Objective: To study pharmacokinetics and bioavailability of isochlorogenic acid A in rats with different adiminstration way. Method: A HPLC method was developed for determination of isochlorogenic acid A in rat plasma.Intravenous and intragastric doses of 32 mg ·kg-1 and 90 mg ·kg-1 were respectively administered

the concentration of isochlorogenic acid A were determined with HPLC

detection wavelength was set at 300 nm.Pharmacokinetic parameters were calculated with 3P97 software.Absolute bioavailability of isochlorogenic acid A was calculated according to AUC0-∞ and doses of isochlorogenic acid A by intravenous and intragastric administration. Result: Excellent linear relationship was obtained in the range of 0.16-110.00 mg ·L-1 with R2 of 0.998.Recoveries of isochlorogenic acid A with three concentrations (0.43

6.88

55.00 mg ·L-1) were (89.43±2.84)%

(93.16±3.95)% and (85.91±2.04)%.The intra-day RSD were 11.8%

4.0% and 4.0%.The inter-day RSD were 6.5%

5.8% and 5.8%

respectively.Metabolic processes of isochlorogenic acid A in rats fitted in with two-compartment model following intravenous and intragastric administration.Elimination half-life were (29.49±0.75) min and (44.48±0.13) min. AUC0-∞ were(355.40±32.58)

(319.91±51.00) mg ·min-1 ·L-1.Its absolute bioavailability in rats was 30.71%. Conclusion: Metabolic processes of isochlorogenic acid A in rats conform to linear dynamics with fast metabolism and short half-life.