Patent ID: 9157166
Filing Date: 2015-10-13
Classification: A61P,C07D,C30B

Abstract:
1. A process for preparing the crystalline form A of febuxostat, comprising the following steps: a) Dissolving febuxostat in a solvent selected from the group consisting of ethyl acetate, isopropyl acetate and ethyl formiate in a proportion from 5 to 60 ml of solvent per gram of solute, at a temperature between 50° C. and boiling temperature of the solution; b) Forming the crystals by keeping the solution from step a) at a temperature between 45° C. and boiling temperature of the mixture over a period of 1-24 hours, when the solvent is ethyl acetate or isopropyl acetate; and c) Isolating the crystalline form A of febuxostat, by cooling at room temperature, from c.1.) the suspension from step b), and thereby standing over a period of 3-15 hours; or c.2.) the solution from step a), without going through step b), by stirring over a period of 3-24 hours, when the solvent is ethyl formiate; followed by filtration and drying.