Detection of a new N-oxidized metabolite of flutamide, N-[4-nitro-3-(trifluoromethyl)phenyl]hydroxylamine, in human liver microsomes and urine of prostate cancer patients
Detection of a new N-oxidized metabolite of flutamide, N-[4-nitro-3-(trifluoromethyl)phenyl]hydroxylamine, in human liver microsomes and urine of prostate cancer patients
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DOI：
10.1124/dmd.105.008623
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发表时间：
2006-05-01
影响因子：
3.9
通讯作者：
Yamazoe, Y
中科院分区：
文献类型：
--
作者：
Goda, R;Nagai, D;Yamazoe, Y
氟替卡松（2-甲基-N-[4-硝基-3-（三氟甲基）苯基]-丙酰胺）是一种非甾体类抗雄激素药物，用于治疗前列腺癌，但偶尔与肝功能障碍相关。在本研究中，使用人肝微粒体和10种重组人细胞色素P450（P450）亚型研究了氟替卡松的代谢，包括可能的反应性毒性代谢产物的形成。2-羟基芴醇（OH-芴醇）和4-硝基-3-（三氟甲基）苯胺（FLU-1）是芴醇在人肝微粒体中的主要代谢产物。CYP 1A 1/1A 2抑制剂椭圆藤碱可显著抑制OH-氟替卡松的形成，且主要由重组CYP 1A 2催化。FLU-1也由OH-芴醇产生，但其代谢速率远低于芴醇。羧酸酯酶抑制剂双-（对硝基苯基）磷酸可完全抑制人肝微粒体中氟替卡松形成FLU-1。检测到一种新的代谢产物N-[4-硝基-3-（三氟甲基）苯基]羟胺（FLU-1-N-OH）是FLU-1与人肝微粒体反应的产物，并通过与合成标准品进行比较进行鉴别。加入CYP 3A 4抑制剂咪康唑可显著抑制FLU-1-N-OH的形成，并由重组CYP 3A 4介导。此外，FLU-1-N-OH主要以结合物（葡糖苷酸/硫酸盐）的形式在前列腺癌患者接受氟替卡松治疗后3小时收集的尿液中检出。然而，在总共29名患者中，FLU-1-N-OH的形成在有和没有肝功能异常的患者之间没有差异。FLU-1-N-OH的尿排泄与肝脏疾病之间缺乏明显的相关性，这可能表明在氟替卡松肝毒性机制中涉及其他未知因素。
Flutamide (2-methyl-N-[4-nitro-3-(trifluoromethyl) phenyl]- propanamide), a nonsteroidal antiandrogen, is used in the treatment of prostate cancer but is occasionally associated with hepatic dysfunction. In the present study, the metabolism of flutamide including the formation of the possible reactive toxic metabolites was investigated using human liver microsomes and 10 isoforms of recombinant human cytochrome P450 ( P450). 2-Hydroxyflutamide (OH-flutamide) and 4-nitro-3-( trifluoromethyl) phenylamine (FLU-1) were the main products of flutamide metabolism in human liver microsomes. The formation of OH-flutamide was markedly inhibited by ellipticine, an inhibitor of CYP1A1/1A2, and was mainly catalyzed by the recombinant CYP1A2. FLU-1 was also produced from OH-flutamide, but its metabolic rate was much less than that from flutamide. An inhibitor of carboxylesterase, bis-(p-nitrophenyl) phosphoric acid, completely inhibited the formation of FLU-1 from flutamide in human liver microsomes. A new metabolite, N-[4-nitro-3-(trifluoromethyl) phenyl] hydroxylamine (FLU-1-N-OH), was detected as a product of the reaction of FLU-1 with human liver microsomes and identified by comparison with the synthetic standard. The formation of FLU-1-N-OH was markedly inhibited by the addition of miconazole, an inhibitor of CYP3A4, and was mediated by recombinant CYP3A4. Furthermore, FLU-1-N-OH was detected mostly as the conjugates (glucuronide/ sulfate) in the urine of prostate cancer patients collected for 3 h after treatment with flutamide. The formation of FLU-1-N-OH, however, did not differ between patients with and without abnormalities of hepatic functions among a total of 29 patients. The lack of an apparent association of the urinary excretion of FLU-1-N-OH and hepatic disorder may suggest the involvement of an additional unknown factor in the mechanisms of flutamide hepatotoxicity.