(749b) Development of Framework for Undesired Agglomeration in an Agitated Filter Drying Process

The occurrence of undesired agglomeration during an agitated filter drying process has been a long term issue in the production of pharmaceutical products. Formation of hard lumps, product degradation, extended drying times and downstream processing issues are common problems caused by unwanted agglomeration. Previous studies have demonstrated that the prevention of agglomerate formation is possible via various mitigation methods including initial moisture content reduction, optimization of filter dryer operations (e.g. temperature, pressure, speed etc.), minimization of headspace condensation and changing the filter cake wash solvent composition. While previous workers had demonstrated the effectiveness of these methods, highly cohesive pharmaceutical compounds are still likely to undergo severe agglomeration. The only options to eliminate the agglomeration phenomenon are improved crystallization protocol or granulation of powder. Reviewing our own work and previous studies by other authors suggests that each solution is not universal but is specific to certain powder-solvent combination. This work proposes a framework summarizing the formation of undesired agglomerates, incorporating several key mechanisms identified by previous workers together with new results based on our own studies. While this work may not entirely cover the potential agglomeration causes of all powders available in the pharmaceutical industry, it is understood that the framework will serve as a useful guideline in troubleshooting the formation of undesired lumps during an agitated filter drying process.