von Bahr C, Spina E, Birgersson C, Ericsson O, Göransson M, Henthorn T, Sjöqvist F
Biochem Pharmacol. 1985 Jul 15;34(14):2501-5. doi: 10.1016/0006-2952(85)90533-7.
The 2-hydroxylation of desmethylimipramine (DMI) correlates strongly with the 4-hydroxylation of debrisoquine (D) both in human volunteers and in vitro comparing human liver microsomes from different individuals. D competitively inhibits the 2-hydroxylation of DMI in vitro suggesting that DMI is hydroxylated by the 'debrisoquine hydroxylase' which is under monogenic control in man. We have characterized the effect of drugs on the hydroxylation of DMI in human liver microsomes by measuring the formation of 2-OH-DMI with HPLC using fluorescence detection. Amitriptyline, nortriptyline and metoprolol inhibited the hydroxylation of DMI competitively indicating interaction with the catalytical site for DMI 2-hydroxylation. Antipyrine and amylobarbitone at concentrations similar to their Km-values for metabolism did not inhibit DMI-hydroxylation. Thus, for these compounds there was a good correspondence between the drugs' capacity to inhibit DMI 2-hydroxylation competitively in vitro and their apparent metabolism by the 'debrisoquine hydroxylase' in vivo in man. Thioridazine, chlorpromazine, quinidine and quinine also inhibited DMI-hydroxylation competitively. Thioridazine was an unusually potent inhibitor (apparent inhibition constant Ki = 0.75 microM). Quinidine was also an unusually potent inhibitor (Ki = 0.27 microM) and much more efficient than its isomer quinine (Ki = 12 microM). Theophylline could inhibit DMI hydroxylation but with atypical kinetics. We suggest that this simple DMI in vitro test as well as earlier described inhibition tests with debrisoquine, sparteine and bufuralol can be used to screen if drugs interact with the 'debrisoquine hydroxylase' in human liver.
在人类志愿者体内以及在体外比较不同个体的人肝微粒体时，去甲丙咪嗪（DMI）的2-羟基化与异喹胍（D）的4-羟基化密切相关。D在体外竞争性抑制DMI的2-羟基化，这表明DMI是由人类单基因控制的“异喹胍羟化酶”进行羟基化的。我们通过使用荧光检测的高效液相色谱法测量2-羟基-DMI的形成，来表征药物对人肝微粒体中DMI羟基化的影响。阿米替林、去甲替林和美托洛尔竞争性抑制DMI的羟基化，表明它们与DMI 2-羟基化的催化位点相互作用。在与其代谢的Km值相似的浓度下，安替比林和戊巴比妥并不抑制DMI的羟基化。因此，对于这些化合物，其在体外竞争性抑制DMI 2-羟基化的能力与其在人体内被“异喹胍羟化酶”进行的表观代谢之间存在良好的对应关系。硫利达嗪、氯丙嗪、奎尼丁和奎宁也竞争性抑制DMI的羟基化。硫利达嗪是一种异常强效的抑制剂（表观抑制常数Ki = 0.75 microM）。奎尼丁也是一种异常强效的抑制剂（Ki = 0.27 microM），且比其异构体奎宁（Ki = 12 microM）更有效。茶碱可以抑制DMI的羟基化，但具有非典型动力学。我们建议，这种简单的DMI体外试验以及早期描述的异喹胍、司巴丁和布非洛尔抑制试验，可用于筛选药物是否与人肝中的“异喹胍羟化酶”相互作用。
