Quantitative contribution of CYP2D6 and CYP3A to oxycodone metabolism in human liver and intestinal microsomes
Quantitative contribution of CYP2D6 and CYP3A to oxycodone metabolism in human liver and intestinal microsomes
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DOI：
10.1124/dmd.32.4.447
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发表时间：
2004-04-01
影响因子：
3.9
通讯作者：
Shen, DD
中科院分区：
文献类型：
--
作者：
Lalovic, B;Phillips, B;Shen, DD
羟考酮经过N-脱甲基化生成去甲羟考酮，O-脱甲基化生成羟吗啡酮。使用一组重组人P450鉴定了能够介导羟考酮氧化为羟吗啡酮和去甲羟考酮的细胞色素P450（P450）亚型。CYP 3A 4和CYP 3A 5对羟考酮N-去甲基化的活性最高; CYP 3A 5的固有清除率略高于CYP 3A 4。CYP 2D 6的O-去甲基化活性最高。在从5个人肝脏制备的微粒体中观察到两种氧化反应的多酶Michaelis-Menten动力学。酮康唑的抑制作用表明，CYP 3A是羟考酮N-脱甲基的高亲和力酶;在低底物浓度下，酮康唑可抑制> 90%的去甲羟考酮形成。CYP 3A介导的去甲羟考酮形成显示平均Km为600 +/- 119 μ M，Vmax范围为716 - 14523 pmol/mg/min。低亲和力酶的贡献不超过N-去甲基化总固有清除率的8%。奎尼丁抑制表明，CYP 2D 6是O-去甲基化的高亲和力酶，平均Km为130 +/- 33 μ M，Vmax范围为89 - 356 pmol/mg/min。低亲和力酶的活性占O-去甲基化总固有清除率的10 - 26%。平均而言，在5种肝微粒体制剂中，去甲羟考酮形成的总固有清除率是羟吗啡酮形成的8倍（10.5穆尔/min/mg vs 1.5穆尔/min/mg）。人肠粘膜微粒体的实验表明，与肝微粒体相比，N-脱甲基活性较低（20 - 50%），O-脱甲基活性可忽略不计，这预示肠粘膜在羟考酮首过氧化代谢中的作用极小。
Oxycodone undergoes N-demethylation to noroxycodone and O-demethylation to oxymorphone. The cytochrome P450 (P450) isoforms capable of mediating the oxidation of oxycodone to oxymorphone and noroxycodone were identified using a panel of recombinant human P450s. CYP3A4 and CYP3A5 displayed the highest activity for oxycodone N-demethylation; intrinsic clearance for CYP3A5 was slightly higher than that for CYP3A4. CYP2D6 had the highest activity for O-demethylation. Multienzyme, Michaelis-Menten kinetics were observed for both oxidative reactions in microsomes prepared from five human livers. Inhibition with ketoconazole showed that CYP3A is the high affinity enzyme for oxycodone N-demethylation; ketoconazole inhibited > 90% of noroxycodone formation at low substrate concentrations. CYP3A-mediated noroxycodone formation exhibited a mean K-m of 600 +/- 119 muM and a V-max that ranged from 716 to 14523 pmol/mg/min. Contribution from the low affinity enzyme(s) did not exceed 8% of total intrinsic clearance for N-demethylation. Quinidine inhibition showed that CYP2D6 is the high affinity enzyme for O-demethylation with a mean K-m of 130 +/- 33 muM and a V-max that ranged from 89 to 356 pmol/mg/min. Activity of the low affinity enzyme( s) accounted for 10 to 26% of total intrinsic clearance for O-demethylation. On average, the total intrinsic clearance for noroxycodone formation was 8 times greater than that for oxymorphone formation across the five liver microsomal preparations (10.5 mul/min/mg versus 1.5 mul/min/mg). Experiments with human intestinal mucosal microsomes indicated lower N-demethylation activity ( 20 - 50%) compared with liver microsomes and negligible O-demethylation activity, which predict a minimal contribution of intestinal mucosa in the first-pass oxidative metabolism of oxycodone.