Preparation and properties of PLGA microspheres containing hydrophilic drugs by the SPG (shirasu porous glass) membrane emulsification technique

In the present paper, monodisperse poly (lactide-co-glycolide) (PLGA) microspheres containing the hydrophilic model drug, blue dextran (BLD), were manufactured by the solvent evaporation method and the shirasu porous glass (SPG) membrane emulsification technique. In order to prepare PLGA microspheres with a higher drug loading efficiency by the membrane emulsification technique, the test of stability and productivity of the primary emulsion (w1/o emulsion) was preliminary examined by change species or concentration of the oil-soluble surfactant and the ratio of water and organic solvent. The primary emulsion (w1/o) composed of the BLD aqueous solution and dichloromethane (DCM) dissolved PLGA was prepared with the micro homogenizer. The secondary emulsion (w1/o/w2) was prepared by the SPG membrane emulsification technique. BLD/PLGA microspheres of various micro level sizes of 2.0–10 μm prepared by variation of pore size of the using SPG membrane. The highly monodisperse BLD/PLGA microspheres were also manufactured by added polyethylene glycol (PEG) into the water phase, as reported in a previous paper. The initial release rate of the drug from such microspheres controlled than the sample manufactured without an additive.