Disposition of ornidazole and its metabolites during pregnancy.

The disposition of ornidazole and its two major hydroxylated metabolites was studied in five pregnant women (gestational ages 25 5/7 to 38 4/7 weeks) with either chorioamnionitis or pyelonephritis treated with ceftriaxone 2 g, tobramycin 3 mg/kg body weight and ornidazole 1 g all administered once-daily. Two series of blood samples were obtained, the first on the first day of treatment and the second at steady-state on day 5. Local and systemic tolerability of ornidazole was excellent and patients showed complete remission without premature delivery. There was no evidence of ornidazole accumulation, and the pharmacokinetic parameters were very similar to those seen in healthy subjects. The dosage regimen of ornidazole therefore requires no adjustment during pregnancy. Trough concentrations of ornidazole measured at 24 h post dose were above the MIC of sensitive organisms. Children born to the trial patients showed normal initial development and their growth was normal.