm the clinical impression of the lesser potency of the latter formulation.