Quality‐by‐Design (QbD): An Integrated Process Analytical Technology (PAT) Approach for Real‐Time Monitoring and Mapping the State of a Pharmaceutical Coprecipitation Process

In this work, an integrated PAT approach was developed for monitoring a pharmaceutical (naproxen) and a polymer (eudragit) coprecipitation process: real‐time in‐line near‐infrared (NIR) absorbance monitoring, real‐time on‐line turbidity monitoring, and in situ crystal size monitoring. The data and information obtained through these three monitoring techniques confirmed the observation of the onsets of three distinct stages: incubation, nucleation, and crystal growth. The process trajectory constructed based on results of applying principal component analysis (PCA) to either process NIR spectra data or process turbidity profile, clearly demonstrated that various distinguishable process events, including incubation, nucleation, and crystal growth, could be accurately tracked and differentiated. These findings were further supported by process knowledge and information, such as process design, process sequence, thermodynamic and mass‐transfer analysis. Therefore, this work provides a case study that illustrated a rational approach to develop a science‐based and knowledge‐based process monitoring strategy, which is essential for establishing both a suitable process control strategy and an operational process space for a pharmaceutical unit operation. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1516-1534, 2010