Wu X Y, Zhou Y
Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada M5S 2S2.
J Pharm Sci. 1999 Oct;88(10):1050-7. doi: 10.1021/js9804361.
This paper presents systematic analyses by the finite element method of release kinetics of a dispersed solute from various matrixes (i.e. , slab, sphere, cylinder, and convex tablet), with or without boundary-layer resistance, into a finite or an infinite external volume. In the case of sink conditions, the numerical results agree well with the existing analytical solutions. For the problems of solute release into a finite external volume, where the analytical solutions are not available, this work has provided numerical solutions of the differential equations describing the release kinetics, moving boundaries, and concentration profiles. This work has also revealed the dependence of release kinetics on the initial solute loading, the external volume, and the boundary-layer thickness. The method presented here can describe the entire process of diffusional release before and after the dispersed solute has been dissolved without the pseudo steady-state assumption and it is applicable to both small and large ratio of initial solute loading to the solute solubility in the matrix.
本文采用有限元方法，对各种基质（即平板、球体、圆柱体和凸片）中分散溶质在有无边界层阻力的情况下，向有限或无限外部体积释放的动力学进行了系统分析。在漏槽条件下，数值结果与现有的解析解吻合良好。对于溶质释放到有限外部体积的问题，由于没有解析解，本文给出了描述释放动力学、移动边界和浓度分布的微分方程的数值解。这项工作还揭示了释放动力学对初始溶质负载量、外部体积和边界层厚度的依赖性。本文提出的方法无需伪稳态假设就能描述分散溶质溶解前后扩散释放的整个过程，并且适用于初始溶质负载量与溶质在基质中溶解度之比无论是大还是小的情况。
