Patent ID: 9018225
Filing Date: 2015-04-28
Classification: A61K,C07D

Abstract:
1. A method for the manufacture of a composition comprising mixed crystalline polymorphs rifaximin α and rifaximin β, comprising: (a) dissolving rifaximin in a water-soluble organic solvent and warming the organic solvent to reflux; then, when the rifaximin is completely dissolved in the organic solvent to provide a solution of rifaximin in the organic solvent, (b) adding water to the solution to provide a second solution of rifaximin in a mixed solvent, the mixed solvent having an organic solvent to water ratio of about 5:5 to about 9:1 (v/v), to provide the second solution of rifaximin in the mixed solvent; then, (c) cooling the second solution to a temperature of 25-50° C., and stirring at the temperature of 25-50° C. until crystallization takes place, then (d) cooling the solution to about 0° C. with stirring, then, (e) recovering the crystallized material, then (f) drying the crystallized material to a water content of between 2.5% and 5.0%; to provide the composition comprising mixed crystalline polymorphs rifaximin α and rifaximin β, wherein the composition comprising mixed crystalline polymorphs rifaximin α and rifaximin β contains about 3% up to about 12% (w/w) of the rifaximin β crystalline polymorph in mixture with a remaining percentage of the rifaximin α crystalline polymorph.