Details for Patent: 8,187,672

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. (Morrow, OH), Ramstack; J. Michael (Lunenburg, MA), Kumar; Rajesh (Marlborough, MA)
Assignee:	Alkermes Pharma Ireland Limited (Dublin, IE)
Filing Date:	Dec 14, 2010
Application Number:	12/967,757
Claims:	1. A method for preparing microparticles, comprising: preparing a first phase comprising an active agent; a biodegradable, biocompatible polymer; and a solvent; preparing a continuous second phase with which the first phase is substantially immiscible; combining the first phase and the second phase to form an emulsion; extracting the solvent from the emulsion with an extraction medium, to form microparticles containing the active agent; and washing the microparticles with a non-aqueous washing system comprising ethanol to thereby reduce the level of residual solvent. 2. The method of claim 1, wherein the active agent is selected from risperidone, 9-hydroxyrisperidone, and pharmaceutically acceptable salts of the foregoing. 3. The method of claim 1, wherein the polymer is selected from poly(glycolic acid), poly(d,l-lactic acid), poly(l-lactic acid), and copolymers of the foregoing. 4. The method of claim 3, wherein the polymer is poly(d,l-lactic-co-glycolic acid). 5. The method of claim 1, wherein the solvent comprises a blend of ethyl acetate and benzyl alcohol. 6. The method of claim 1, wherein the extraction medium comprises ethyl acetate. 7. The method of claim 1, wherein the non-aqueous washing system is 100% ethanol. 8. The method of claim 1, wherein the first phase comprises risperidone, poly(d,l-lactic-co-glycolic acid), and a blend of ethyl acetate and benzyl alcohol, wherein the extraction medium comprises ethyl acetate, and wherein the non-aqueous washing system is 100% ethanol. 9. The method of claim 8, wherein the second phase comprises polyvinyl alcohol and ethyl acetate. 10. The method of claim 1, further comprising: rinsing the washed microparticles with water; and final drying of the rinsed microparticles. 11. Microparticles prepared by the method of claim 1. 12. Microparticles prepared by the method of claim 9.