Ensuring tablet quality via model-based control of a continuous direct compaction process

Switching from batch to continuous pharmaceutical production offers several advantages, such as an increased productivity, a steady product quality, and decreased costs. This paper presents a control strategy for direct compaction on a continuous tablet production line consisting of two feeders, one blender, and a tablet press (TP). A data-driven, linear modeling approach is applied in order to develop a Smith predictor for active pharmaceutical ingredient concentration control and a model predictive controller responsible for the TP hopper level. Additionally, in case of severe concentration variations out-of-specification material can be discarded before it enters the TP. The effectiveness of the control concept is tested not only in simulations but also by implementing it on a real pilot plant.