| 摘要 |
<p>Little hygroscopic anhydrous mirtazapine crystals showing moisture absorption of 0.6% by weight or less when stored in the atmosphere at 25 °C at a relative humidity of 75% under atmospheric pressure for 500 hours; a process for producing anhydrous mirtazapine crystals showing moisture absorption of 0.6% by weight or less when stored in the atmosphere at 25 °C at a relative humidity of 75% under atmospheric pressure for 500 hours characterized by drying crystals of mirtazapine hydrate; crystals of mirtazapine hydrate represented by formula (I), wherein n represents an integer of from 1 to 5; and a process for producing crystals of mirtazapine hydrate characterized by crystallizing crude mirtazapine by using a water soluble polar organic solvent and water. By using this production method, stable anhydrous mirtazapine having little hygroscopicity can be produced by a convenient industrial method. The anhydrous mirtazapine crystals are favorable in the low hygroscopicity and appropriately usable as, for example, an antidepressant.</p> |
