T. Uchida, T. Usui, T. Teramura
May 1, 1993
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Drug metabolism and disposition: the biological fate of chemicals
Abstract
The metabolism of 1,3-bis[[1-cycloheptyl-3-(p-dimethylamino- phenyl)ureido]methyl]benzene dihydrochloride (YM17E) in rat liver microsomes was investigated. After incubation of YM17E with rat liver microsomes in the presence of NADPH, a significant amount of YM17E was consumed and several products appeared. The structures of these products were identified by thermospray-linked LC/MS. By comparison of fragmentation patterns between these products and authentic compounds, five metabolites were eventually identified. All five metabolites--termed M1, M2-a, M2-b, M3, and M4--were sequentially formed through N-demethylation. The formation of these metabolites was NADPH-dependent, and was inhibited by SKF-525A, metyrapone, and carbon monoxide, which are inhibitors of cytochrome P-450. These results suggest that N-demethylation of YM17E is one of the main pathways of its biotransformation, and that this metabolism is catalyzed by cytochrome P-450-mediated monooxygenase.