Almost half of prescription medications are metabolized by cytochrome P450 3A4 and 3A5. CYP3A4 and 3A5 have significant substrate overlap, and there is currently no way to selectively monitor the activity of these two enzymes, which has led to the erroneous habit of attributing the cumulative activity to CYP3A4. While CYP3A4 expression is ubiquitous, CYP3A5 expression is polymorphic, with large individual differences in CYP3A5 expression level. The CYP3A5 genotype has been shown to alter the pharmacokinetics of drugs in clinical trials. We report the first tool compound capable of determining CYP3A5 activity in biologic samples containing both enzymes. Oxidation of T-5 by CYP3A5 yields an N -oxide metabolite that is over 100-fold selective over CYP3A4. Formation of T-5 N -oxide highly correlates with the CYP3A5 genotype and CYP3A5 expression levels in human liver microsomes and human hepatocytes.
几乎一半的处方药都是通过细胞色素 P450 3A4 和 3A5 代谢的。CYP3A4 和 3A5 的底物有很大的重叠,目前还没有办法选择性地监测这两种酶的活性,这导致了将累积活性归因于 CYP3A4 的错误习惯。CYP3A4 的表达无处不在,而 CYP3A5 的表达则是多态的,CYP3A5 表达
水平的个体差异很大。临床试验表明,CYP3A5
基因型会改变药物的药代动力学。我们报告了第一种能够测定含有两种酶的
生物样本中 CYP3A5 活性的工具化合物。CYP3A5 氧化 T-5 会产生一种 N -氧化物代谢物,其选择性是 CYP3A4 的 100 倍以上。T-5 N -氧化物的形成与人肝微粒体和人肝细胞中的 CYP3A5
基因型和 CYP3A5 表达
水平高度相关。