Abstract
Edge chipping of film-coated tablets is a persistent quality challenge in pharmaceutical manufacturing, particularly during scale-up, and can have significant economic consequences due to sorting and rejection. Although edge chipping is often attributed to process-induced stresses during coating (e.g. tablet-tablet or tablet-equipment impacts), the contribution of the mechanical properties of the coating itself remains insufficiently quantified. This study formulated three hypotheses and tested them regarding coating properties, measured directly on intact coated biconvex tablets, and evaluated their relationship to edge-chipping susceptibility. An established drop test was employed as a surrogate for chipping tendencies occurring during the coating process. The three coating properties evaluated were: (i) adhesion strength to the core, (ii) apparent indentation hardness, and (iii) apparent indentation brittleness, enabled by three newly introduced on-tablet experiments. While adhesion strength and hardness showed no direct evidence of influencing edge chipping, apparent indentation brittleness correlated strongly with chipping behavior. These results indicate coating brittleness as a key factor for relative chipping risk and motivate future integration with process force data and DEM-based simulations toward absolute predictions.