Process Validation

The three stages

The FDA's 2011 guidance replaced "three batches and you are done" with a lifecycle:

Stage 1 — Process Design. Build understanding. Development and scale-up work define what the process is and which parameters matter. This is where Quality by Design does its work; the output is a control strategy, not a batch count.

Stage 2 — Process Qualification. Confirm the designed process performs at commercial scale. Covers facility and equipment qualification plus Process Performance Qualification batches. The number of PPQ batches must be justified by risk and variability — three remains common, but as a conclusion rather than a rule.

Stage 3 — Continued Process Verification. Ongoing assurance that the process stays in control during routine production, using statistical monitoring of parameters and attributes. This stage never ends.

What changed, and why it matters

The old model treated validation as a gate: pass three batches, declare the process validated, move on. The lifecycle model treats it as a claim that must keep being true. A process that drifts two years after approval was never validated in the sense the guidance means.

Stage 3 is where most organisations are weakest, because it demands sustained statistical attention to processes that appear to be working. It is also where problems surface first — trends in yield, in-process results or deviation frequency precede batch failures, usually by a long way.

IQ / OQ / PQ

The equipment-level qualifications sit inside Stage 2:

• IQ — Installation Qualification: installed as specified
• OQ — Operational Qualification: operates across its intended range
• PQ — Performance Qualification: performs for the specific product and process

They qualify equipment and systems. Process validation qualifies the process running on them. Conflating the two is a common and expensive scoping error.