Objective:Using chlorzoxazone (CZX) as the 'probe drug’

to establish a rapid and accurate method for evaluating the activities of cytochrome P4502E1(CYP2E1) by the high-performance liquid chromatography-UV detection. Method: In vivo study: 20 mg·kg-1 of CZX was given to the rats via the tail vein. Blood samples were collected at designed time points post dose and plasma samples were obtained. CZX and 6-hydroxy chlorzoxazone (6-OHCZX) were determined by an HPLC method. In vitro study:After incubation

the formation rate of 6-OHCZX was used to evaluate the function of CYP2E1.The analysis was performed on the Agilent Extend-C18 column (4.6 mm×100 mm

5 μm)

with a mobile phase consisting of acetonitrile-0.6% acetic acid in water at a flow rate of 1.0 mL·min-1. Phenacetin was used as the internal standard. The detection wavelength was 290 nm

and column temperature was set at 30 ℃. Result: In vivo and in vitro experiments revealed that the methods had good linear ranges and their intra-and inter-day relative standard deviations

relative recoveries

stabilities met the requirement of biological estimation. Conclusion: Other endogenous substances in the plasma and incubation system did not interfere with the determination. The method is rapid

stable and highly sensitive. It is suitable for determination of CZX and its metabolites 6-OHCZX and can be used for in vivo and in vitro evaluation of CYP2E1 activitise and research of enzyme kinetics.