Maternal-fetal transfer of saquinavir studied in the ex vivo placental perfusion model

OBJECTIVE: This study was undertaken to determine the placental transfer of the human immunodeficiency virus protease inhibitor saquinavir. STUDY DESIGN: An ex vivo perfused human placental cotyledon model was used. Ten placental perfusion studies were performed, with concentrations of saq uinavir in the maternal compartment ranging from 322 to 2197 ng/mL (within reference therapeutic ranges). Drug concentrations were determined by high- performance liquid chromatography. RESULTS: The mean (+/- SD) fetal transfer rate of saquinavir was 1.8% +/- 1 .6%, and the mean ( SID) clearance index was 0.05 +/- 0.05. A mean ( SD) of 1.6% +/- 3.1% of the perfused saquinavir was retained by the cotyledon. Th e small amount of saquinavir that crossed the placenta corresponded to the fraction not bound to human serum albumin. CONCLUSION: The low rate of placental transfer of saquinavir suggests that use of this antiretroviral drug by pregnant women may not lead to significa nt exposure of the fetus.