High-potency active pharmaceutical ingredients (HPAPIs) impose strict containment requirements that intensify during scale-up. When carrying out solid-liquid separation with HPAPIs, filtration and drying are containment risks as both can involve phase transitions, material exposure, and mechanical disturbance of the cake. At laboratory scale, these constraints are manageable, but at production scale they demand engineered solutions to maintain containment and ensure consistent performance. Safe scale-up depends on converting filtration and drying into closed, continuous operations that eliminate handling and ensure control throughout.
Phase 1: Benchtop Filtration and Drying with GFD®Lab
In early-stage development, filtration and drying are typically performed using Büchner funnels and laboratory tray dryers. While suitable for exploratory chemistry, these methods rely on manual handling of filter cakes, forming open exposure points that cannot be translated into HPAPI manufacturing.
To address the exposure risks associated with open filtration and drying through the Agitated Nutsche Filter Dryer (ANFD), which integrates filtration, washing, and drying within a single sealed vessel. This benchtop system replicates the function of larger-scale equipment under fully contained conditions, keeping development data relevant at larger scale.
By performing filtration and drying in a closed environment from the outset, the GFD®Lab enables scientists to evaluate both process chemistry and containment performance simultaneously. Cake formation, solvent displacement, and drying behaviour can all be studied under realistic conditions, including controlled vacuum levels, temperature profiles and agitation strategies, representative of larger-scale operation. This approach ensures that scale-up is built on a contained process design rather than retrofitted controls, significantly reducing the risk of exposure and loss of system integrity as batch sizes increase.
Phase 2: Bridging the Gap with GFD®Pilot
As HPAPIs move into clinical production, scale-up introduces greater demands on process performance and containment. Filtration and drying requirements increase, with greater cake thickness, higher solvent volumes, and longer drying times, and inconsistencies between development and production equipment can compromise process reliability and control.
The GFD®Pilot fliter maintains continuity between benchtop and commercial manufacturing, preserving alignment in both filtration and drying operations. Designed to mirror the mechanics of a full-scale ANFD, it ensures the process conditions developed at small scale remain valid at larger volumes. During filtration, the GFD®Pilot uses an agitator to form and maintain a uniform cake structure. When the system stabilises the cake, it improves filtration efficiency while preserving containment.
Following filtration, drying is carried out in the same sealed vessel, eliminating the need for material transfer. Controlled agitation promotes even solvent removal, ensuring consistent product quality for HPAPIs. At this stage, filtration and drying are no longer separate risks, but integrated, controlled operations carried out within a single sealed system, removing the need for intermediate handling, cleaning, physical losses and ensuring continuous containment throughout scale-up.
Phase 3: Containment at Commercial Scale with ANFD
At commercial scale, filtration and drying must function as a single, contained operation. PSL’s ANFD performs both within a sealed system, acting as the primary containment boundary for HPAPI production.
Operation begins with slurry transfer into a closed vessel, establishing containment from the outset. Filtration is then carried out under vacuum or pressure, with the agitator actively levelling the cake. This controlled cake formation is critical at scale because it:
- Prevents channel formation
- Maintains uniform resistance across the filter bed
- Ensures consistent solvent removal during both filtration and subsequent washing steps.
Rather than introducing a transfer stage, the process transitions directly within the same vessel. Drying is initiated through jacketed heating combined with vacuum, generating the driving force for solvent evaporation. The agitator continues to move the cake in a controlled manner, promoting uniform heat distribution and preventing the formation of dry zones or agglomerates that could compromise product quality or release particulates.
Removing intermediate handling keeps the HPAPI within a sealed environment from initial slurry through to final dry powder, reducing exposure potential and sustaining process control at every stage. At scale, this continuity is essential not only for containment but also for achieving consistent, repeatable drying performance across larger batch volumes.
The Final Barrier: Sealed Discharge and Cleaning
Even with fully contained filtration and drying, the final stages of discharge and cleaning must be carefully managed to preserve system integrity during scale-up. High-containment discharge valves and isolator interfaces integrate directly into the ANFD system. They ensure the dried HPAPI is transferred into downstream containers without exposure, maintaining a sealed pathway throughout.
After discharge, cleaning is carried out using integrated clean-in-place systems, which remove or neutralise residual material before the vessel is opened. This is critical for HPAPIs, where even trace contamination can pose significant risks, including cross-contamination between batches, unintended exposure to potent compounds, and compromised product purity. Automated cleaning delivers consistency, protects personnel, and supports regulatory compliance.
Together, high-containment discharge valves, isolator interfaces, and integrated cleaning systems extend containment beyond filtration and drying, providing control of the entire HPAPI process throughout discharge and cleaning operations.
Engineering Containment into HPAPI Scale-Up
In HPAPI manufacturing, containment must be engineered into filtration and drying from the beginning. Powder Systems Limited’s integrated platform, spanning GFD®Lab, GFD®Pilot, and ANFD, ensures that processes developed at the bench translate directly to manufacturing scale. The result is reduced risk, improved performance, and greater confidence in scale-up. Speak to PSL to discover how our integrated filtration and drying systems can support your HPAPI manufacturing strategy.
