Objective: To optimize preparation process of ellagic acid microspheres and investigate its in vitro release mechanism for pharmacokinetic. Method: HPLC was employed to determine the content of ellagic acid with mobile phase of acetonitrile-0.1% phosphoric acid water (23:77) and detection wavelength at 254 nm.Taking release as index

orthogonal test was adopted to optimize formulation process with contents of sodium alginate

chitosan

calcium chloride and mass ratio of sodium alginate-drug as factors

zero-order kinetics equation

first order kinetics equation and Higuchi equation were taken to fit in vitro release of ellagic acid microspheres. Result: Optimum formulation was as following:sodium alginate to ellagic acid of 3:1

sodium alginate of 2%

chitosan of 0.1%

calcium chloride of 2%.Realease of ellagic acid microspheres was 80.14% within 48 h

its in vitro release fitted Higuchi equation of Q=0.131t1/2-0.046 9(r=0.966 4). Conclusion: This optimized process is stable

practicable and repeatable.Ellagic acid microspheres show sustained release performance.