DEM-DDM investigation of the intra-tablet coating uniformity for tablets with different shapes

Coating uniformity is important for the quality, safety, and efficacy of tablets in the pharmaceutical industry. Among the various research methods, discrete element method (DEM) is a powerful tool for numerically investigating the coating process in particle level, increasing the understanding of coating uniformity and improving related processes. In this study, the combination of DEM and discrete droplet method (DDM) is applied for the simulation of tablet coating process, including the intra-tablet coating uniformity of differently shaped tablets. The biconvex tablets are described by multi-super-ellipsoid approach in this study. In order to obtain the coating thickness distribution on each tablet, two particle surface-based meshing methods are proposed. The proposed intra-tablet DEM-DDM coating model is subsequently verified by the qualitative comparison with both theoretical models and experimental results from other literature. Finally, the influence of tablet shape on the intra-tablet coating uniformity is investigated, including tablets with different aspect ratios and height ratios.