It was 2011 when FDA published their Guidance for Industry: Process Validation: General Principles and Practices.
This document radically changed FDA interpretation of process validation.
According to the guidelines validation means “the collection and evaluation of data, from the process design stage through commercial production, which establishes scientific evidence that a process is capable of consistently delivering quality product.” It will no longer be a formalized activity that is limited in time and, typically, to three validation batches.
For most of us, the most challenging consequence of the new approach is that process validation never ends. As long as a process is in use, it is undergoing validation, either in stage 1 (development), stage 2 (qualification) or stage 3 (continued verification), and validation will continue until the process is no longer used.
Once we have fully understood the new concept of the life cycle approach to process validation, we have to recognize that some typical phrases and words that we have been using for decades are now obsolete.
Here are some examples:
- “The process was validated.”
A common statement so far, but it no longer makes sense. Reading or hearing it should make us raise an eyebrow. As validation never ends, to speak of process validation in the past tense has become as much of a fossil as the old validation concept of “three consecutive batches.”
Instead, today, we would say, “The process was qualified.” We should further consider replacing the notion of a “validated process” with the concept of “process validity.” Is the process under control? By FDA‘s definition, the collected process data and their evaluation should give us the answer..
- The beloved “validation runs”
These also belong to history. Under the new definition, every run is a validation run. Depending on the maturity of the process, the validation runs can be called development, qualification, or verification runs.
- “Revalidation” now makes no sense. We cannot redo something that never ends. We can imagine situations where a process needs to be requalified or even redeveloped; but not revalidated.
- Retrospective, concurrent, and prospective validation
What do they mean today where validation never ends? If process validation is “the collection and evaluation of data,” isn‘t process validation simultaneously concurrent (the collection of data), retrospective (the evaluation of data), and prospective (the application of inferential statistics)? Collecting data prospectively, however, is hard to imagine.
Considering that the new validation concept changes the meaning of many hitherto common terms (think of “qualification” applied to processes, where the term had typically been used for qualifying equipment), one can ask why the FDA decided to still use the term “process validation“ at all. What if they had chosen to use “process control” or “process stability” instead? Wouldn’t this wording better express what the new guidance is all about?
The difficulty may have been that process validation is not only an industrial quality assurance tool (along with keeping process control charts, and evaluations like Six Sigma, for example.)
The term also enters the domain of the application for and the approval of new drugs. To obtain marketing authorization, the applicant has to demonstrate that he is able to reliably produce commercial quantities of the new drug. The proof of the ability to manufacture is typically submitted in the form of a Process Validation package or dossier. Regulators must have decided to keep the term “process validation“ to maintain the alignment with the wording governing the application for new drugs.
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