Patent ID: RE41157

Claim:
In a solvent extraction process for preparing microspheres of an antigen containing biodegradable poly(DL-lactide-co-glycolide), the improvement comprising: preparing a lyophilized antigen-sucrose matrix; adding acetonitrile solvent to the antigen-sucrose matrix to form a solution; preparing a solution of a biodegradable poly (DL-lactide-co-glycolide) polymer by adding acetonitrile solvent to the polymer; adding the biodegradable poly (DL-lactide-co-glycolide) polymer acetonitrile solution to the antigen-sucrose acetonitrile solution; adding an oil to the poly (DL-lactide-co-glycolide) polymer-sucrose-antigen solution to form an emulsion having a controlled viscosity, that corresponds to a predetermined average particle size of distributions of microspheres of poly (DL-lactide-co-glycolide) biodegradable polymers of from about 0.5 to about 7.0 micrometers; centrifuging the emulsion of controlled viscosity and removing a supernatant to obtain microspheres of the predetermined range of particle size distributions.