Metronidazole in breast milk.

Breast milk concentrations of metronidazole were assayed in 3 women who had been treated with a single 2.0-g dose for trichomoniasis. Highest concentrations of the drug were found 2 and 4 hours after administration, and they declined over the next 12 to 24 hours. It appears that if breast-feeding is withheld for 12 to 24 hours after the dose, infants will be exposed to a greatly reduced amount of metronidazole. As the use of metronidazole in nursing mothers is currently not recommended, this may be the regimen of choice for the treatment of trichomoniasis in lactating women.