An in-vitro cocktail assay for assessing compound-mediated inhibition of six major cytochrome P450 enzymes

• Published in: Journal of pharmaceutical analysis 2014-08, Vol.4 (4), p.270-278
• Main Authors: Wang, Jing-Jing, Guo, Jian-Jun, Zhan, Jenny, Bu, Hai-Zhi, Lin, Jiunn H.
• Format: Article
• Language: English
• Subjects: Cocktail-probe; Cytochrome P450; Drug screenning; Inhibition assessment; LC–MS/MS; Original; 介导; 体外; 化合物; 抑制作用; 测定法; 细胞色素P450酶; 评估; 鸡尾酒
• ISSN: 2095-1779; 2214-0883
• DOI: 10.1016/j.jpha.2014.01.001

An efficient screening assay was developed and validated for simultaneous assessment of compound-mediated inhibition of six major human cytochrome P450 （CYP） enzymes. This method employed a cocktail of six probe substrates （i.e., phenacetin, amodiaquine, diclofenac, S-mephenytoin, dextromethorphan and midazolam for CYPIA2, 2C8, 2C9, 2C19, 2D6 and 3A4, respectively） as well as individual prototypical inhibitors of the six CYP enzymes in human liver microsomes under optimized incubation conditions. The corresponding marker metabolites （i.e., acetaminophen, N-desethylamodiaquine, 4-OH-diclofenac, 4-OH-S- mephenytoin, dextrorphan and 1-OH-midazolam） in the incubates were quantified using LC-MS/MS methods either by an internal standard （IS） calibration curve or a simpfified analyte-to-IS peak area ratio approach. The results showed that the IC5o values determined by the cocktail approach were in good agreement with those obtained by the individual substrate approach as well as those reported in the literature. Besides, no remarkable difference was observed between the two quantification approaches. In conclusion, this new cocktail assay can be used for reliable screening of compound-mediated CYP inhibition.