Transfer of propranolol and sotalol across the human placenta. Their effect on maternal and fetal plasma renin activity.

Eighty milligrams of propranolol or sotalol was administered orally to two groups of 8 parturients who were to undergo elective cesarean section. This was performed 3 hours after drug administration. The transplacental passage of both drugs was registered in each patient. The maternal concentration of propranolol was approximately four times that in the umbilical circulation, while the sotalol level in maternal circulation was twice that in the umbilical circulation. The administration of beta-adrenoceptor antagonists caused a significant decrease in maternal plasma renin activity. After these doses of beta blockers, no difference in the plasma renin activity was found in the umbilical circulation, when compared with the previous normal values at cesarean section.