Propranolol disposition after acute myocardial infarction.

Serum propranolol concentration, elimination t 1/2, and protein binding were studied after a combined intravenous/oral regimen in 20 subjects with myocardial infarction (MI) and 15 with chest pain (CP). There was 1000% interindividual variation in propranolol concentrations in each group. In the MI group, mean total serum propranolol concentrations were greater than 100 nmol/l, except at 7 hr, when there was a trough not present in subjects with CP. Mean elimination t 1/2 s in subjects with MI (7.2) and CP (7.4 hr) did not differ. There were significantly higher alpha 1-acid glycoprotein concentrations and reduced percent unbound propranolol 27 hr after infarction. Free propranolol concentrations were lower 7 and 11 hr after dosing in the MI group, but concentrations thereafter were of the same order as those in subjects with CP. The only significant difference in any of the hemodynamic measurements was at 7 hr, when blood pressure was higher in the MI group. We conclude that propranolol kinetics were altered in subjects with MI and suggest that the regimen could be improved by increased propranolol dosage at commencement of therapy.