Paclitaxel-loaded poly(lactic-co-glycolic acid) microspheres: preparation and in vitro evaluation

Poly(lactic-co-glycolic acid) (PLGA) microspheres containing paclitaxel were prepared by an oil-in-water (o/w) emulsification solvent evaporation method. Box Benhken experimental design was used for studying the parameters that influence the microsphere characteristics and for calculating the optimal formulation. The resulting microspheres were characterized regarding their physicochemical properties, drug content and in vitro drug release. The stirring rate had the greatest influence on particle size and particle size distribution. PLGA and polyvinyl alcohol concentrations had an important influence on drug loading: drug loading increased linearly with PLGA concentration and decreased linearly with PVA concentration. The differential scanning calorimetry proved that there are interactions between paclitaxel and polymer. The release behavior of paclitaxel from the polymer matrix exhibited a biphasic pattern characterized by a slow initial release during the first 26 days (less than 10% paclitaxel), followed by a faster and uniform release (the accumulative amount of paclitaxel released in 92 days was between 17 and 44%).