Visual imaging as a process analytical technology tool for the understanding and on-line monitoring of pellet coating process

The goal of this study was to validate visual imaging as a process analytical technology (PAT) tool for the understanding and on-line monitoring of pellet coating processes. An automatic imaging system was designed for on-line, in-line or at-line fast analysis of pharmaceutical pellets. A simple yet effective tool is proposed to gain additional insight into the coating process. The method is based on shape classification of the pellets and enables better statistical analysis by including only relevant pellets. Moreover, the method enables better understanding of the coating process sub-processes and their effects on the pellet shape and size. The detection of shape changes was also exploited to estimate the undesirable effect of agglomeration. Furthermore, tracking with Kalman filter was performed in order to distinguish agglomerated pellets and pellets that randomly met in the moment of image acquisition. The presented visual imaging approach can be an effective PAT tool for coating thickness analysis and also enables alarming, controlling and end-point monitoring of the coating process.