Mouse hepatic metabolites of ketoconazole: Isolation and structure elucidation

Abstract Oxidation, cleavage and degradation of the imidazole and piperazine rings, O-dealkylation, and aromatic hydroxylation are the reported pathways of ketoconazole (KC) metabolism. Metabolites were examined in hepatic extracts from male Swiss Webster mice treated with KC (350 mg kg −1 po × 7 days) in a 0.25% gum tragacanth suspension at 10 ml kg −1 . Livers were collected 24 h after the last dose and stored at −70°C. A mixture of chloroform/methanol extracts of liver homogenates were dried under vacuum and methanol extracts of the residue were chromatographed by a series of preparative and analytical HPLC techniques. Structure assignments were made by NMR and MS/MS techniques. It was demonstrated that KC was biotransformed to a number of products. Nine were isolated and seven identified as exclusive products of the biotransformation of the 1-acetylpiperazine moiety of KC. This substituent was biotransformed to the following: piperazine (de- N -acetyl ketoconazole, DAKC), N -carbamylpiperazine, N -formylpiperazine, 2,3-piperazinedione, 2-formamidoethylamine, ethylenediamine and amine. The 1 H-NMR and MS data suggested that the remaining two metabolites were products resulting from the oxidation of the imidazole ring.