Sertraline N-demethylation is catalyzed by multiple isoforms of human cytochrome P-450 in vitro.
Sertraline N-demethylation is catalyzed by multiple isoforms of human cytochrome P-450 in vitro.
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发表时间：
1999-07
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通讯作者：
Kaoru Kobayashi;T. Ishizuka;N. Shimada;Y. Yoshimura;K. Kamijima;K. Chiba
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作者：
Kaoru Kobayashi;T. Ishizuka;N. Shimada;Y. Yoshimura;K. Kamijima;K. Chiba
舍曲林是一种新型的选择性5-羟色胺再摄取抑制剂类抗抑郁剂，在人体内被广泛代谢为去甲基舍曲林。我们利用混合的人肝微粒体和表达的细胞色素P-450(CYP)亚型鉴定了参与舍曲林N-去甲基化的细胞色素P-450(CYP)亚型。人肝微粒体内舍曲林N-去甲基化的Eadie-Hofstee图谱是单相的。估算的Michaelis-Menten动力学参数为：Km=18.1+/-2.0微米，Vmax=0.45+/-0.03nmol/min/mg蛋白质，Vmax/Km=25.2+/-4.3微l/min/mg蛋白质。在接近表观Km值的20微米底物浓度下，磺胺苯唑(CYP2C9抑制剂)和三唑仑(CYP3A底物)可使人肝微粒体N-去甲基化活性降低20~35%，而美苯妥因(CYP2C19底物)或奎尼丁(CYP2D6底物)的抑制作用较弱。抗CYP2B6抗体对舍曲林N-脱甲基化活性的抑制作用为35%。在所研究的所有表达CYP的亚型中都检测到舍曲林N-去甲基化活性。其中，CYP2C19、CYP2B6、CYP2C9-Arg、CYP2D6-Val和CYP3A4均表现出较高的活性。根据表达的CYP亚型的Vmax/Km和其在人肝微粒体中的含量估算其对CYP的贡献时，分别为35、29、14、13和9%。结果表明，至少有5种不同亚型的CYP参与了人肝微粒体舍曲林的N-去甲基化，且各亚型对总代谢的贡献率不超过40%。因此，同时服用一种抑制特定CYP亚型的药物不太可能导致舍曲林血浆浓度显著增加。
Sertraline, a new antidepressant of the selective serotonin reuptake inhibitor class, is extensively metabolized to desmethylsertraline in humans. We identified the cytochrome P-450 (CYP) isoforms involved in sertraline N-demethylation using pooled human liver microsomes and cDNA-expressed CYP isoforms. Eadie-Hofstee plots for the sertraline N-demethylation in human liver microsomes were monophasic. The estimated Michaelis-Menten kinetic parameters were: KM = 18.1 +/- 2.0 microM, Vmax = 0.45 +/- 0.03 nmol/min/mg of protein, and Vmax/KM = 25.2 +/- 4.3 microl/min/mg of protein. At the substrate concentration of 20 microM, which approximated the apparent KM value, sulfaphenazole (CYP2C9 inhibitor) and triazolam (CYP3A substrate) reduced the N-demethylation activities by 20 to 35% in human liver microsomes, whereas the inhibition induced by mephenytoin (CYP2C19 substrate) or quinidine (CYP2D6 inhibitor) was marginal. The anti-CYP2B6 antibody inhibited the sertraline N-demethylation activities by 35%. Sertraline N-demethylation activities were detected in all cDNA-expressed CYP isoforms studied. In particular, CYP2C19, CYP2B6, CYP2C9-Arg, CYP2D6-Val, and CYP3A4 all showed relatively high activity. When the contributions of CYP2D6, CYP2C9, CYP2B6, CYP2C19, and CYP3A4 were estimated from the Vmax/KM of cDNA-expressed CYP isoforms and from their contents in pooled human liver microsomes, the values were found to be 35, 29, 14, 13, and 9%, respectively. The results suggest that at least five isoforms of CYP (CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP3A4) are involved in the sertraline N-demethylation in human liver microsomes and that the contribution of any individual isoform does not exceed 40% of overall metabolism. Therefore, concurrent administration of a drug that inhibits a specific CYP isoform is unlikely to cause a marked increase in the plasma concentration of sertraline.