Objective: To study the effect of Scutellaria extract to cytochrome P450 enzymes CYP1A2 CYP3A4

CYP2E1 and CYP2C19. Method: To establish an RP-HPLC method for the study of 4 probe drugs in rats plasma. The rats are divided in 2 groups randomly. One group were given Scutellaria extract once daily

another received normal saline once daily as the blank control. After 10 days of treatment

the rats were given 4 probe drugs by tail intravenous injection and the plasma were obtained at 0

5

10

15

30

15

60

180

360

540

720 min. The plasma concentration of 4 probe drugs was determined by RP-HPLC. The pharmacokinetic parameters were calculated by Kinetica 5.0. Result: The metabolism of dapsone

chlorzoxazone and omeprazole are slowed down significantly while the T1/2of all 4 probe drugs were increased. The MRT0→∞of chlorzoxazone and omeprazole were increased significantly. Conclusion: Scutellaria extract tended to be the inhibitor of CYP1A2

CYP3A4

CYP2E1 and CYP2C19. But CYP3A4 and CYP2E1 were affected significantly.