Mathematical Modeling of an Aqueous Film Coating Process in a Bohle Lab-Coater, Part 1: Development

Aqueous film coating is widely used within the pharmaceutical industry to apply either protection or functional coatings on tablets. Especially for functional coatings, smooth and homogeneous films are necessary to ensure the desired functionality. Several film-coating defects can occur as a result of improper drying conditions. Primarily cratering and sticking lead to defects that might be attributed to insufficient drying conditions. If the drying conditions are excessive, blistering or pinholes in the coating film might be observed.1 In addition, insufficient drying conditions can lead to a decomposition of the active substance. This decomposition is usually a result of high temperature or high water content in the core. These undesirable effects display the necessity of optimizing the drying process. In different studies, the influence of inlet air temperature and humidity, air-flow rate, and spray rate on the quality of the product were investigated.

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