The metabolism of 2-chloro-1-(2′,4′-dichlorophenyl)vinyl diethyl phosphate (Chlorfenvinphos) in the dog and rat

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Abstract
A single oral dose of [Cl4] Chlorfenvinphos to rats is quantitatively eliminated in 4 days. Rats do not show a sex difference in the elimination pattern and show only a small degree of biological variation in the total excretion data. Of the label 87.2% is excreted in the urine (67.5% in the first day after dosage), 11.2% in the feces and 1.4% in the expired gases; less than 0.9% of C14 is present in the gut and contents after 4 days. After oral administration of [C14]Chlorfenvinphos to dogs, 94.0% (91.8-97.6%) of the Cl4 is excreted in the urine and feces during 4 days. Dogs do not show a sex difference in the pattern of elimination, and excretion of radioactivity in the urine is very rapid 86.0% of C14 during 0-24 hr. Chlorfenvinphos is completely metabolized in rats and dogs: unchanged Chlorfenvinphos is absent from the urine and from the carcass, when elimination is complete. In rats, 2-chloro-l-(2[image],4[image]-dichlorophenyl)vinyl ethyl hydrogen phosphate accounts for 32.3% of a dose of Chlorfenvinphos, [1-(2[image],4[image]-dichlorophenyl)ethyl [beta]-D-glucopyranosid]uronic acid for 41.0%, 2,4-dichloromandelic acid for 7.0%, 2,4-dichlorophenylethanediol glucuronide for 2.6% and 2,4-dichlorohippuric acid for 4.3%; in dogs, 2-chloro-l-(2[image],4[image]-dichloro-phenyl)vinyl ethyl hydrogen phosphate accounts for 69.6%, [l-(2[image],4[image]-dichlorophenyl)ethyl [beta]-D-glucopyranosid] uronic acid for 3.6%, 2,4-dichloromandelic acid for 13.4% and 2,4-dichlorophenylethanediol glucuronide for 2.7%. Dogs and rats show a species difference in the rate of excretion of C14 in the urine, and in the proportions of the metabolites, with the exception of 2,4-dichlorophenylethanediol glucuronide, that are excreted in the urine. Alternative explanations for the latter species difference are suggested. 2-Chloro-l-(2[image],4[image]-dichloro-phenyl)vinyl ethyl hydrogen phosphate and 2,4-dichlorophenacyl chloride probably lie on the main metabolic pathway of Chlorfenvinphos, since, in common with that insecticide, they give rise to [l-(2[image],4[image]-dichloro-phenyl)ethyl [beta]-D-glucopyranosid]uronic acid and 2,4-dichloromandelic acid as major metabolites in the urine. The proposed scheme for the metabolism of Chlorfenvinphos represents a detoxication mechanism.

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