Mechanical and Aerospace Engineering Department, University of Texas at Arlington, Arlington, TX, USA.
Division of Biomedical Engineering, University of Glasgow, UK; Glasgow Computational Engineering Centre, University of Glasgow, Glasgow, UK.
Int J Pharm. 2022 Mar 25;616:121442. doi: 10.1016/j.ijpharm.2021.121442. Epub 2022 Jan 4.
Controlled release of a drug contained in a spherical polymer capsule is of significant interest in many fields of medicine. There is growing interest in tailoring the erosion properties of the drug to help control and optimize the drug release process. Theoretical understanding of the nature of drug release from a bioerodible capsule is, therefore, important for designing effective drug delivery systems. While drug release from a fixed-radius capsule is relatively easier to model, the shrinking nature of a bioerodible capsule due to surface erosion presents several difficulties in theoretical modeling. This work presents a closed-form solution for the drug concentration distribution and drug delivery characteristics from a spherical capsule undergoing linear surface erosion. This problem is solved by a transformation that converts the moving boundary problem into a fixed boundary problem. For uniform initial drug distribution, the solution is shown to depend on a single non-dimensional parameter. The theoretical model is used to develop an understanding of the impact of varying the drug diffusion coefficient and rate of erosion on drug delivery characteristics. It is found that, in general, the nature of drug release in a bioerodible sphere is determined by a delicate balance between two simultaneously occurring processes - erosion and diffusion. This work improves the theoretical understanding of diffusion in drug delivery systems by accounting for the practical erosion phenomena, and may contribute towards the design and optimization of drug delivery systems.
球形聚合物胶囊中药物的控制释放在许多医学领域都具有重要意义。人们越来越感兴趣的是调整药物的侵蚀特性，以帮助控制和优化药物释放过程。因此，从理论上理解生物可蚀胶囊中药物释放的性质对于设计有效的药物输送系统非常重要。虽然从固定半径胶囊中释放药物的模型相对简单，但由于表面侵蚀导致生物可蚀胶囊的收缩性质在理论建模方面存在一些困难。本工作提出了一种用于线性表面侵蚀球形胶囊中药物浓度分布和药物输送特性的封闭解。通过一种将移动边界问题转化为固定边界问题的变换来解决这个问题。对于均匀的初始药物分布，该解仅取决于一个无量纲参数。该理论模型用于了解改变药物扩散系数和侵蚀速率对药物输送特性的影响。结果表明，一般来说，生物可蚀球体中药物释放的性质取决于两个同时发生的过程——侵蚀和扩散之间的微妙平衡。本工作通过考虑实际的侵蚀现象，提高了药物输送系统中扩散的理论理解，并可能有助于药物输送系统的设计和优化。
