Effect of You‐Gui Yin on the Activities of Seven Cytochrome P450 Isozymes in Rats

You‐Gui Yin (YGY) is a traditional Chinese medicine (TCM) decoction composed of eight Chinese herbs. The interaction between TCM and Western medicine has attracted much attention nowadays. It is therefore necessary to study the clinical application of YGY in combination with Western medicine from the perspective of metabolic enzymes. This study aims to investigate the effect of YGY on the activities of seven CYP450 isozymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4) in rats. Twenty‐four Sprague‐Dawley (SD) rats were randomly divided into four groups: high, middle, and low‐dose YGY‐treated groups and the control group. They were given 13.78, 20.67, and 31 g/kg/d YGY decoction by oral administration and normal saline (10 mL/kg), respectively, for 14 days. Half an hour after the last administration, a mixed probe substrate (1 mg/kg) was administered by tail vein injection. Then, blood was taken from the venous plexus at different time points. The protein expression level of the CYP450 enzymes in the control and treatment groups was determined by western blot. The effect of YGY on the activity of CYP isoenzymes was studied by comparing the plasma pharmacokinetics between the control and treatment groups. Compared with the control group, YGY at a high (31 g/kg) dosage could decrease AUC(0–t), AUC(0–∞) and Cmax of diclofenac, omeprazole, and midazolam by at least 35.4%, while increase CL by at least 88.9%; this revealed that YGY could induce CYP2C9, CYP2C19, and CYP3A4. The results show that when we use You‐Gui Yin decoction in combination with other drugs, especially drugs metabolized by CYP2C9, CYP2C19, and CYP3A4 enzymes, the interaction between drugs needs special attention.