Insights

The public consultation on the revised ICH Q1 Guideline, “Stability Testing of Drug Substances and Drug Products,” officially closed on 30 July 2025, marking an important milestone in the evolution of this essential regulatory framework. Initiated on 11 April 2025 with Step 2b of the ICH process, the draft was made available for stakeholder input by the EMA at the end of April.

This comprehensive revision unifies and replaces the former Q1A–F and Q5C guidelines. Crucially, it extends its applicability to both synthetic and biological entities, including advanced therapies such as vaccines, gene therapies, and combination products. One of the most significant advancements is the introduction of lifecycle stability management, aligning with principles set forth in ICH Q12.

Among the most impactful updates are the inclusion of all climatic zones for global harmonization, clear guidance for stability in clinical settings, and dedicated sections for Advanced Therapy Medicinal Products (ATMPs). The emphasis on Quality by Design and risk-based methodologies reflects a strong alignment with ICH Q8–Q11 and the emerging Q14, underscoring a more strategic integration of stability into the broader drug development process.

As the ICH process moves forward, stakeholders across R&D and regulatory functions should prepare for changes that may affect dossier strategies, development timelines, and global submissions.

RPN will provide any further update and is available to provide full support for drug development and regulatory strategy activities.