Methadone: A Substrate and Mechanism-Based Inhibitor of CYP19 (Aromatase)
Methadone: A Substrate and Mechanism-Based Inhibitor of CYP19 (Aromatase)
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DOI：
10.1124/dmd.110.032474
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发表时间：
2010-08-01
影响因子：
3.9
通讯作者：
Flockhart, David A.
中科院分区：
文献类型：
--
作者：
Lu, Wenjie Jessie;Bies, Robert;Flockhart, David A.
外周睾酮通过芳香化酶转化为雌二醇是绝经后妇女内源性雌激素的主要来源。研究表明胎盘芳香化酶能够将美沙酮代谢成其主要代谢物2-亚乙基-1，5-二甲基-3，3-二苯基吡咯烷（EDDP），这使我们检验美沙酮能够作为芳香化酶抑制剂的假设。使用重组人CYP 19，我们研究了美沙酮对睾酮转化为雌二醇的可逆性或机制性抑制的能力。为了测试可逆抑制，外消旋美沙酮或其代谢物EDDP或2-乙基-5-甲基-3，3-二苯基吡咯啉（EMDP）与睾酮在K（m）（4 μ M）下孵育30分钟。为了测试基于机制的抑制，使用外消旋美沙酮（1-1000 μ M）、R-或S-美沙酮（0.5-500 μ M）或EDDP或EMDP（10和100 μ M）进行微粒体预孵育长达30分钟，然后与Vmax浓度（50 μ M）的睾酮孵育。外消旋美沙酮、EDDP和EMDP不作为CYP 19的竞争性抑制剂。美沙酮、EDDP或EMDP与CYP 19预孵育导致时间和浓度依赖性抑制，表明基于机制的反应破坏CYP 19活性。外消旋美沙酮的K（I）和k（inact）值分别计算为40.6 +/- 2.8 μ M和0.061 +/- 0.001 min（-1）。没有观察到立体选择性。美沙酮经CYP 19代谢，在体内可作为CYP 19的有效抑制剂。这些发现可能有助于美沙酮清除率的变化，药物相互作用，并在个别患者中观察到的副作用。
The peripheral conversion of testosterone to estradiol by aromatase is the primary source of endogenous estrogen in postmenopausal women. Studies indicating that placental aromatase is able to metabolize methadone to its primary metabolite, 2-ethylidene-1, 5-dimethyl-3, 3-diphenylpyrrolidin (EDDP), led us to test the hypothesis that methadone is able to act as an inhibitor of aromatase. Using recombinant human CYP19, we examined the ability of methadone to bring about either reversible or mechanism-based inhibition of the conversion of testosterone to estradiol. To test for reversible inhibition, racemic methadone or its metabolite EDDP or 2-ethyl-5-methyl-3, 3-diphenylpyrroline (EMDP) was incubated for 30 min with testosterone at the K(m) (4 mu M). To test for mechanism-based inhibition, microsomal preincubations were performed for up to 30 min using racemic methadone (1-1000 mu M), R- or S-methadone (0.5-500 mu M), or EDDP or EMDP (10 and 100 mu M) followed by incubation with testosterone at a Vmax concentration (50 mu M). Racemic methadone, EDDP, and EMDP did not act as competitive inhibitors of CYP19. Preincubation of methadone, EDDP, or EMDP with CYP19 resulted in time- and concentration-dependent inhibition, indicating a mechanism-based reaction that destroys CYP19 activity. The K(I) and k(inact) values for racemic methadone were calculated to be 40.6 +/- 2.8 mu M and 0.061 +/- 0.001 min(-1), respectively. No stereoselectivity was observed. Methadone is metabolized by CYP19 and may act as a potent inhibitor of CYP19 in vivo. These findings may contribute to variability in methadone clearance, to drug-drug interactions, and to side effects observed in individual patients.