PROCESS FOR PREPARING CRYSTALLINE FORM A OF LANSOPRAZOLE

摘要

A method for preparing crystalline form A of lasnoprazole is provided to mass-produce the crystalline form A of lasnoprazole with high purity without a separate converting step from an ethanol solvent by adjusting the temperature and agitation time required for crystallization. The method comprises the steps of: (a) after dissolving 1 part by weight of lansoprazole obtained by oxidizing 2-([3-methyl-4-(2,2,2-trifluoroethoxy)-2-pyridinyl]-methyl)thio-1H-benzimidazole in 1-50 parts by weight of ethanol, adding water thereto; (b) agitating the product obtained from the step(a) at a temperature of 15-40 deg.C for 0.5-4 hours; and (c) filtering and drying the product obtained from the step(b). Before adding the water, the color of the solution is removed by using charcoal and Na2S2O4.