(505f) Continuous Fluidized Bed Drying of Pharmaceutical Granulations: Prediction of the Moisture Content

Hao Chen ^a, Subham Rustagi ^a, Emily Diep ^a, Timothy A. G. Langrish^b, Benjamin J. Glasser ^a

^aDepartment of Chemical and Biochemical Engineering, Rutgers University, Piscataway, NJ, 08854

^bSchool of Chemical and Biomolecular Engineering, The University of Sydney, NSW 2006, Australia

In recent years, continuous manufacturing has been adopted in a number of pharmaceutical manufacturing processes. Traditional batch manufacturing requires long processing times and consumes a tremendous amount of materials during process development. There is the potential for continuous processing to reduce development times and processing times. Although there are no regulatory hurdles for implementing continuous manufacturing, the lack of understanding of continuous pharmaceutical unit operations has limited the integration of unit operations into continuous lines. For drying of pharmaceutical granulations, batch fluidized bed drying has been the traditional way of removing the moisture due to good mixing and gentle drying behavior. In continuous drying, there are many unanswered questions in terms of the effect of process conditions on the effluent moisture content.

In this study, experiments were conducted in a modified Glatt GPCG-2 continuous fluidized bed dryer. A twin-screw feeder was used to feed wet powder into the continuous dryer. A model for predicting the effluent moisture content was developed by combining the drying kinetics and residence time distribution (RTD) of powder in the dryer. The drying kinetics were obtained from a batch fluidized bed drying process. The RTD was characterized by carrying out a tracer response test in the continuous fluidized bed. A tank-in-series model was used to describe the RTD curves. A maximum mixedness model (MMM) was adopted for characterizing the micromixing in the continuous fluidized bed. All of the resulting information from the batch experiments (drying kinetics) and information from the flow of powder through the continuous dryer (RTD) was combined into a model to predict the effluent moisture content. The results of the model were compared to experimental results and we discuss how the operating conditions affect the resulting effluent moisture content.