Metabolism of the Insecticide Isofenphos in Rats

Abstract

Distribution, metabolism and excretion of [O-ethyl-1-¹⁴C] isofenphos were examined in rats. When rats were orally administered with ¹⁴C-isofenphos, the ¹⁴C-compounds were distributed over the whole body 6hr after administration and decreased gradually with time. ¹⁴C-Compounds in the liver were persistent. Greater part of radiocarbon excreted from rats was recovered from the urine, and smaller part from the feces and the expired air. When metabolites in the urine and feces were partitioned between benzene and water, most of radiocarbon was recovered from the water fraction, and only small part from the benzene fraction and unextractable residues. Aminoisofenphos and isofenphos-oxon were identified as benzene soluble metabolites, and six metabolites were identified as water soluble metabolites, which include O-ethyl hydrogen phosphoramidate, O-ethyl hydrogen isopropylphosphoramidothioate and others. The results suggested that cleavage of P-O-aryl linkage took place dominantly in isofenphos metabolism in rats compared with that of P-N linkage.