The International Council for Harmonisation (ICH) has just hit a key milestone with the release of its Step 2 draft of ICH Q1: Stability Testing of Drug Substances and Drug Products—and is now open for public comment.
This long-awaited update is more than just a refresh. It completely reimagines how the pharmaceutical industry will approach stability testing moving forward, combining legacy guidance with modern expectations and technologies.
Here we break it all down.
What Is ICH Q1 and Why Was It Updated?
Stability testing is how we ensure that medicines remain safe and effective throughout their shelf life. It’s a critical part of regulatory submissions and ongoing product quality.
Over the years, ICH developed a series of guidelines—Q1A through Q1F and Q5C—that outlined the expectations for these tests. But with so many documents, things got complex and sometimes even contradictory.
The solution? ICH decided to unify and modernize these documents into a single, comprehensive guideline: ICH Q1.
The goals of the revision are clear:
- Simplify by combining multiple guidelines.
- Clarify existing ambiguities.
- Modernize with science-based, risk-driven approaches.
- Expand to include new product types like Advanced Therapy Medicinal Products (ATMPs).
Key Timeline Highlights
The ICH Q1 update didn’t happen overnight. Here’s a quick timeline of how we got here:
- Nov 2022 – Concept paper and business plan finalized.
- 2023 – Draft development, internal reviews, and gap analysis.
- Mar 2025 – Finalized Step 1 draft.
- April 2025 – Step 2 release for public comment (that’s now!).
The guideline will continue evolving through Step 3 and Step 4 before becoming final.
What’s New in the Draft?
The Step 2 draft of ICH Q1 brings all stability-related topics into one place, organized into 18 sections plus three annexes. It’s meant to be read as a whole for a complete understanding, but here are some key highlights:
1. Unified Framework
No more jumping between Q1A, Q1B, Q1C, etc. Everything is now integrated—making it easier to plan, conduct, and review stability studies.
2. Modernization of Content
Expect updated guidance on:
- Protocol design
- Storage conditions
- Photostability
- In-use and short-term stability
- Reference materials and novel excipients
Sections 3 to 7 are especially critical—they outline the core framework for designing and executing stability protocols.
3. New Areas of Focus
This draft includes entirely new sections on:
- Short-term storage (for products labeled with temporary conditions)
- In-use stability (how long a product stays effective after opening)
- Processing/holding times (how intermediate steps affect stability)
- Stability modelling (enhanced tools for predicting shelf life)
There’s also a brand-new Annex on ATMPs, recognizing the rise of cell and gene therapies.
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How to Review the Draft
Reviewers are encouraged to read the entire guideline—not just isolated sections—since some content has been reorganized. If something seems missing, it’s likely been moved elsewhere.
Key tips for reviewers:
- Be thorough – This guideline affects a wide range of products.
- Be specific – Use line numbers and section references in your feedback.
- Be helpful – If a comment is critical, explain why. If training might resolve it, say so.
Remember: don’t submit duplicate comments across multiple organizations—this only slows down the process for everyone involved.
The Commenting Process
Submitting comments? Here’s what to know:
- Use the ICH template or the one provided by your regional regulatory authority.
- Identify your organization, the lines you’re referring to, and your comment.
- If applicable, suggest changes or alternatives.
Critical comments should be clearly labeled and backed with solid reasoning.
Final Thoughts
The ICH Q1 revision is a major step forward for pharmaceutical quality. It brings consistency, flexibility, and modern thinking into the stability space—something that’s long overdue.
By combining past guidance and adding new insights, it sets the stage for a smarter, more streamlined approach to ensuring the safety and efficacy of drugs across their lifecycle.
Whether you’re in regulatory affairs, quality, R&D, or manufacturing, this is a document you’ll want to be familiar with—and one where your input can help shape the final version.
Ready to Review the Draft or Submit Feedback?
Visit the official ICH website to read the full guidelines and access the commenting tools.