Concentration of metronidazole in cervical mucus and serum after single and repeated oral doses.

The disposition of metronidazole in cervical mucus and serum after single and repeated oral doses (400 mg) was investigated in six healthy female subjects. Metronidazole reached higher concentrations in serum than cervical mucus after both single and repeated oral doses. Metronidazole concentrations in both cervical mucus and serum were high enough to be trichomonicidal and bactericidal. After oral administration, metronidazole concentrations in cervical mucus are due to diffusion rather than ion trapping.