Objective:To prepare uniform-sized silybin loaded poly (lactic-co-glycolic acid) (PLGA) microspheres and optimize its preparation technology. Method: Silybin PLGA microspheres was prepared by premix membrane emulsification-solvent extraction/evaporation method

with the average particle size and span as indexes

oil phase solvent

membrane pore size

membrane pressure and volume ratio of oil-water phase were investigated by single factor test

influence of pharmaceutical-accessories ratio

the mass fraction of PVA and volume ratio of oil-water phase on preparation technology was investigated by orthogonal test;The mean particle size

particle size distribution

drug loading

entrapment efficiency

morphology and other physical-chemical properties were evaluated. Result: Pore size of SPG membrane was 2.8 μm

membrane pressure was 1.0 MPa

centrifuged time of 20 min

physiological saline as hardening liquid;Optimum preparation technology of silybin PLGA microspheres was as following:pharmaceutical-accessories ratio of 1:4

the mass fraction of PVA of 3%

volume ratio of oil-water phase of 1:19.Prepared microspheres were round with smooth surface

the mean diameter was (2.634±0.35) μm

span was (13.326±3.06)

drug loading was (14.84±0.76)% and entrapment efficiency was (56.16±3.77)%. Conclusion: Premix membrane emulsification method could be used to prepare silybin PLGA microspheres

which was an insoluble component from Chinese meteria medica

and particle size of prepared silybin PLGA microspheres was uniform and controllable.