Objective: To select the best formula and technology for the preparation of salvianic acid A sodium-poly(lactide-glycolic acid)(PLGA) sustained release microspheres and to discuss its pharmaceutical properties. Method: W/O/O emulsified solvent evaporation method was used to prepare the microspheres

taking drug loading

encapsulation efficiency and yield as indexes

single factor tests were used to optimize formulation

and its in vitro release was investigated.Laser particle size analyzer

scanning electron microscopy and X-ray diffraction (XRD) were used to characterise the microspheres. Result: Optimum formulation was determined

volume of internal phase was 300 μL

concentration of PLGA50/50 COOH was 125 g·L-1

the proportion of methylene chloride and acetone was 3:7

the volume of liquid paraffin was 200 mL as external oil phase

concentration of span80 was 0.25%

stirring speed was 1 400 r·min-1

stirring time was 4 h

volume of n-hexane was 6 mL.Drug loading

encapsulation efficiency and yield were (20.71±1.42)%

(63.27±1.70)% and (99.10±0.83)%

respectively.Cumulative release in vitro of 98% required 120 h.Mean particle diameter was (71.72±1.71) μm.Surfaces of salvianic acid A sodium-PLGA sustained release microspheres were smooth and spherical with honeycomb-like inner structure.XRD indicated that some drug may dispersed as crystals in carrier materials. Conclusion: Salvianic acid A sodium-PLGA sustained release microspheres can be prepared by W/O/O emulsified solvent evaporation method.This optimized process is simple and reasonable

which is base for further research of salvianic acid A sodium preparation.