(465f) The Effect of Tablet Shape On Film Coating Uniformity Using the Discrete Element Method

Film coating of pharmaceutical tablets is an important process that is conducted to help improve the tablet appearance, the stability of the active drug, taste masking, or, in the case of controlled release tablets, modify the release profile. Regardless of the rationale for applying the coating, the uniformity of the coating is an important attribute. For immediate release coatings where coatings may be applied primarily for aesthetic purposes, poor uniformity leads to reduced process efficiency and increases run times to ensure tablets with the least coating meet quality criteria while other tablets are over-coated. More serious consequences occur for functional membrane coatings that control the release of the active drug. In this case, variable coating uniformity may lead to large variability in the drug release rates.

In this work, the discrete element method (DEM) is used to computationally model the dynamics of tablet motion in a film coating pan. The number and duration of appearances in a fictitious spray zone are used to predict the coating uniformity under those conditions. A key variable explored in this work is the shape of the tablets, where different tablet shapes are approximated using the ?glued spheres? technique. The results show that tablet shape does affect the typical tablet orientation in the spray zone, and thus, the intra-tablet coating uniformity. Finally, the effect of various process conditions such as pan rotation speed and pan loading are examined. Results show that pan speed affects the intra-tablet uniformity while pan fill level seems to have a negligible effect. These results demonstrate the usefulness of modeling in guiding drug product development decisions such as shape selection and process operating conditions.