Metabolic Activation of Benzodiazepines by CYP3A4
Metabolic Activation of Benzodiazepines by CYP3A4
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DOI：
10.1124/dmd.108.024521
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发表时间：
2009-02-01
影响因子：
3.9
通讯作者：
Yokoi, Tsuyoshi
中科院分区：
文献类型：
--
作者：
Mizuno, Katsuhiko;Katoh, Miki;Yokoi, Tsuyoshi
细胞色素P450 3A4是肝脏中的主要异构体，代谢了临床常用药物的50%以上。然而，CYP3A4还负责药物的代谢激活，导致肝脏损伤。苯二氮卓类药物被广泛用作安眠药和镇静剂来治疗焦虑，但其中一些会导致人体肝脏损伤。为了阐明苯二氮卓类药物是否被代谢激活，研究了14种苯二氮卓类药物对重组细胞色素P3A4处理的HepG2细胞的细胞毒作用。经100亩M氟硝西潘、尼美西潘或硝西潘处理后，细胞存活率较对照组下降25%以上。相比之下，在其他苯二氮类药物的情况下，CYP3A4和对照超级体之间的细胞活力变化不到10%。这些结果表明，硝基苯二氮卓类药物如氟硝西潘、尼美西潘和硝西潘可被细胞色素P3A4代谢激活，从而产生细胞毒性。为了鉴定活性代谢物，对氟硝西潘和尼美西潘的谷胱甘肽加合物进行了高效液相色谱-串联质谱分析。对氟硝西潘的谷胱甘肽加合物的结构分析表明，氟硝西潘的侧链上有一个氮原子与谷胱甘肽的硫醇共轭。因此，苯二氮卓类药物侧链上硝基的存在可能在细胞色素P3A4的代谢活化中起着至关重要的作用。本研究提示，细胞色素P3A4的代谢活化是硝基苯二氮卓类药物致肝损伤的机制之一。
Cytochrome P450 3A4 is the predominant isoform in liver, and it metabolizes more than 50% of the clinical drugs commonly used. However, CYP3A4 is also responsible for metabolic activation of drugs, leading to liver injury. Benzodiazepines are widely used as hypnotics and sedatives for anxiety, but some of them induce liver injury in humans. To clarify whether benzodiazepines are metabolically activated, 14 benzodiazepines were investigated for their cytotoxic effects on HepG2 cells treated with recombinant CYP3A4. By exposure to 100 mu M flunitrazepam, nimetazepam, or nitrazepam, the cell viability in the presence of CYP3A4 decreased more than 25% compared with that of the control. In contrast, in the case of other benzodiazepines, the changes in the cell viability between CYP3A4 and control Supersomes were less than 10%. These results suggested that nitrobenzodiazepines such as flunitrazepam, nimetazepam, and nitrazepam were metabolically activated by CYP3A4, which resulted in cytotoxicity. To identify the reactive metabolite, the glutathione adducts of flunitrazepam and nimetazepam were investigated by liquid chromatography-tandem mass spectrometry. The structural analysis for the glutathione adducts of flunitrazepam indicated that a nitrogen atom in the side chain of flunitrazepam was conjugated with the thiol of glutathione. Therefore, the presence of a nitro group in the side chain of benzodiazepines may play a crucial role in the metabolic activation by CYP3A4. The present study suggested that metabolic activation by CYP3A4 was one of the mechanisms of liver injury by nitrobenzodiazepines.