Sotalol as a hypotensive agent in pregnancy.

Sotalol, a beta-adrenoceptor blocking drug, was administered to 12 hypertensive pregnant women. The concentration of the drug was assayed in samples of maternal plasma, amniotic fluid and mixed umbilical cord plasma at delivery and, in five mothers who elected to breast feed, in paired samples of maternal plasma and breast milk. Sotalol reduced blood pressure effectively at a mean daily dose of 433.1 +/- 54.1 mg but crossed the placental barrier. The mean maternal: fetal plasma concentration ratio was 1:1.05 and the mean amniotic fluid concentration was 7.0 +/- 2.7 microgram/ml. Delivery occurred at mean gestational age of 37.7 +/- 0.7 weeks; 12 infants were liveborn with a mean weight of 2.8 +/- 0.1 kg and eight of them had no significant neonatal problems. Of the other four, two died from severe congenital anomalies, one had perinatal asphyxia and one mild transient hypoglycaemia. High sotalol concentrations were found in breast milk (mean plasma: milk ratio was 1:5.4) raising the possibility of pharmacological effect in the newborn infant. The results suggest that sotalol adequately controls blood pressure in hypertension complicating pregnancy but because, unlike results from the pregnant ewe, it crosses the human placental barrier it offers no apparent advantages over other beta-adrenoceptor antagonists.