Metabolism of etidocaine in man

1. Etidocaine and eight metabolites excreted in urine of man have been detected by g.l.c. and investigated by g.l.c.-mass spectrometry. 2. Five metabolites have been identified by comparison with authentic compounds as 2-amino-2'-butyroxylidide, 2-N-ethylamino-2'-butyroxylidide, 2-N-propylamino-2'-butyroxylidide, 2.6-dimethylaniline and 4-hydroxy-2,6-dimethylaniline. 3. The structure of one of the remaining three metabolites is proposed to be 2-methyl-N3-(2,6-dimethylphenyl)-5-ethyl-4-imidazolidinone. 4. The amounts of etidocaine and seven of its metabolites excreted in a 48 h urine following epidural administration to a patient have been estimated. Approx. 31% of the dose was accounted for.