Drug product modeling predictions for scale-up of tablet film coating—A quality by design approach

This work describes the use of two fundamental tablet film coating models in a quality by design (QbD) approach to determine the operating parameters for scale-up of Varenicline IR (Chantix®/Champix®) tablet film coating. The models were used in this study to establish an acceptable range of process parameters in a previously unqualified film coater to match the proven acceptable range (PAR) of operating conditions in the existing coaters. The established process parameters were then used to prioritize the experimental design to minimize the number of required trial runs and shift the focus to optimization rather than validation. Based on the model predictions, the following equipment set points were determined: (1) upper and lower inlet air temperatures of 75 °C and 65 °C, respectively, to maintain environmental similarity during film coating, and (2) atomization air pressure of 3.0 bar at the lower spray rate condition and 3.5 bar at the upper spray rate condition to match the coating solution droplet diameter. The recommendations were provided to the commercial site to guide the design of their scale-up trials. The results from the actual trials were compared against the corresponding model predictions to assess the validity of the guidance provided based on the two models. The use of these theoretical models provides a scientific basis for establishing new operating parameters during scale-up of the film coating process.