Placental transfer of metronidazole and tinidazole in early human pregnancy after a single infusion.

Concentrations of metronidazole and tinidazole were analysed in mother's serum, placental tissue and foetal tissue after a single intravenous infusion of 500 mg of either drug in 21 patients who underwent a first trimester legal abortion. At the time of the evacuation (60 min from the start of the infusion) the concentrations of metronidazole and tinidazole in serum were 13.6 +/- 0.6 micrograms/ml and 13.2 +/- 0.4 micrograms/ml, respectively. In foetal tissue the concentrations of metronidazole and tinidazole reached 66% and 58%, and in placental tissue 26% and 37%, of the respective serum values.