Vasoactive Effects and Placental Transfer of Nifedipine, Celiprolol, and Magnesium Sulfate in the Placenta Perfused in Vitro

Objective: The aim of this study was to assess the transfer of nifedipine, celiprolol, and magnesium sulfate across the human placenta and to evaluate their effects on placental vascular tone. Methods: Dual in vitro placental perfusion system in an isolated lobule of the human placenta. Results: Nifedipine and celiprolol had no effect on vascular tone in the fetal chorionic artery. Magnesium sulfate infusion (30 min) resulted in a sustained fall of 32% (SD 8%) in perfusion pressure. The mean (SD) placental clearances of nifedipine, celiprolol, and magnesium sulfate were 0.54 (0.20) mL/min, 0.34 (0.15) mL/min, and 0.79 (0.32) mL/min, respectively. Conclusions: Magnesium sulfate has a vasodilatory effect on the fetal placenta. Because of its limited placental transfer, celiprolol, a beta(1)-selective adrenoceptor antagonist with minor vasodilating and bronchodilating effects, may be safer for the fetus than other beta-blockers used in pregnancy.