PDLLA microparticles containing BSA: effect of formulation variables on size distribution

Worldwide, there is u currently considerable care for the development of biodegradable microspheres as systems for controlled release of medicaments. The major disadvantage of traditional administration routes of medicaments is the need for frequent repetition. Encapsulation has been proven to be an effective vehicle for the controlled delivery of various medicaments. The encapsulation efficiency and release kinetics of the medicaments have been found to be dependent upon the size of the microspheres synthesized. The aim of this study was to formulate microparticles from poly-dl-lactide (PDLLA) by modified precipitation method. Bovine serum albumin (BSA) was used as a model protein for encapsulation. The surfactant polyvinyl alcohol (PVA) was incorporated to increase encapsulation efficiency and to achieve PDLLA spheres with desired size. The main focus was to study the effect of co-solvent selection (methanol or ethanol), PVA concentration, chloroform-to-water ratio, the speed and time of homogenization and solvent removal rate on the properties of microparticles. The average size and morphology of microparticles varied substantially among these preparation conditions. An increase in stirring rate and time of homogenization and concentration of stabilizer agent were found to reduce moderately the size of microparticles. Other process parameters had limited influence on particle size