Leiterman R V, Mulski M J, Connors K A
School of Pharmacy, University of Wisconsin, Madison 53706, USA.
J Pharm Sci. 1995 Nov;84(11):1272-5. doi: 10.1002/jps.2600841103.
The equilibrium solubility at 25 degrees C of alpha-cyclodextrin was measured in several binary aqueous-organic solvent mixtures, the organic cosolvents being methanol, 2-propanol, ethylene glycol, and acetone. Solubility maxima were observed as the solvent composition was varied from pure water to pure cosolvent. The maximum in methanol systems was hardly detectable, but it was very pronounced in 2-propanol and acetone, and two maxima were seen in the ethylene glycol system. Karl Fischer analysis of the solid phase isolated from 2-propanol/water equilibrium systems showed that alpha-cyclodextrin hexahydrate is the stable form in water, whereas a solid phase containing three water molecules per molecule of alpha-cyclodextrin is the stable form in the presence of 2-propanol. The appearance of a solubility maximum in this system, and by extension presumably in the other cosolvent systems, is attributed to the existence of more than one stable solid phase of alpha-cyclodextrin.
在25摄氏度下，测定了α-环糊精在几种二元水-有机溶剂混合物中的平衡溶解度，其中有机共溶剂为甲醇、2-丙醇、乙二醇和丙酮。当溶剂组成从纯水变化到纯共溶剂时，观察到溶解度最大值。甲醇体系中的最大值几乎无法检测到，但在2-丙醇和丙酮体系中非常明显，而在乙二醇体系中则出现了两个最大值。对从2-丙醇/水平衡体系中分离出的固相进行卡尔费休分析表明，α-环糊精六水合物是在水中的稳定形式，而在2-丙醇存在下，每分子α-环糊精含有三个水分子的固相是稳定形式。该体系中出现溶解度最大值，并且据推测其他共溶剂体系中也会出现，这归因于α-环糊精存在不止一种稳定的固相。
