THE METABOLISM AND EXCRETION OF PROCHLORAZ, AN IMIDAZOLE-BASED FUNGICIDE, IN THE RAT

1. Following oral administration of prochloraz (1-[N-propyl-N-2-(2,4,6-trichlorophenoxy)ethylcarbamoyl]imidazole) at 100 mg/kg body weight to rats, the compound underwent extensive metabolism, the primary route appearing to be opening of the imidazole ring followed by hydrolysis of the alkyl chain. The major metabolites were 2,4,6-trichlorophenoxyacetic acid and 2-(2,4,6-trichlorophenoxy)ethanol, which is present mainly as a glucuronide conjugate. Ring hydroxylation occurred to produce several minor metabolites. No unchanged prochloraz was excreted in the urine. 2. Tissue residues 96 h after dosing were generally < 1 mg prochloraz equivalents/kg tissue. The highest residues were found in the liver (2.8-5.1 mg prochloraz equivalents/kg tissue) and kidney (1.5-2.1 mg prochloraz equivalents/kg tissue), the principal organs of metabolism and excretion. Residues in female rats were generally slightly higher than those found in males. 3. The metabolites were quantitatively excreted within 96 h, with > 50% of the dosed radioactivity being found in the 0-24 h excreta. Urinary excretion accounted for 65% dose in male and 41% in female rats, respectively.