Pharmacokinetics of metronidazole and its major metabolite after a high intravenous dose

The pharmacokinetics of metronidazole (M) and hydroxy-metronidazole (OH-M) were determined in 8 healthy volunteers after a single dose of 1.5 g metronidazole given as an intravenous infusion during 50 min. High-pressure liquid chromatography was used for the assays. The serum concentration determined 1 h after the start of infusion was 40.21 +/- 6.54 mg/1. The peak concentrations of the metabolite were observed after 8-12 h. The serum concentrations of M and OH-M were detectable throughout the 48 h monitored. The serum half-life of M was 7.6 h and of OH-M 13.3 h. The terminal phase distribution volume was 43.2 lit and the total body clearance 4.0 lit./h. The prophylactic use of 1.5 g of metronidazole given as a single intravenous dose 1 h prior to surgery is supported by the pharmacokinetic assessments in this study.