Newman Ann W, Reutzel-Edens Susan M, Zografi George
SSCI, Inc., West Lafayette, IN, USA.
J Pharm Sci. 2008 Mar;97(3):1047-59. doi: 10.1002/jps.21033.
The amount of water vapor taken up by an active pharmaceutical ingredient (API) as a function of relative humidity is routinely evaluated to characterize and monitor its "hygroscopicity" throughout the drug development process. In this minireview we address the necessity of going beyond the measurement of water vapor sorption isotherms to establish the various mechanisms by which solids interact with water and the important role played by the crystalline or amorphous form of the solid. Practical approaches for choosing experimental conditions under which water vapor sorption should be measured, including the pre-treatment of samples and the time allowed to reach an equilibrium state are presented. With the assistance of a flowchart, we provide a basis for the systematic examination of samples to establish the likely mechanisms of sorption and the indicators pointing toward future problems with physical and chemical instabilities. Finally, we present strategies for managing materials that might be susceptible to the detrimental effects of water vapor sorption.
在整个药物研发过程中，通常会评估活性药物成分（API）吸收的水蒸气量与相对湿度的关系，以表征和监测其“吸湿性”。在本微型综述中，我们探讨了超越水蒸气吸附等温线测量的必要性，以确定固体与水相互作用的各种机制以及固体的晶型或无定形形式所起的重要作用。介绍了选择测量水蒸气吸附的实验条件的实用方法，包括样品的预处理和达到平衡状态所需的时间。借助流程图，我们为系统检查样品提供了基础，以确定可能的吸附机制以及指向未来物理和化学稳定性问题的指标。最后，我们提出了管理可能易受水蒸气吸附不利影响的材料的策略。
