ICH Q7 clause 13: Change control

Change control is the quality system that prevents uncontrolled changes from degrading product quality. The system must cover ALL types of changes — not just process changes. Raw material suppliers, analytical methods, computer software updates, equipment modifications, label changes: all must flow through the same controlled process. The system requires documentation, review, and approval before implementation.

The change control procedure must define the process step-by-step: who can initiate a change, how it's documented, who reviews (subject matter experts), who approves (including mandatory QA approval), how impacts are assessed, how the change is implemented with controls, and how effectiveness is verified. Missing post-implementation verification is a common gap — changes must actually be evaluated for effectiveness, not just implemented and forgotten.

Impact assessment is the heart of change control — a thorough assessment prevents changes from unexpectedly compromising quality. Standard impact areas to assess: validation status (does the process need revalidation?), specifications (do limits need to change?), stability (does new data need to be generated?), regulatory (does this require regulatory filing updates?), other systems (does this affect cleaning validation, training, etc.?). Classification helps scale the response — simple changes get simple handling; significant changes get comprehensive review.

Classification is NOT about making some changes easier to implement — it's about matching the response to the risk. Minor changes (e.g., formatting changes, editorial SOP updates) need documentation and approval but not impact studies. Major changes (process parameter modifications, equipment changes) need impact assessment and possibly validation. Critical changes (new process steps, new equipment types, specification changes) need comprehensive assessment and likely regulatory filings.

QA approval is mandatory and cannot be delegated to production or R&D. The QA reviewer must be trained, independent, and has authority to reject changes. QA approval signifies that: (1) the impact assessment is adequate, (2) supporting data (if required) is sufficient, (3) implementation plan is appropriate, and (4) the change does not compromise quality. Electronic systems must enforce QA as a required approver for all GMP changes.

Significant changes can invalidate prior validation. The required response depends on the change magnitude: minor changes may need only verification runs; moderate changes may need partial revalidation; major changes may need full revalidation of affected steps or entire process. Stability programs may need to be re-initiated for changes affecting stability. Analytical methods may need verification or revalidation. The scope must be justified based on scientific assessment.

Post-implementation evaluation closes the change control loop. The first batch after the change should be scrutinized more carefully than routine batches. Comparison to pre-change batches reveals whether the change achieved its purpose and whether any unintended consequences occurred. If problems are found, the change may need to be reversed or modified. This evaluation is critical but often overlooked.

API manufacturers supply dosage form manufacturers (drug product companies). Changes to the API process can affect the drug product — even changes that keep the API within specification. The dosage form manufacturer needs to know about significant changes so they can assess impact on their own process, stability, and regulatory filings. This is typically handled through quality agreements that specify what changes trigger notification and timeframes.