Abstract: OBJECTIVE: To investigate the efficacy of Tianma(Rhizoma Gastrodiae) and Gouteng(Ramulus Uncariae Rhynchophyllae cum Uncis) on cytochrome P450(CYP450) enzyme activities in rats.METHODS: A cocktail strategy was followed to evaluate the influence of Tianma(Rhizoma Gastrodiae) and Gouteng(Ramulus Uncariae Rhynchophyllae cum Uncis) on the activities of CYP450 isoforms(CYP1A2, CYP3A4, CYP2E1, CYP2C19, CYP2C9,CYP2D6), which were determined by changes in the pharmacokinetic parameters of six probe drugs, theophylline, dapsone, chlorzoxazone,omeprazole, tolbutamide and dextromethorphan.Study groups included, Control group(CG), Tianma(Rhizoma Gastrodiae) group(TM), Gouteng(Ramulus Uncariae Rhynchophyllae cum Uncis) group(GT)and Tianma Gouteng(Gastrodia Uncaria) group(TMGT).RESULTS: No significant differences between Tianma(Rhizoma Gastrodiae) and control groups were found. Compared with the control group, in the Gouteng(Ramulus Uncariae Rhynchophyllae cum Uncis) group both the AUC and t1/2 of dapsone and tolbutamide were reduced, whereas the CL(clearance rate) of dapsone and tolbutamide were increased. Compared with the control group, in the Tianma Gouteng group, the AUC and t_(1/2) of dapsone and tolbutamide were reduced, the CL of dapsone and tolbutamide were increased, and the AUC and t_(1/2) of chlorzoxazone were increased and the CL of chlorzoxazone was reduced.CONCLUSION: Tianma(Rhizoma Gastrodiae) has no significant effect on the six CYP450 subtypes. The activities of CYP3A4 and CYP2C9 were increased by Gouteng(Ramulus Uncariae Rhynchophyllae cum Uncis). The activities of CYP3A4 and CYP2C9 were increased, whereas the activity of CYP32 E1 was reduced by combined Tianma(Rhizoma Gastrodiae)and Gouteng(Ramulus Uncariae Rhynchophyllae cum Uncis).

Key words: Gastrodiae Elata;;Ramulus Uncariae Cum Uncis;;cytochrome P-450 enzyme system;;cocktail probe drug