A novel preparation method for PLGA microspheres using non-halogenated solvents

We investigated a new preparation method for microspheres based on an Oil/Water type emulsion solvent evaporation method using non-halogenated solvents. This method is based on phase separation between acetone and aqueous glycerol. For the preparation of microspheres by this method, a solution of poly(dl-lactic-co-glycolic acid) (PLGA) in acetone and aqueous glycerol containing poly(vinyl alcohol) were used as the dispersed and continuous phases in the emulsification process, respectively. Vitamin B12 was used as the model drug. The formation of PLGA microspheres was observed above 60% glycerol in the continuous phase. The yield and encapsulation efficiency of the PLGA microspheres was about 80%, which was the maximum yield obtained with 70% glycerol. The release of vitamin B12 lasted for three weeks.