Preparation and Characterization of Estradiol Valerate Microspheres Using Biodegradable Polymers

In this study, microspheres containing estradiol valerate were prepared by solventevaporation method using poly (glycolide-co-lactide) (plga 50:50) and poly(lactide). the effect of different process variables such as polymer type, drugpolymerratio, stirring rate, volume of internal phase and temperature of externalphase on the morphology, particle size distribution, encapsulation efficiency and invitro release profile were investigated. all microspheres had spherical shape withsmooth surface. increasing the internal phase volume and decreasing the externalphase temperature resulted in smaller particles. at low drug loadings, plgamicrospheres were larger than pla ones. changing the theoretical drug loading from5 to 20% decreased the drug release rate from plga microspheres whereas the resultfor pla microspheres was the opposite.