To obtain the subject compound excellent in storage stability, easy in handleability, and useful as a medicine for treating or preventing diseases caused by the abnormal absorption, transport or metabolism of calcium.
This vitamin D derivative of crystal form is represented by formula I. The derivative can be obtained by applying a crystallization treatment to a vitamin D derivative of amorphous form represented by formula II in an organic solvent containing water. For example, 10mg of the vitamin D derivative of amorphous form represented by formula II is dissolved in 0.2ml of diethyl ether, and the obtained solution is mixed with 1.35ml of toluene and subsequently stirred, until giving a homogeneous solution. The homogeneous solution is concentrated under vacuum, until being reduced to a half volume of the solution, mixed with three drops (approximately 100mg) of purified water and further stirred at room temperature for ≥15hr. The treated solution is cooled to approximately 5°C, and the deposited crystals are filtered off to obtain 7mg of the vitamin D derivative or crystal form.
UTA TOMOKO
NAKAMURA TORU
