Effect of bacterial vaginosis on the pharmacokinetics of misoprostol in early pregnancy

Abstract

BACKGROUND: Misoprostol has been shown to be an effective agent for cervical ripening and termination of early pregnancy especially when administered vaginally. Our objective was to evaluate whether bacterial vaginosis (BV) affected the pharmacokinetics of vaginally administered misoprostol during early pregnancy. METHODS: Ten women with BV and 10 healthy women requesting medical abortion up to 9 weeks of pregnancy were administered 200 mg mifepristone followed 24-48 h later by a single dose of 800 μg misoprostol vaginally. Blood samples were taken before (0 h) and 0.5, 1, 2, 3 and 4 h after misoprostol administration. Misoprostol acid was determined in serum samples using liquid chromatography/tandem mass spectrometry. RESULTS: All women with BV had a vaginal pH > 4.7. The mean bioavailability measured as the area under the curve (AUC) and maximum concentration (Cmax) appeared higher in the control than in the BV group (1458.7 versus 878.1 pg h/ml) and (630.7 versus 342.5 pg/ml), respectively, but did not achieve statistical significance and there was no other significant difference in the pharmacokinetics between the two groups. However, if two women with vaginal pH > 4.7 were excluded from the control group the difference in AUC240 (1359 versus 878.1 pgh/ml) reached statistical significance (P = 0.048). CONCLUSIONS: BV had an effect on pharmacokinetics of vaginally administered misoprostol in early pregnancy. However, the results should be interpreted with caution due to the small sample size and marked individual variations. © The Author 2011. Published by Oxford University Press. All rights reserved.