METABOLISM OF IMIPROTHRIN ISOMERS IN RATS - ABSORPTION AND DISTRIBUTION

The absorption and distribution of imiprothrin ([2, 5-dioxo-3-(2-propy nyl)-1-imidazolidinyl] methyl (1R)-cis, trans-chrysanthemate) were stu died by dosing (1R)-trans- or (1R)-cis-[imidazolidinyl-5-C-14]-imiprot hrin orally to male and female rats at 1 (low dose) and 200 mg/kg (hig h dose). C-14-Concentrations in blood reached maxima within 5 hr after dosing the trans-isomer and decreased rapidly thereafter. In the rats treated with the cis-isomer, the concentrations in blood reached a lo wer peak within 9 hr after administration and decreased more gradually as compared with the rats given the trans-isomer. C-14-Concentrations in tissues decreased along with the decreases in the C-14-blood level s in all treatment groups, these in each tissue 72 hr after administra tion of the cis-isomer being higher than in the trans-isomer case. Met abolites identified in the blood were 2, 4-dioxo-1-(2-propynyl)-imidaz olidine (PGH), 5-hydroxy-2, 4-dioxo-1-(2-propynyl)-imidazolidine (PGH- OH) and 2, 4-dioxo-imidazolidine (hydantoin, HYD) in the low dose grou ps, whereas PGH was mainly detected in the high dose groups for both t rans- and cis-isomers. No parent compound was observed in any dose gro up. No marked sex-related differences appeared in the absorption and d istribution of the trans- or cis-isomers within either dose group. The se results suggest that imiprothrin is readily absorbed into the rat b ody, metabolized rapidly and excreted after distribution to tissues.