FORMULATION OF BOVINE SERUM-ALBUMIN LOADED PLGA MICROSPHERES - INFLUENCE OF THE PROCESS VARIABLES ON THE LOADING AND IN-VITRO RELEASE

Three commercially available PLGA polymers (copolymer ratio of 50/50 a nd molecular weights of 85, 87 and 15 kDa) were used to prepare micros pheres containing a model protein, bovine serum albumin, using two dif ferent processes based on the (water-in-oil)-in-water emulsion solvent evaporation technique. The influence of the formulation and processin g parameters on particle size, encapsulation efficiency and in vitro r elease profiles of bovine serum albumin was assessed. The results show ed that both the encapsulation efficiency and the protein release rate were closely dependent on the molecular mass of the coating polymer. It was found that the encapsulation efficiency increased when the mole cular weight of the polymer decreased Moreover, the burst phenomenon n oted in the release profiles of the protein was also reduced. Thus, it appears that relatively low molecular mass PLGA polymers may be appro priate for the preparation of microspheres carrying large proteins suc h as bovine serum albumin.