Investigation by the Taguchi Method of Key Factors in the Preparation of Microspheres Based on a Copolymer of Lactic and Glycolic Acids for Increasing Their Loading with Betamethasone Acetate

The influence of the main technological parameters on incorporation of betamethasone acetate (BA) into polylactide microspheres was studied. Key factors affecting microsphere characteristics were determined by the Taguchi method. In the experiments various process parameters for microsphere preparation were varied: polymer concentration, BA concentration, ratio of aqueous to organic phase, and stirring speed. It was established that BA concentration and polymer concentration have the greatest effect on increasing BA loading. Betamethasone acetate was quantified by high-performance liquid chromatography (HPLC). Maximum BA loading was observed at polymer and BA concentrations of 100 and 20 mg/mL, respectively, an aqueous/organic phase ratio of 50 : 1, and a stirring speed of 500 rpm. BA loading in the microspheres under the optimum conditions was 4.35% (before optimization: 1.44%). The results obtained can be used to improve methods for preparing polylactide microspheres loaded with other drug substances having similar physicochemical properties.