Assessment and Control of DNA Reactive (Mutagenic) Impurities in Pharmaceuticals to Limit Potential Carcinogenic Risk
ICH M7 provides a framework to assess and control DNA reactive (mutagenic) impurities that may be present in drug substances and drug products, to limit potential carcinogenic risk. It sets out hazard assessment using (Q)SAR methodologies, impurity classification (Classes 1-5), the threshold of toxicological concern (TTC), and acceptable intake calculations including less-than-lifetime (LTL) limits. The R2 revision expands the addendum of compound-specific acceptable intakes.
What this does not cover
stated in the document's own scope- Does not itself set N-nitrosamine specific acceptable intakes — those are in separate guidances
- Does not cover non-mutagenic impurities — see ICH Q3A/Q3B
- Does not address elemental impurities — see ICH Q3D
- Does not prescribe the analytical method; validation is per ICH Q2(R2)
Always verify against the current published text before relying on it for a submission or inspection.
Overview
ICH M7 provides a harmonised framework for assessing and controlling DNA reactive (mutagenic) impurities in pharmaceuticals to limit potential carcinogenic risk. It covers hazard identification using structure-based assessment, in-silico (Q)SAR predictions from two complementary methodologies, and expert review; classification of impurities into five classes; and the derivation of acceptable intakes using the threshold of toxicological concern (TTC) and compound-specific limits, including less-than-lifetime exposure adjustments. It describes control options ranging from analytical testing to purge-based arguments where formation and fate justify no routine control. The R2 revision extends the addendum of compound-specific acceptable intakes.
Legal basis & how it acquires force
As an ICH guideline, M7 is given effect through adoption by regulatory members: an FDA guidance for industry in the US and a CHMP-adopted guideline in the EU, among others. It interprets the underlying quality expectations for impurity control under GMP and the marketing-authorisation framework, and it complements ICH Q3A/Q3B (impurities) for the specific case of mutagenic impurities rather than superseding them.
Document structure
| Part | Covers |
|---|---|
| Introduction and scope | Applicability to new and certain marketed products; clinical development considerations |
| Hazard assessment | Database/literature review and two (Q)SAR methodologies with expert review |
| Impurity classification | Classes 1-5 based on mutagenic/carcinogenic knowledge |
| Acceptable intakes | TTC, compound-specific limits, less-than-lifetime and multiple-impurity limits |
| Control strategy | Options 1-4 for controlling identified mutagenic impurities |
| Addendum | Monographs of compound-specific acceptable intakes |
Key requirements
- Perform hazard assessment of actual and potential impurities using two complementary (Q)SAR methodologies
- Classify impurities into Classes 1-5 based on mutagenic and carcinogenic potential
- Apply the TTC-based acceptable intake of 1.5 ug/day as a default where compound-specific data are absent
- Use compound-specific acceptable intakes (addendum) or LTL limits where justified
- Define a control strategy (Options 1-4) for each relevant impurity
- Document expert review to resolve out-of-domain or conflicting (Q)SAR predictions
- Address the total mutagenic impurity limit and multiple-impurity considerations
Implementation tips
- Retain the (Q)SAR run records and the expert review rationale — the conclusion alone is not defensible
- Justify Option 4 (no analytical control) with a robust purge argument, not just a low predicted level
- Keep M7 assessment current when a route or supplier changes — new potential impurities can appear
- Read M7 alongside the separate nitrosamine guidances; M7 is the framework, not the full N-nitrosamine limit set
International alignment
M7 is harmonised across ICH members and implemented regionally (FDA guidance, EU CHMP guideline, Japan). It is designed to be used alongside ICH Q3A/Q3B on impurities and connects to the broader nitrosamine control efforts, though dedicated N-nitrosamine limits are addressed in separate regional guidance.
ICH M7(R2): frequently asked questions
Quick answers to common questions about ICH M7(R2).
What is the default TTC-based acceptable intake?
A default of 1.5 micrograms per day is applied where compound-specific carcinogenicity data are not available.
How many (Q)SAR methodologies are required?
Two complementary methodologies (one expert rule-based, one statistical), with expert review to resolve conflicts.
What does the R2 addendum add?
It expands the set of compound-specific acceptable intake monographs.