Objective:To compare the differences about general micromeritics properties of Bletillae Rhizoma powders and in vitro dissolution of total polysaccharides in this herb

in order to provide evidence for application and particle size control of Bletillae Rhizoma powder. Method:Particle sizes of Bletillae Rhizoma powders were determined by dry and wet laser particle size analyzer

bulk density

angle of repose and hygroscopicity of Bletillae Rhizoma powder were investigated and evaluated.In vitro cumulative dissolution rates of Bletillae Rhizoma powder in different dissolution medium were detected by stirring paddle method. Result:The micromeritics properies of Bletillae Rhizoma powder has changed

with the decreased of particle size

liquidity decreased and moisture weakened.The in vitro dissolution of Bletillae Rhizoma powder reduced with the particle size decreased.The cumulative dissolution of fine powder and finest powder were higher than micropowder in distilled water and simulated gastric fluid;the dissolution rate and the cumulative dissolution rate of fine powder was significantly higher than the other powders in the simulated intestinal fluid.The order of different dissolution medium for Bletillae Rhizoma powders by cumulative dissolution rates was simulated gastric fluid>distilled water>simulated intestinal fluid. Conclusion:Particle size of Bletillae Rhizoma powder has obvious effect on the dissolution of total polysaccharides and the dissolution medium has an obvious influence on the dissolution rates

which provides a reference for screening optimal particle size of Bletillae Rhizoma powder in clinical application.