Pharmacokinetics of propranolol during pregnancy

Propranolol, a beta-adrenoceptor blocking drug, was administered to 6 healthy pregnant volunteers between 32 and 36 weeks gestation and when at least 6 weeks postpartum. On both occasions, subjects were given propranolol 120 mg orally or 10 mg intravenously in randomised order with a minimum washout period of 1 week. Propranolol was assayed in plasma by gas-liquid chromatography with electron-capture detection and the pharmacokinetic parameters were investigated. There were no significant alterations in elimination half-life, clearance or apparent volume of distribution per kilogram antenatally compared with postnatally: bioavailability was also unchanged. It is concluded that the disposition of propranolol is not altered during pregnancy.