The coating uniformity of tablets is an extremely important feature in pharmaceutical manufacturing. Many coating devices have been used, studied and analyzed using experimental as well as computational methods such as Discrete Element Modeling (DEM). This study attempts to explore compartment modeling as a faster and accurate supplement to these methods. Compartment modeling has been utilized to study mixing processes in large scale aerated and stirred reactors, and more recently to study granular mixing in continuous blenders. Here, the approach is used to examine the coating distribution within each subsection. It involves spatially discretizing the system into a number of subsections. In this study we examine two subsections one compartment represents the coating area (spray zone) whereas the other compartment is not exposed to coating. Within each subsection a number of entities exist, the ratio of entities between each subsection has been studied. Another parameter studied is the rate entities are exchanged between subsections.

This study approaches the tablet coating mixing problem from three directions – a) experimental analysis using Laser Induced Breakdown Spectroscopy (LIBS) which shows the content and thickness uniformity of tablets, b) computational analysis using DEM modeling, and c) compartment modeling. The results show good agreement when comparing residence time in the spray zone which is an indicator of the coating thickness of the tablets.