Fickian Diffusion Modeling and Experimental Validation of Diclofenac Release From Cylindrical Matrix Tablets: Analytical and Finite Element Insights

ABSTRACT Controlled drug release systems play a crucial role in enhancing therapeutic effectiveness while reducing side effects. This study dives deep into the dynamics of drug diffusion within a cylindrical matrix, employing both analytical and numerical methods. An axisymmetric transient diffusion model, governed by Fick's second law in cylindrical coordinates, was developed to predict spatiotemporal drug concentration profiles. The analytical solution, derived using separation of variables and Bessel functions, was cross‐validated with the finite element method (FEM) simulations in COMSOL. Experimental dissolution was conducted under USP Apparatus II (paddle) conditions for diclofenac sodium tablets (75 and 100 mg) and data were fitted to the model, enabling precise determination of diffusion coefficients (8–10 × 10 − 1 1 m 2 /s). Parametric analyses showed that higher diffusion coefficients lead to faster drug depletion, while higher initial concentrations extend the release kinetics. The strong alignment between analytical predictions, numerical results, and experimental data underscores the model's robustness in describing Fickian diffusion mechanisms. This work provides a validated framework for optimizing cylindrical drug delivery systems, with implications for personalized pharmaceutical design.