Gas Chromatographic-Mass Spectrometric Studies on the Metabolic Fate of Ethotoin in Man

D L Bius, W D Yonekawa, H J Kupferberg, F Cantor, K H Dudley

Drug Metab Dispos. Jul-Aug 1980;8(4):223-9.

PMID: 6105055


Unchanged ethotoin and 11 metabolic products of ethotoin were detected in the urine of subjects (2 men and 1 woman) receiving ethotoin. Nine of these products were identified by comparison of their retention times and mass spectra with those of authentic synthetic samples. Hydroxylation of the hydantoin ring at the 5-position produced 5-hydroxyethotoin and 5-hydroxy-5-phenylhydantoin. Aryl hydroxylation resulted in the formation of p-hydroxyethotoin, o-hydroxyethotoin, m-hydroxyethotoin, 3-methoxy-4-hydroxyethotoin, and 3,4-dihydroxyethotoin. Most of these were excreted as the glucuronide conjugate. A dihydrodiol of ethotoin and 3-ethyl-5-hydroxy-5-(4-hydroxyphenyl)hydantoin were isolated along with unchanged ethotoin and 5-phenylhydantoin. 2-Phenylhydantoic acid was also isolated and was shown to have the (R)(-)-configuration.

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