Patent ID: 8628701

Claim:
A method of preparing micro-capsules comprising: a. emulsifying a first aqueous solution comprising buprenorphrine into a polymer solution comprising a polymer and a polymer solvent to create a water in oil emulsion, wherein said polymer comprises poly(lactide-co-glycolide acid); b. providing a second aqueous solution wherein the pH of said second aqueous solution is adjusted to between about 7.4 and about 8.0 with phosphate, Tris, or borate buffer; c. emulsifying said water in oil emulsion in said second aqueous solution to create a water in oil in water emulsion wherein the pH of the water in oil in water emulsion is maintained between about 7.4 and about 8.0 throughout the emulsifying process; d. precipitating micro-capsules by evaporating said polymer solvent from said water in oil in water emulsion; wherein the micro-capsules have an encapsulation efficiency of at least about seventy percent, and a steady release rate over at least one month.