Enalapril maleate (MK-421), a potent, nonsulfhydryl angiotensin-converting enzyme inhibitor: absorption, disposition, and metabolism in man

Abstract

Animal studies (particularly in dogs) on enalapril maleate have served to predict the patterns of absorption and elimination observed in man. Enalapril is more readily absorbed in man than the active inhibitor form MK-422. Estimates of minimum absorption of enalapril are of the order of 60-70%, based on urinary recovery. Metabolism of enalapril to MK-422 appears to be largely a postabsorptive process. From urinary recovery data, a minimum of 43% of a 10-mg dose of enalapril is available as MK-422. Excretion of enalapril and MK-422 is principally renal. The excellent mass balance obtained in human studies precludes extensive metabolism beyond hydrolysis to MK-422. Data in hand suggest that any metabolism other than to MK-422 is of a trace nature.