What is the purpose of process performance qualification?

Why

In FDA’s lifecycle approach, process design establishes understanding, and Stage 2 qualification assesses readiness and performance using appropriately qualified utilities, equipment, trained staff and a preapproved PPQ protocol. The protocol defines sampling, criteria, statistical reasoning, deviations and responsibilities. For a biologic, selected runs might track cell-growth characteristics, key process parameters and critical quality attributes across relevant process phases.

Data should support the claim that the designed process operates under control, not merely that three convenient lots happened to meet release limits. The number of batches and sampling intensity should be scientifically justified, not treated as a universal magic number. Successful PPQ leads into continued process verification, which looks for drift and maintains process understanding throughout routine manufacture.