METHOD FOR SELECTIVE CRYSTALLIZATION OF 3-PYRIDYL-1-HYDROXYETHYLIDENE-1,1-BISPHOSPHONIC ACID SODIUM AS HEMIPENTAHYDRATE OR MONOHYDRATE

摘要

PROBLEM TO BE SOLVED: To provide a method of preparing 3-pyridyl-1-hydroxyethylidene-1,1-bisphosphonic acid (risedronate) sodium hemipentahydrate or monohydrate.SOLUTION: A process for producing a hydrate comprises the steps of: (a) providing an aqueous solution of 3-pyridyl-1-hydroxyethylidene-1,1-bisphosphonic acid sodium; (b) heating the aqueous solution; (c) adding an alcohol to the aqueous solution; and (d) cooling the aqueous solution. The step (b) includes heating the aqueous solution to a temperature of 25-75°C. The step (d) includes cooling the aqueous solution at a cooling rate of 0.06 to 5°C/min. The alcohol is isopropanol.SELECTED DRAWING: None