Metabolism of propallylonal

Urinary metabolism of 5-beta-bromoallyl-5-isopropylbarbituric acid (propallylonal, Noctal), was studied in humans after an oral dose of 400 mg. About 25% of the dose was eliminated via kidneys within 48 h. Besides the unchanged drug, six metabolites could be detected. The main metabolic pathway is the hydrolysis of the beta-bromoallyl side chain to an acetonyl function (approximately 15%). The acetonyl function is subsequently reduced to the corresponding alcohol. Loss of water leads to aprobarbital which is partially oxidized to aprobarbital epoxide. Two further metabolites are formed by partial and complete oxidative degradation of the beta-bromoallyl side chain. In contrast to previously published results, no N-methylpropyllalonal could be detected. The plasma protein binding was determined by ultrafiltration (63%). Analysis of propallylonal in plasma and whole blood gave evidence for equal distribution between plasma and erythrocytes.