Lean Filtration: Approaches for the Estimation of Cake Properties

The majority of active pharmaceutical ingredients (APIs) and intermediates are isolated as solid products through crystallintion, filtration, and drying. In some cases, filtration of APIs and intermediates exhibit long cycle times and may potentially become the bottleneck of the entire process train. Thus, early assessment of the cake properties is typically required to evaluate filtration performance prior to scale-up. This work presents two approaches to rapidly estimate the specific cake resistance through lab studies. Using the first approach, a first-order approximation of the specific cake resistance is estimated from data collected during a simple Buchner funnel filtration. The second approach provides a more accurate estimate from a more extensive filtration study incorporating dynamic pressure modulation (DPM, a single filtration with ascending pressures), improving the fidelity of filtration predictions. Results from several case studies demonstrate how a workflow combining these two approaches can be appropriately employed to assess the cake properties from laboratory filtrations for predictions of the pilot/manufacturing plant filtration performance.