Objective: An HPLC-MS-MS assay for simultaneous determination of phenacetin

tolbutamide

omeprazole

metoprolol tartaric acid

chlorzoxazone and testosterone simultaneously in rat plasma was established to evaluate Glycyrrhizae Radix on the activity of cytochrome P450 enzymes (CYP1A2

CYP2C9

CYP2C19

CYP2D6

CYP2E1 and CYP3A4). Method: The separation was carried out on a Hanbon C18 column (2.0 mm×150 mm

5 μm) at 35℃. The mobile phase was methanol-0.1% formic acid (70: 30)

running at a flow rate of 0.2 mL· min-1. Mass spectrometry was performed in the multiple reaction monitoring (MRM) mode with an ESI source. Two groups of rats were orally administered with saline solution and decoction of Glycyrrhizae Radix

respectively

for consecutive 10 days. On the 11th day of administration

a single oral dose of the mixture of 6 probe drugs was given to all rats. The pharmacokinetics of probe drugs in rats was investigated

and the related pharmacokinetic parameters were statistically analyzed. Result: The HPLC-MS-MS method was validated with good sensitivity

precision

recovery and stability. It was found that Glycyrrhizae Radix could remarkably induce the enzyme activity of CYP1A2

CYP2C9

CYP2C19

CYP2D6 and CYP2E1

whereas inhibit the enzyme activity of CYP3A4. Conclusion: The established method is proved to be sensitive

reliable and simple

which is suitable for the study of Glycyrrhizae Radix or other drugs on the activity of CYP450 enzymes.