| 摘要 |
A process for the preparation of a pharmaceutical-grade anhydrous calcipotriol comprising: (a) dissolving crude calcipotriol having a water content of X % by weight in a first solvent or in a mixture of two or more first solvents, said first solvent or said mixture of two or more first solvents forming an azeotropic system with water, to obtain a solution of crude calcipotriol; (b) obtaining an intermediate calcipotriol by (i) placing said solution of crude calcipotriol under a reduced pressure and evaporating, if X is greater than or equal to 1, or (ii) crystallizing, if X is lower than 1; and (c) re-dissolving said intermediate calcipotriol in a second solvent or a mixture of two or more second solvents, said second solvent being anhydrous, and crystallizing at least once to obtain pharmaceutical-grade anhydrous calcipotriol.
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