Absorption, Distribution and Excretion of Alprenolol in Man, Dog and Rat

Abstract

The plasma levels of unchanged alprenolol and its radioactive metabolites were determined in four healthy male volunteers after intravenous and oral administration of 3H‐alprenolol. The mean plasma half‐life was 2.28 hrs and the apparent volume of distribution 2.99 l/kg as determined from the intravenous experiment. In the rat the tissue distribution was studied after intravenous and oral administration by determination of unchanged drug and its radioactive metabolites, in eight different tissues. A high degree of extra‐vascular distribution of the drug was observed, with especially high amounts of unchanged alprenolol in the lung after intravenous administration. In the rat, dog and man the urinary excretion of total radioactivity after intravenous and oral administration of 3 H‐alprenolol was studied. It was concluded that the drug was completely absorbed after oral administration. In man, the drug was almost completely excreted in the urine within 48 hrs mainly as metabolites. In the rat and dog a considerable amount of the drug was excreted in the faeces. From studies in the rat and dog it was demonstrated that this was due to biliary excretion of the drug.