Abstract: AIM: To investigate the effect of Modified Xiaoyao pill on CYP2C19, and provide foundation for clinical drug using. METHODS: Twenty volunteers were divided into two groups according to CYP2C19^*2 gene type, ten for WW gene type and ten for MM gene type. Omeprazole used as probe drug of CYP2C19, the effect of Modified Xiaoyao pill on the activity of CYP2C19 were investigated. Genetic classification was fulfilled by pyrosequencing method, and the blood concentration of probe drug and its metabolic product were determined by HPLC-MS/MS. RESULTS: The volunteers took Modified Xiaoyao pill for two weeks, AUC_0-12 was used as the standard of the activity of CYP2C19. The activity value was 5.7±1.6 before drug and 6.0±1.7 after drug using. So the activity of CYP2C19 was increased after drug using, t-test was used for comparison, there was no remarkable difference between the data. CONCLUSION: Modified Xiaoyao pill has no obvious affection on the activity of CYP2C19.

Key words: Modified Xiaoyao pill, CYP2C19, Pyrosequencing