Studies on the fate of 14C-labeled oxolinic acid, 3

Isolation and characterization of the urinary metabolites of oxolinic acid, a new antimicrobial agent, were undertaken with rats. At an oral dose of 10 mg/kg of 14C-oxolinic acid, about 34% of the administered radioactivity was excreted in the urine within 24 hr and about 95% of this urinary radioactivity was accounted for in its metabolites. The major metabolite (43.5%) in the urine was a conjugate of 1-ethyl-1,4-dihydro-6,7-dihydroxy-4-oxo-3-quinolinecarboxylic acid with an unknown compound. This indicates that a cleavage of the methylenedioxy moiety of oxolinic acid had occurred. Other metabolites were 6- and 7-monomethoxy derivatives of the above catechol and their conjugates with either glucuronic acid of a ninhydrin-positive compound. This means that this catechol metabolite could be methylated at either of the two hydroxy groups. From these results the metabolic pathways of 14C-oxolinic acid in rats seem to involve oxidation of the methylenedioxy moiety, o-methylation and conjugation with glucuronic acid or other two unidentified compounds, one of which was ninhydrin positive. (author)