米氮平在鼠肝微粒体中的体外代谢研究

Research of metabolism of antidepressant mirtazapine on mice liver microsome in vitro

目的:通过不同诱导剂预处理鼠肝,研究米氮平在肝微粒体中的代谢主要受何种酶影响,同时研究米氮平对介导其自身代谢的P450酶亚型是否有影响,为米氮平的临床合理应用提供科学依据。方法:将米氮平与不同诱导剂诱导的鼠肝微粒体进行体外孵育代谢,以乙腈中止反应,样品用25%氨水碱化后以环己烷提取。用RPHPLC测定剩余的米氮平含量,流动相为甲醇水(含10mmol·L-1NH4AC,5mmol·L-1SDS,pH3.5)6238(VV),检测波长为307nm。结果:本文测定方法回收率高,日内和日间精密度均良好,符合生物样本检测要求。苯巴比妥诱导的鼠肝微粒体对米氮平的代谢具有明显的催化作用,利福平也有一定的催化能力,米氮平诱导的鼠肝微粒体与对照组对米氮平的代谢无明显差异。结论:由苯巴比妥诱导的P450酶亚型(主要为细胞色素P4503A4)和利福平诱导的P450酶亚型(主要为细胞色素P4502C92C19,同时也对P4503A4有一定的诱导作用)在米氮平的体外代谢中起着重要作用;而米氮平诱导组对于米氮平代谢无明显影响,预示米氮平对介导其自身代谢的P450酶亚型无明显的诱导或抑制作用。

AIM: To identify the isoforms of cytochrome P450 (CYP) involved in the metabolism of mirtazapine and the influence of mirtazapine on the metabolism of mirtazapine. METHODS: Mirtazapine was incubated with rats liver microsomes induced by different inducers, and the reaction was terminated by acetonitrile. The sample was added 25% ammonia water and extracted with cyclohexane, and the determination was performed by RP-HPLC with the mobile phase of methanol-water (including 10 (mmol·L^(-1)) NH_4AC, 5 (mmol·L^(-1)) SDS, pH (3.5)) 6238(v/v). RESULTS: The assay was linear from (75.3) to 565 (μmol·L^(-1)) for mirtazapine in rat hepatic microsomal incubates. The livers induced by phenobarbital were catalyzed and livers induced by rifampicin also showed more active performance, while the livers induced by rats had no significant difference between two groups. CONCLUSION: P450 3A4 induced by phenobarbital as well as rifampicin is crucial in the metabolism of mirtazapine. And P450 2C9/2C19 induced by rifampicin may also interfere the metabolism of mirtazapine. Mirtazapine has no obvious effect on the isoforms responsible for its metabolism of mirtazapine.