Patent ID: 6913767

Claim:
A composition comprising a homogeneous population of polylactide or poly (lactide-co-glycolide) (PLGA) polymer microspheres encapsulating an antigen, wherein said homogeneous population is produced from an emulsion comprising aqueous antigen and a polylactide or PLGA polymer, and (a) the polymer has a ratio of lactide to glycolide of about 100:0 to 50:50 weight percent; (b) the polymer has an inherent viscosity of about 0.1 to 1.2 dL/g; (c) the microspheres in said homogeneous population have a median diameter of about 20 to 100 μm; and (d) the microspheres in said homogeneous population have an in vitro antigen release profile characterized by three phases: a first antigen burst phase, wherein about 0.5 to 30 percent of the antigen is released from the microspheres over a period of about three days after-suspension of the microspheres in a release medium; a second slow release phase after the first phase, extending from about the fourth to at least about the thirtieth day after suspension, wherein the daily release of antigen from the microspheres is less than in the first antigen burst phase or a third antigen burst phase; and the third antigen burst phase after the second phase, wherein antigen is released from the microspheres at a rate of greater than 10 percent per week, during a period of from about seven to about 30 days, starting from about 30 to about 180 days after suspension.