METABOLISM OF AN IMIDAZOLE FUNGICIDE (PROCHLORAZ) IN THE RAT AFTER ORAL-ADMINISTRATION

The metabolic fate and pathway of the imidazole fungicide prochloraz {1-[N-propyl-N-2-(2,4,6-trichlorophenoxy) ethyl carbamoyl] imidazole} were investigated in the rat after administration of oral single doses with radiolabelled molecules. At both dose levels (50 and 250 mg/kg body weight), virtually all of the ingested [C-14-phenyl]prochloraz was excreted in the urine or faeces within 96 hr, the bulk of excretion occurring between 24 and 48 hr after dosing. Urinary elimination accounted for 61 and 68% of the respective initial doses. Urinary metabolic products were isolated and identified by thin-layer chromatography, gas chromatography or gas chromatography coupled with mass spectrometry analysis. Prochloraz was completely metabolized with no unchanged compound being excreted in the urine. The main biotransformation products in rat urine were 2,4,6-trichlorophenoxyacetic acid and its corresponding alcohol, the latter as a glucuronic acid conjugate. Ring hydroxylation also occurred, with the hydroxy-2,4,6-trichlorophenoxyethanol and hydroxy-2,4,6-trichlorophenoxyacetic acid metabolites excreted in small amounts in the urine. 2,4,6-Trichlorophenol and unconjugated 2,4,6-trichlorophenoxyethanol were identified as minor urinary metabolites.