Statistical Modeling of the Coating Uniformity in a Wurster Coating Process

Abstract

Modeling pharmaceutical coating processes involves considering many complex phenomena. Detailed models fail to cover the whole coating duration due to the large computational expense, while the input parameters for statistical models are usually difficult to obtain. In the present work a statistical model was derived from detailed numerical simulations of a Wurster coater. The model provides the possibility to evaluate the impact of the inlet air flow rate, spray rate, coating level and solid mass fraction in the spray solution on the coating uniformity over the full process duration. It was found that the coating uniformity scales with the inverse square root of the number of cycles, which the particles undergo during the coating process. Based on the model, a strategy for the systematic optimization of the process parameters is presented.