Double-layered PLGA microspheres for effective controlled release of raloxifene-HCl: Preparation and characterization

Raloxifene-HCl is a selective estrogen receptor modulator (SERM) and is currently used to prevent osteoporosis in postmenopausal women. Poly (L-lactide-co-glycolide) (PLGA) has been widely used as a carrier in controlled-release delivery systems because of good biodegradability and relatively high biocompatibility. We prepared raloxifene-HCl-loaded double-layered PLGA microspheres using an oil-in-oil-in-water double-emulsion solvent evaporation method. The raloxifene-HCl-loaded double-layered PLGA microspheres were surfacecharacterized, and there cross-sectional morphology was viewed by scanning electron microscophy (SEM). The In vitro release behavior of raloxifene-HCl over 4 weeks was analyzed by HPLC. SEM observation revealed that the double-layered PLGA microspheres had smooth surfaces and obvious differences between the core and the outer - shell. The influence of preparation parameters, such as the molecular weight of PLGA and the initial drug loading ratio, was studied with respect to release of raloxifene-HCl. The results showed that release behavior could be effectively controlled by varying the preparation parameters.