Isoform-selective metabolism of mianserin by cytochrome P-450 2D.

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Chow T, Hiroi T, Imaoka S, Chiba K, Funae Y

Isoform-selective metabolism of mianserin by cytochrome P-450 2D.

Drug Metab Dispos. 1999 Oct;27(10):1200-4.

PubMed ID

10497148 [ View in PubMed

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Abstract

The involvement of cytochrome P-450 (CYP) 2D isoforms in the metabolism of mianserin and the stereoselectivity of their catalytic activities were investigated by using five CYP2D isoforms (CYP2D1, 2D2, 2D3, 2D4, and 2D6). Using RS-mianserin as a substrate, we found that five CYP2D isoforms had similar levels of 8-hydroxylation activity. However, N-demethylation activity differed among the isoforms; CYP2D3 and 2D4 efficiently demethylated RS-mianserin compared with the other three isoforms. N-Oxidation activity was specific to CYP2D1 although its level was relatively low. Another metabolite, assigned as 8-hydroxy-N-desmethylmianserin by liquid chromatography/mass spectrometry analysis, was formed by CYP2D4 and 2D6. The metabolism exhibited stereoselectivity. CYP2D1 and 2D4 selectively 8-hydroxylated the R(-)-enantiomer, and CYP2D6 predominately N-demethylated R(-)-enantiomer. N-Oxidation by CYP2D1 was specific to R(-)-enantiomer. In conclusion, CYP2D isoforms are involved in several metabolic pathways of mianserin acting in an isoform-specific manner. Stereoselectivity of the catalytic activities was clearly observed in the reactions of CYP2D1, 2D4, and 2D6.

DrugBank Data that Cites this Article

Drug Enzymes

Drug	Enzyme	Kind	Organism	Pharmacological Action	Actions
Mianserin	Cytochrome P450 2D6	Protein	Humans	Unknown	Substrate	Details