Plasma clearance of propranolol and sotalol and hepatic drug-metabolizing enzyme activity

The role of hepatic drug-metabolizing enzyme activity for plasma propranolol and sotalol levels was investigated in 68 patients with hypertension or angina pectoris by comparing elimination rate with antipyrine kinetics and cytochrome P-450 content in the liver. All subjects were resistant to or had hepatotoxic reaction to previous treatment. Plasma antipyrine clearance and cytochrome P-450 content in biopsies were related to propranolol elimination from plasma, the best fit being obtained with the clearance values. Sotalol plasma clearance was not related to any indirect or direct reflector of the hepatic drug-metabolizing enzyme system. The results demonstrate that plasma clearance of the short-acting beta blocker, propranolol, depends on the activity of hepatic drug-metabolizing enzyme system and indicates a trial with a drug such as sotalol which is not dependent on liver metabolizing capacity.