Objective      To establish a reverse phase HPLC (RP-HPLC) method for the determination of honokiol in rat plasma and its pharmacokinetics study.       Methods        Liquid-liquid extraction with ethyl acetate was used for plasma sample treatment and evodiamine was chosen as an internal standard. The study was performed on Lichrospher C

18

column with the mobile phase of methanol-water (80∶20

V/V) at a flow rate of 1 mL/min. The eluent was detected at wavelength of 292 nm.       Results        The results of chromatographic method showed a good specificity between analytes and matrix

and the retention time of honokiol and internal standard was 5.1 min

and 4.1 min

respectively. It showed good linearity over a range of 0.035 5 to 9.090 9  g/mL(r=0.999 6). The lower limit of quantitation (LLOQ) was 20 ng/mL. The mean extraction and method recovery rates were 106.87% and 104.44%

respectively

while inter-day and intra-day precision RSDs were all less than 8.02%.       Conclusion       The reverse phase HPLC method for honokiol determination in rat plasma is established using evodiamine as the internal standard. The developed method is fast

sensitive and accurate for determination and pharmacokinetic study of honokiol in rat plasma.