Process Analytical Technology (PAT) is a system for getting a right batch every time by using on-line/in-line sensors (rather than taking measurements or samples to the lab) and knowledge of the process often implemented in advanced process control (APC) algorithms.
The goal of the directive was for pharma to consistently get batches right, with less FDA oversight, less reliance on post-production quality inspection and less testing. While the right dose with the right efficacy is important, pharma has derived another major benefit from the directive-control.