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在二元和三元水体系冷冻干燥过程中甘露醇在玻璃化转变温度以下的结晶现象。

Crystallization of mannitol below Tg' during freeze-drying in binary and ternary aqueous systems.

作者信息

Pyne Abira, Surana Rahul, Suryanarayanan Raj

机构信息

Department of Pharmaceutics, University of Minnesota, Minneapolis 55455, USA.

出版信息

Pharm Res. 2002 Jun;19(6):901-8. doi: 10.1023/a:1016129521485.

Abstract

PURPOSE

To characterize the phase transitions in a multicomponent system during the various stages of the freeze-drying process and to evaluate the crystallization behavior below Tg' (glass transition temperature of maximally freeze-concentrated amorphous phase) in frozen aqueous solutions and during freeze-drying.

METHODS

X-ray powder diffractometry (XRD) and differential scanning calorimetry (DSC) were used to study frozen aqueous solutions of mannitol with or without trehalose. By attaching a vacuum pump to the low-temperature stage of the diffractometer, it was possible to simulate the freeze-drying process in situ in the sample chamber of the XRD. This enabled real-time monitoring of the solid state of the solutes during the process.

RESULTS

In rapidly cooled aqueous solutions containing only mannitol (10% w/w), the solute was retained amorphous. Annealing of frozen solutions or primary drying. both below Tg', resulted in crystallization of mannitol hydrate. Similar effects were observed in the presence of trehalose (2% w/w). At higher concentrations (> or =5% w/w) of this noncrystallizing sugar. annealing below Tg' led to nucleation but not crystallization. However, during primary drying, crystallization of mannitol hydrate was observed.

CONCLUSIONS

The combination of in situ XRD and DSC has given a unique insight into phase transitions during freeze-drying as a function of processing conditions and formulation variables. In the presence of trehalose, mannitol crystallization was inhibited in frozen solutions but not during primary drying.

摘要

目的

表征多组分系统在冷冻干燥过程各阶段的相变,并评估冷冻水溶液及冷冻干燥过程中低于Tg'(最大冷冻浓缩非晶相的玻璃化转变温度)时的结晶行为。

方法

采用X射线粉末衍射法(XRD)和差示扫描量热法(DSC)研究含或不含海藻糖的甘露醇冷冻水溶液。通过在衍射仪低温阶段连接真空泵,可在XRD样品室中原位模拟冷冻干燥过程。这使得能够实时监测过程中溶质的固态情况。

结果

在仅含甘露醇(10% w/w)的快速冷却水溶液中,溶质保持非晶态。冷冻溶液退火或初次干燥,均在Tg'以下,导致甘露醇水合物结晶。在存在海藻糖(2% w/w)时观察到类似效果。在这种非结晶糖的较高浓度(≥5% w/w)下,低于Tg'退火导致成核但未结晶。然而,在初次干燥期间,观察到甘露醇水合物结晶。

结论

原位XRD和DSC的结合为冷冻干燥过程中的相变提供了独特见解,该相变是加工条件和配方变量的函数。在存在海藻糖的情况下,冷冻溶液中甘露醇结晶受到抑制,但初次干燥期间未受抑制。

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