Metabolism of Terallethrin in Rats

Abstract

In single oral or subcutaneous administration of ¹⁴C-terallethrin labeled at the CO-group of the acid moiety to male and female Sprague-Dawley rats at the dose of 5mg/kg, ¹⁴C was rapidly absorbed, and distributed mainly into intestines, liver and kidney. Thereafter, the ¹⁴C was rapidly excreted into the urine and feces. During the 7 days following administration, 49 to 62% of the dosed ¹⁴C was found in the urine, 38 to 50% was in the feces, and totally 97 to 100% was recovered in the excreta. ¹⁴C Residue levels in 23 (female) to 24 (male) tissues were less than 0.09μg terallethrin equivalents/g tissue. Whole-body autoradiography also showed that ¹⁴C tissue residues were very low in the rat body. Tlc analysis showed that more than 18 metabolites were present in the urine and feces. One fifth to 0.3% of the dose of the parent compound was found in the feces. Major metabolites resulted from oxidation of one the gem-dimethyl group attached to the cyclopropane ring and cleavage of the carboxyl ester linkage. Ester metabolites hydroxylated at the 2-methyl and 3-allyl groups of the allethronyl moiety were also found. Hydroxylation at the gem-dimethyl and 3-allyl groups was dominant in male rats, whereas carboxylic acid formation from the gem-dimethyl group was dominant in female rats. No qualitative and quantitative differences in the metabolites were found between oral and subcutaneous administrations.