TY - JOUR T1 - The physiological disposition and metabolism of enalapril maleate in laboratory animals. JF - Drug Metabolism and Disposition JO - Drug Metab Dispos SP - 15 LP - 19 VL - 10 IS - 1 AU - D J Tocco AU - F A deLuna AU - A E Duncan AU - T C Vassil AU - E H Ulm Y1 - 1982/01/01 UR - http://dmd.aspetjournals.org/content/10/1/15.abstract N2 - N-[1-(S)-carboxy-3-phenylpropyl]-L-alanyl-L-proline (MK-422), is a potent angiotensin I-converting enzyme (ACE) inhibitor, but as a diacid is poorly absorbed in laboratory animals. Enalapril maleate, the monoethyl ester of MK-422, proved to be significantly better absorbed in both rats and dogs. Peak levels of radioactivity in plasma occurred in 30 min in rats and 2 hr in dogs after a single dose of 14C-enalapril maleate (1 mg/kg, po). Rats excreted 26% of the dose in the urine and 72% in the feces in 72 hr; dogs excreted 40% of the dose in the urine and 36% in the feces. After the intravenous dose, the presence of radioactivity in the feces of both species suggested that some biliary excretion had occurred. Absorption was estimated to be 34% in the rat and 61% in the dog. The major metabolite of enalapril maleate in dogs, accounting for 86% of the urine radioactivity, was identified as MK-422 by GC/MS. A procedure was developed for the quantitation of MK-422 and enalapril in plasma and urine by their inhibition of purified ACE. The assays showed that enalapril was absorbed intact in dogs and converted to MK-422 after absorption. ER -