(108f) Investigation of a Tablet Coating Process Using a Multi-Model Simulation Approach

Spray coating is a frequently used process step in the pharmaceutical industry, benefits range from the control of the release of the active pharmaceutical ingredient (API) of a tablet to the masking of the taste of the API. One of the most common processes is drum coating, where the particles are placed in a rotating drum, and the coating liquid is sprayed onto the moving particle bed. A central quality attribute is the uniformity of the coating layer, as the coating usually has critical functional properties. Besides experimental work [1], numerical simulations have become an extremely important tool in process design.

In this work, we present an innovative approach to numerically analyze, understand and optimize important steps of the pharmaceutical tablet coating process. Coater performance depends on a range of very different parameters. Therefore, to find critical process parameters and determine their effect on quality, it is necessary to combine advanced numerical techniques on different scales. A central point is the application of the developed methods to industry-scale processes.

For example, for the simulation of the tablet bed mixing the Discrete Element Method (DEM) is used, while detailed numerical analysis of the interaction between spray droplets and tablet surface is done with advanced multiphase Computational Fluid Dynamics (CFD ) methods [2]. On a larger scale, CFD can be adapted to investigate coater internal flow in terms of drying air and liquid spray movement. The results are used to optimize attributes like particles residence time, film formation or spray drying. Summarizing, the presented combination of simulation tools provide a deeper understanding of the different aspects of a coating process. The gained knowledge helps to go from trial-and-error based decisions to a Quality-by-Design approach.

[1] Dubey, A., Portillo, P.M., Muzzio, F.J., 2008. Study of Tablet Coating Thickness Uniformity Using LIBS, DEM and Compartment Modeling. 2008 AIChE Annual Meeting.

[2] Suzzi, D., Radl, S., Khinast, J.G., 2009. Local Analysis of the Tablet Coating Process: Impact of Operation Conditions on Film Quality. Submitted to Chem. Eng. Sci.