Analytical Method Validation: Expert Panel Discussion on ICH Q2 Revision 2

This summary accompanies a recent expert forum discussion organised by BioQC, and we appreciate the panellists’ time and expertise.

This expert panel discussion explores the evolution of analytical method validation under ICH Q2 Revision 2.

Evolution from Revision 1 to Revision 2: A 30-Year Journey

Significant development occurred over the 30 years separating ICH Q2 Revision 1 from Revision 2. Revision 1 was not truly a revision but rather a merger of two parts, and whilst not explicitly stated, it was largely directed at chromatographic methods. This focus left biological methods and bioassays underrepresented in the original guidance, creating substantial gaps for biopharmaceutical applications.

The emergence of Quality by Design principles, risk management approaches, and lifecycle concepts necessitated substantial revision to reflect new developments in analytical science and regulatory thinking. The shift from guidance focused primarily on chromatography to more general validation guidance applicable across diverse analytical techniques represents a significant advancement. This broader scope better accommodates the diversity of analytical methods employed in modern pharmaceutical development and manufacturing.

ICH guidelines generally establish minimal requirements rather than prescriptive mandates. Whilst Revision 1 showed what needed to be provided in regulatory dossiers, practitioners could always go further if scientifically justified. Revision 2 provides greater flexibility, explicitly permitting approaches that were previously possible but not formally acknowledged. For example, combining accuracy and precision evaluation is now recognised as acceptable practice, though it could have been done previously without regulatory objection.

The revision also better embraces classical practices developed across industry over many years. Combined with ICH Q14 on analytical procedure development, these guidelines provide excellent tools for formalising practices that companies should have been implementing all along. The revision represents codification of sound scientific practice rather than revolutionary change.

Formalising Scientific Responsibility and Process

Revision 2 includes considerably more text emphasising that scientists are responsible for validation plans and their content. Whilst this responsibility may seem obvious to experienced practitioners, explicitly stating it serves important purposes. The addition bridges gaps from Revision 1, which nowhere mentioned acceptance criteria or validation protocols despite these becoming standard practice as general GMP requirements.

Validation, like clinical trials or process validation, requires starting with a protocol stating objectives, methods for achieving them, and data collection plans. This framing positions validation as a scientific process rather than a mere checklist exercise. Including such fundamental requirements addresses both GMP compliance and scientific rigour, ensuring validation is conducted systematically rather than as a box-ticking activity.

The explicit statements may reflect that common sense is not always commonly applied. By stating fundamental requirements clearly, the guideline reduces ambiguity and reinforces proper scientific and regulatory practice. All validation activities require protocols defining what will be achieved, how it will be accomplished, and what data will be collected as part of the scientific and regulatory process.

Prior Knowledge and Development Data: Broadening the Evidence Base

ICH Q2 Revision 2 allows use of prior knowledge, even including this concept in figures linking Q14 to Q2. This provision raises questions about what constitutes acceptable prior knowledge for validation purposes. The term has broad meaning encompassing both general knowledge from experience with other molecules and products, and specific knowledge and data from the development phase of the current analytical procedure.

General knowledge derives from organisational experience across multiple products and methods, while specific knowledge relates directly to the procedure under validation. Development phase data can be used directly for validation without duplication, avoiding redundant work for aspects already well understood. However, implementing this approach requires organisational courage, as companies must decide whether to leverage existing data or play safe by repeating studies in formal validation protocols to avoid potential regulatory questions.

This approach somewhat violates traditional GMP sequences of protocol development, data generation, and evaluation. Questions may arise about using data generated before validation protocols existed. The lifecycle approach and analytical target profile concept provide essential links addressing this concern. Defining measurement requirements before selecting specific methods creates a framework justifying use of development data. Once requirements are defined through the analytical target profile, they cannot be arbitrarily changed, providing continuity between development and validation.

Unfortunately, ICH decided against merging Q2 and Q14 into a truly integrated lifecycle approach, keeping them separate despite partial misalignment. This separation represents a significant deficiency, as real lifecycle approaches require seamless integration between development and validation activities.

Justification for using prior knowledge will prove critical. Strong justification is required when including development data without preceding validation protocols. Regulatory feedback on this practice remains limited, but emphasis will likely increase as implementation progresses. Scientific tools addressing how to justify prior knowledge from development or similar molecules will be needed, though such practices are currently less common than traditional approaches. Conferences and other forums may develop guidance on proper justification methods as experience accumulates.

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