Abstract:Objective: To develop an HPLC method for determination of the plasma concentration of aristolochic acid Ⅰ (AAⅠ) and aristolochic acidⅡ (AAⅡ) and study their pharmacokinetics in rats. Method: The plasma samples were extracted with acetonitrile. The analysis involved a C18 column as stationary phase and methanol, water and acetic acid as mobile phase. The flow rate was 1.0 mL·min-1, the UV detection wavelength was 315 nm. After a single intravenous dose of 5 mg·kg-1 AA in rats, the pharmacokinetic parameters were estimated. Result: The calibration curve of AAⅠ was linear over the range from 0.056 mg·L-1 to 56.3 mg·L-1 with a correlation coefficient of 0.999 7. The mean recovery rate was 88.7%. The RSD of within-day and between-day were all less than 8%. And the calibration curve of AAⅡ was linear over the range from 0.192 mg·L-1 to 11.52 mg·L-1 with a correlation coefficient of 0.998 9. The mean recovery was 85.8%. The RSD of within-day was less than 3% and between-day was less than 10%. The main pharmacokinetic parameters were estimated to be as follows: CL=(0.010±0.003) L·min-1·kg-1, t1/2α=(8.2±1.7) min, t1/2β=(79.6±28.5) min for AAⅠ; CL=(0.003±0.001) L·min-1·kg-1, t1/2α=(56.7±38.1) min, t1/2β=(209.3±37.9) min for AAⅡ. Conclusion: The established HPLC method is simple and sensitive to determine the concentration of AAⅠ, AAⅡ and the metabolite of AAⅠ in rat plasma. From the result of animal‘s test, we can find that AAⅠ was quickly eliminated from plasma, the elimination of AAⅡ and Aristololactam-the metabolite of AAⅠ- were slower than that of AAⅠ.