Improving the effectiveness of the Comil as a dry-coating process: Enabling direct compaction for high drug loading formulations

Abstract

This study investigated the Comil as a dry-coating process to enhance the flowability of pharmaceutical powders. As a major novelty, the mean residence time was measured and the effect of processing conditions on the extent of flowability enhancement was evaluated. As opposed to previous work which used a “multi-pass” approach to increase residence time and to improve the effectiveness of the Comil, this study reduces the open area of the screen. This simple modification to the screen increases residence time and allowed the Comil to improve flowability of a model cohesive powder, Avicel PH 105, as effectively as the LabRAM blender which was used as a benchmarking dry-coating device. The comilling process was applied to four fine and poorly flowing APIs which were subsequently used in high drug loading (50% w/w) formulations. In comparison to conventional blending, it was shown that comilling can significantly enhance the manufacturability of the formulations.