Wu Yu San, Frijlink Henderik W, van Vliet Lucas J, Stokroos Ietse, van der Voort Maarschalk Kees
Department of Pharmaceutical Technology and Biopharmacy, Groningen University Institute for Drug Exploration (GUIDE), Ant. Deusinglaan 1, 9713 AV, Groningen, The Netherlands.
Pharm Res. 2005 Aug;22(8):1399-405. doi: 10.1007/s11095-005-5280-x. Epub 2005 Aug 3.
Several phenomena in tablets indicate that an inhomogeneous pore distribution is formed during the compaction process. Examples are lamination and the capping of corners. In order to gain an understanding of the relation between structure and compact properties, analyzing the structure in a location dependent manner would be extremely useful. Our aim was to visualize and to quantitatively analyze the pore distribution in compacts.
This was done by embedding a cubic (sodium chloride) compact with polymer, allowing the compact to be cut without disrupting the structure. By doing so, it was possible to make scanning electron microscopic images from different angles at different locations in the compact. These images were made binary with a two-means cluster algorithm (Isodata) after which the porosity could be calculated. Counting the number of transitions from the pixels in the pores to the pixels in the sodium chloride particles in two perpendicular directions allows us to construct a measure for the anisotropic connectivity of the particles.
The results show an increase in porosity toward the bottom of the compact and showed a preferred orientation of the pores in the direction of compression.
The proposed method is suitable for analyzing the pore distribution quantitatively and for evaluating anisotropy.
片剂中的几种现象表明，在压制过程中会形成不均匀的孔隙分布。例如层裂和边角裂片。为了理解结构与压坯性能之间的关系，以位置依赖的方式分析结构将非常有用。我们的目的是可视化并定量分析压坯中的孔隙分布。
通过用聚合物包埋立方体形（氯化钠）压坯，使压坯在不破坏结构的情况下被切割。这样，就可以在压坯的不同位置从不同角度制作扫描电子显微镜图像。这些图像用双均值聚类算法（迭代自组织数据分析技术算法）进行二值化处理，之后可以计算孔隙率。在两个垂直方向上计算从孔隙中的像素到氯化钠颗粒中的像素的转变次数，使我们能够构建颗粒各向异性连通性的度量。
结果表明，压坯底部的孔隙率增加，且孔隙在压缩方向上呈现择优取向。
所提出的方法适用于定量分析孔隙分布和评估各向异性。
