METABOLISM OF PYRIPROXYFEN IN RATS .1. ABSORPTION, DISPOSITION, EXCRETION, AND BIOTRANSFORMATION STUDIES WITH [PHENOXYPHENYL-C-14]PYRIPROXYFEN

摘要

Male and female rats were given a single oral dose of [phenoxyphenyl-C-14]pyriproxyfen [4-phenoxyphenyl (R,S)-2-(2-pyridyloxy)propyl ether] at 2 (low dose) or 1000 (high dose) mg/kg. C-14 was rapidly excreted into feces and urine, with the former route predominating (about 90% of the dose). Peak C-14 concentrations in blood, kidney, liver, and other tissues except for fat occurred 2-8 h. after administration, being 0.4, 0.4, 2.5, and <0.2 mu g of pyriproxyfen equivalents/g of tissue (ppm), respectively. Peak C-14 concentration in fat occurred 12-24 h after administration, being 0.3-0.5 ppm. C-14 tissue residues on the seventh day were below 0.02 and 10 ppm for the low and high doses, respectively. The major metabolic reactions were hydroxylation at the 2- or 4-position of the terminal phenyl ring, hydroxylation at the 5-position of the pyridyl ring, cleavage of the ether linkages, and conjugation of the resultant phenols with sulfuric acid. No marked sex-related differences were observed-for C-14 excretion or C-14 tissue residues. However, a slight sex-related variation was found for the extent of metabolic reactions.