Regioselective biotransformation of midazolam by members of the human cytochrome P450 3A (CYP3A) subfamily.
Regioselective biotransformation of midazolam by members of the human cytochrome P450 3A (CYP3A) subfamily.
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DOI：
10.1016/0006-2952(94)90543-6
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发表时间：
1994-04
影响因子：
5.8
通讯作者：
J. Gorski;J. Gorski;S. Hall;David R. Jones;M. Vandenbranden
中科院分区：
文献类型：
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作者：
J. Gorski;J. Gorski;S. Hall;David R. Jones;M. Vandenbranden
使用人肝微粒体和纯化的CYP 3A 4和CYP 3A 5研究了细胞色素P4503 A4（CYP 3A 4）、CYP 3A 5和含CYP 3A 7的胎肝微粒体代谢咪达唑仑的能力。在初始速率条件和高底物浓度（400 μM咪达唑仑）下，18份人肝微粒体样品中咪达唑仑1′-和4-羟基化的变异性分别为30倍和16倍。排除从既往接受过巴比妥类药物治疗的患者中分离的两份样本后，1′-和4-羟基化的个体间变异性分别降低至10.5倍和6.0倍。6份胎仔肝微粒体样本显示1′-羟基咪达唑仑和4-羟基咪达唑仑形成率均存在10倍变异。仅含CYP 3A 4的成人样本和胎肝样本中咪达唑仑生成4-羟基咪达唑仑和1′-羟基咪达唑仑的速率高度相关（r2分别为0.99和0.97，P< 0.01）。仅含CYP 3A 4的成人样本中咪达唑仑（400 μM）形成1′-羟基咪达唑仑和4-羟基咪达唑仑的速率显著相关红霉素N-脱甲基化能力（P < 0.01）（r2分别为0.95和0.92）、6β-羟基化睾酮（r2分别为0.96和0.96）和样品的CYP 3A 4含量（r2分别为0.89和0.86）。与仅含有CYP 3A 4或CYP 3A 7的样品相比，含有CYP 3A 5和CYP 3A 4的微粒体样品显示1′-羟基咪达唑仑与4-羟基咪达唑仑的比值显著更大（P < 0.001）。在由二月桂酰磷脂酰胆碱、细胞色素b 5和NADPH-细胞色素P450还原酶组成的复溶系统和NADPH再生系统中，纯化的CYP 3A 5显示与含CYP 3A 4的复溶系统相比，1′-羟基咪达唑仑形成速率高2倍，4-羟基咪达唑仑形成速率相似。总之，CYP 3A 4、CYP 3A 5和含CYP 3A 7的胎仔微粒体催化咪达唑仑的1′-和4-羟基化，这些代谢产物的比例指示CYP 3A形式。
The capabilities of cytochrome P4503A4 (CYP3A4), CYP3A5, and fetal hepatic microsomes containing CYP3A7 to metabolize midazolam were investigated using human hepatic microsomes and purified CYP3A4 and CYP3A5. Under initial rate conditions and high substrate concentration (400 μM midazolam), variability among eighteen human liver microsomal samples was 30- and 16- fold for 1′- and 4-hydroxylation of midazolam, respectively. Exclusion of two samples isolated from patients previously administered barbiturates reduced the inter-individual variability to 10.5- and 6.0-fold for 1′- and 4-hydroxylation, respectively. Six fetal hepatic microsomal samples showed 10-fold variation in both 1′-hydroxymidazolam and 4-hydroxymidazolam formation rates. The rates of formation of 4-hydroxymidazolam and 1′-hydroxymidazolam from midazolam by adult samples containing only CYP3A4 and by fetal liver samples were highly correlated (r2=0.99 and 0.97, P< 0.01, respectively). The rates of formation of 1′-hydroxymidazolam and 4-hydroxymidazolam from midazolam (400 μM) by adult samples that contained only CYP3A4 were correlated significantly (P < 0.01) with the ability of the samples to N-demethylate erythromycin (r2=0.95 and 0.92, respectively), 6β-hydroxylate testosterone (r2=0.96 and 0.96, respectively), and the CYP3A4 content of the samples (r2=0.89 and 0.86, respectively). Microsomal samples containing CYP3A5 in addition to CYP3A4 exhibited a significantly greater ration of 1′-hydroxymidazolam to 4-hydroxymidazolan compared with samples containing only CYP3A4 or CYP3A7 (P < 0.001). Purified CYP3A5 in a reconstituted system, consisting of dilauroylphosphatidylcholine, cytochromeb5, and NADPH-cytochrome P450 reductase, and an NADPH-regenerating system displayed a 2-fold greater rate of 1′-hydroxymidazolam formation and a similar rate of 4-hydroxymidazolam formation compared with a reconstituted system with CYP3A4. In conclusion, CYP3A4, CYP3A5, and fetal microsomes containing CYP3A7 catalyze 1′- and 4-hydroxylation of midazolam with the ratio of these metabolites indicative of the CYP3A form.