Biochemical Studies on the Mode of Action of Pyrethroidal Insecticides

Part I. Metabolic Fate of Phthalthrin in Mammals

Abstract

For the purpose of elucidating the metabolic pathways of phthalthrin (Neo-Pynamin®) in mammals, radioactive phthalthrin was administered orally to male Wistar rats. Approximately 95% of the administered carbon-14 was recovered in the excreta during five days after treatment. About half of the radioactivity was observed to be excreted into urine and the remainder was found in feces unabsorbed. The content of phthalthrin in the tissues was very low; less than 1% of the radioactivity several hours after treatment when the tissues contained highest radioactivity. Intact phthalthrin was not present and only minute amount of N-(hydroxyvmethyl)-3, 4, 5, 6-tetrahydrophthalimide, 3, 4, 5, 6-tetra-hydrophthalimide or cyclohexane-l, 2-dicarboximide was dectected in urine. The major metabolite excreted was tentatively identified as 3-hydroxy-cyclohexane-l, 2-dicarboximide. From the results slow absorption of phthalthrin from the intestinal tract and rapid degra-dation of the compound in animal body were presumed.