PROCESS FOR PREPARATION OF A PHARMACEUTICAL GRADE CALCIPOTRIOL ANHYDROUS

摘要

A process for the preparation of a pharmaceutical grade calcipotriol anhydrous, wherein a crude calcipotriol is dissolved in one or more solvents, of which at least one forms azeotropic system with water, and then: a) in the case the water and impurities content in the substance exceeds the admissible level, solvents are azeotropically evaporated under reduced pressure, resulting in a clear anhydrous oil , or (b) in the case the water content in the substance does not exceed the admissible level, the solution is allowed to crystallize the product, (c) product obtained in step (a) or (b) is crystallized at least once from anhydrous solvent or mixture of anhydrous solvents.