Details for Patent: 7,524,530

Title:	Residual solvent extraction method and microparticles produced thereby
Abstract:	Methods for preparing microparticles having reduced residual solvent levels. Microparticles are contacted with a non-aqueous washing system to reduce the level of residual solvent in the microparticles. Preferred non-aqueous washing systems include 100% ethanol and a blend of ethanol and heptane. A solvent blend of a hardening solvent and a washing solvent can be used to harden and wash microparticles in a single step, thereby eliminating the need for a post-hardening wash step.
Inventor(s):	Rickey; Michael E. (Loveland, OH), Ramstack; J. Michael (Lunenburg, MA), Kumar; Rajesh (Marlborough, MA)
Assignee:	Alkermes, Inc. (Cambridge, MA)
Filing Date:	Apr 19, 2007
Application Number:	11/785,638
Claims:	1. A method for preparing microparticles, comprising: combining a peptide solution and a polymer solution to form an emulsion, wherein the peptide solution comprises sucrose and exendin or an exendin analog, and the polymer solution comprises a biodegradable, biocompatible polymer dissolved in a halogenated solvent; combining the emulsion with a coacervating agent that is free from solvents for the polymer to form a combined phase; extracting the halogenated solvent from the combined phase with an extraction medium of a 9:1 ratio of heptane to ethanol, whereby microparticles precipitate out of the extraction medium; and rinsing the microparticles with 100% heptane to thereby reduce the level of residual halogenated solvent. 2. The method of claim 1, wherein the coacervating agent is silicone oil. 3. The method of claim 1, wherein the coacervating agent is dimethicone. 4. The method of claim 1, wherein the polymer is selected from the group consisting of poly(glycolic acid), poly(d,l-lactic acid), poly(l-lactic acid), and copolymers of the foregoing. 5. The method of claim 4, wherein the polymer is poly (d,l-lactic-co-glycolic acid). 6. The method of claim 1, wherein the rinsing step is carried out until the level of residual halogenated solvent in the microparticles is less than about 0.06% by weight. 7. The method of claim 1, further comprising after said rinsing step: final drying of the microparticles. 8. The method of claim 1, wherein the step of combining the peptide solution and the polymer solution is carried out using a static mixer. 9. A method for preparing microparticles, comprising: combining a peptide solution and a polymer solution to form an emulsion, wherein the peptide solution comprises sucrose and exendin or an exendin analog, and the polymer solution comprises a 50:50 poly(d,l-lactic-co-glycolic acid) polymer dissolved in methylene chloride; combining the emulsion with silicone oil to form a combined phase; extracting the methylene chloride from the combined phase with an extraction medium of a 9:1 ratio of heptane to ethanol, whereby microparticles precipitate out of the extraction medium; and rinsing the microparticles with 100% heptane to thereby reduce the level of methylene chloride. 10. The method of claim 9, wherein the rinsing step is carried out until the level of residual methylene chloride in the microparticles is less than about 0.06% by weight. 11. The method of claim 9, further comprising after said rinsing step: final drying of the microparticles. 12. The method of claim 9, wherein the step of combining the peptide solution and the polymer solution is carried out using a static mixer.