Pharmacokinetics of pentamidine in Sprague-Dawley rats in late pregnancy.

To our knowledge, placental transfer of pentamidine has not been previously studied in vivo. In the present study, the pharmacokinetics of pentamidine were analyzed in late gestation (18 days) among Sprague-Dawley rats. Pentamidine's kinetics were assessed in the following maternal compartments over a 12-hour period in 16 timed-pregnant rats: serum, liver, and kidney. Placentas were also analyzed for pentamidine concentration as were fetal brain, liver, and kidney tissues. Significant placental transfer of the drug was found, with pentamidine reaching all fetal compartments studied. Notably, by the twelfth hour fetal brain tissue achieved pentamidine concentrations that were not significantly different from those of maternal serum at the second hour of the experiment. This is an interesting observation because adult mouse and rat brains were found to be unexposed to the drug.