Phenotyping Studies Of Main Cytochrome P450 Enzymes Using An In Vivo Cocktail And Its Application To Rapid Assessment Of The Induction Of Cytochrome P450 Of Traditional Chinese Medine

Objectives Cytochrome P450 (CYP450) is a superfamily of enzymes, which can be induced or inhibited by concomitant drugs. As a result, abrupt changes of the blood concentration of the drugs can occur due to itself or its co-administered agent. These types of changes can alter a drug's safety and efficacy, and lead to drug-drug interaction. Three in vivo Cocktail approaches were established for phenotyping studies of main cytochrome P450 activities, and were applied to rapidly assess the induction of CYP450 by 46 traditional Chinese medicines (TCM). This study of the effect of CYP450 enzymes by TCM can guide clinical reasonable medication of TCM and extend our knowledge basis for the theory of the compound recipe of TCM.Methods (1)A method was established for the simultaneous determination of six CYP450 probe drugs, caffeine (CYP1A2), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1) and midazolam (CYP3A4), in rat blood. The pharmacokinetics parameters of the probe drugs were used as indexes to establish an in vivo Cocktail phenotypic rat modelâ… for simultaneous assessment of the activities of six main CYP450 enzymes. The induction of the six CYP450 enzymes by dexamethasone was investigated using modelâ… . (2)A method was established for the simultaneous determination of six CYP450 probe drugs, caffeine (CYP1A2), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1) and midazolam (CYP3A4), in mouse blood. The pharmacokinetics parameters of the probe drugs were used as indexes to establish an in vivo Cocktail phenotypic mouse modelâ…¡for simultaneous assessment of the activities of six main CYP450 enzymes. The induction of the six CYP450 enzymes by dexamethasone, phenobarbital and rifampicin was investigated using modelâ…¡. (3)A LC-MS/MS method was described for rapid determination of five CYP450 probe drugs and their relevant metabolites in mouse blood. The five specific probe substrates/metabolites are caffine/paraxanthine (CYP1A2), tolbutamide/4-hydroxytolbutamide (CYP2C9), omeprazole/5-hydroxyomeprazole (CYP2C19), dextromethorphan/dextrorphan (CYP2D6) and midazolam/1'-hydroxymidazolam (CYP3A4). Phenotypic metablic ratios of the probe drugs were used as indexes to establish an in vivo Cocktail phenotypic mouse modelâ…¢for simultaneous assessment of the activities of five main CYP450 enzymes. In addition, the induction of the five CYP450 enzymes of dexamethasone and phenobarbital was investigated using Modelâ…¢. (4)Modelâ…¢was utilized for rapid induction screening of the five major CYP450 enzymes(CYP1A2,2C9,2C19,2D6,2E1 and 3A4) of 46 tradictional Chinese medicines which are commonly used in clinic. Results (1)AUC and Cmax of the six probe drugs after oral administration of dexamethasone for one week were significantly decreased compared with pre-administration. This indicated dexamethasone had an induction effect on CYP1A2,2C9,2C19,2D6,2E1 and 3A4. (2)The results suggested dexamethasone induced the CYP1A2,2C9,2C19,2D6,2E1,3A4, phenobarbital induced the CYP1A2,2D6,3A4, and rifampicin induced the CYP1A2,2C9,2C19,2D6,3A4. (3)Comparisons of the metabolic ratios of probe drugs between supplementation of dexamethasone or phenobarbital and control indicated that dexamethasone induced the activity of CYP3A4,2C19,2C9, and phenobarbital induced the activity of CYP1A2,3A4,2C19,2C9. (4)The results suggested Danggui induced CYP2C19, Huangqin induced CYP2C19, Jianghuang induced CYP2C19, Wuweizi induced CYP3A4, Yinchen induced CYP2C19, Yinxingye induced CYP2C9, Qinghao induced CYP2D6 and 3A4, Gouteng induced CYP2C9 and 3A4, Mutong induced CYP2D6, Duzhong induced CYP2C9,2C19 and 3A4, Chaihu induced CYP2D6,2C9 and 3A4, Baizhu induced CYP2C9, Daqingye induced CYP1A2 and 2C9, Zexie induced CYP2C19, Chenpi induced CYP1A2, Chuanwu induced CYP3A4 and Fuzi induced CYP2C19. Conclusions: The Cocktail approach can be used to rapidly assess the activities of CYP450 enzymes, and thus to be an effective tool for high-throughput screening of drugs and help to herb-drug interactions research. The data demonstrated many traditional Chinese medicines could induce the CYP450 activity to a different extent, and speed up the metabolism of itself or its coadministrated drugs, and result in a change of the therapeutic effect of the drugs. Besides, this study will guide the rational medication of TCM and help in the theory of the compound recipe of TCM research.