The metabolism of 2- and 3-hydroxyacetanilide. Determination of metabolic products by liquid chromatography/electrochemistry.

The metabolism of 2- and 3-hydroxyacetanilide was examined in incubations with mouse liver microsomes. Metabolic products were determined by a comparison of both chromatographic and electrochemical properties with that of reference materials. Using this technique, 3-hydroxyacetaminophen and 2-acetamidohydroquinone were positively identified as microsomal metabolites of 3-hydroxyacetanilide. Incubation of 2-hydroxyacetanilide with liver microsomes resulted in the formation of 2-acetamidohydroquinone. Deacetylation products, ortho- and meta-aminophenol were observed but were apparently formed through NADPH-independent processes. Tentative identifications were made for the formation of sulfhydryl adducts from 3-hydroxyacetanilide, 2-acetamidohydroquinone, and 2-hydroxyacetanilide but not from 3-hydroxyacetanilide. The microsomal metabolism was compared with in vivo metabolism through the analysis of urine from mice administered 200 mg/kg (ip) dosages of the hydroxyacetanilides. The parent compounds and their dihydroxylated metabolites were excreted primarily as sulfate and glucuronide conjugates. Conjugated o-aminophenol was detected in urine following 2-hydroxyacetanilide administration, but m-aminophenol was not observed in urine from mice receiving the meta isomer. Mercapturates of the above compounds were not detected in any of the urines.