On this page
How should the CTD 2.6 nonclinical summaries be organized?
Organize CTD 2.6 around a common product introduction and coordinated written/tabulated summary pairs for pharmacology, pharmacokinetics and toxicology. Begin with a reconciled inventory of the actual studies and report versions. The summary structure organizes evidence; it does not determine which studies a particular product must have.
Before you begin
Organization of acquired nonclinical evidence under M4S. This is not a study-requirement determination or an IND testing checklist.
What you will prepare: A reconciled summary plan and a concise nonclinical introduction, with missing evidence assigned to an owner.
Sections covered in this guide (2)
Inventory the evidence before allocating the writing
M4S describes a format for nonclinical information; it does not determine which studies a product needs. Begin with the actual study register, final report versions, development context and scientific decisions about omitted or alternative work. Treat “not performed,” “not applicable,” and “report not available” as different states.
Create a working inventory containing study identifier, discipline, objective, material, species/model, route, duration, report version and proposed summary location. Assign one owner to reconcile the register against Module 4. If a report is still being finalized, do not present its preliminary result as an approved conclusion.
The family heading 2.6 organizes the introduction and three written/tabulated pairs. It does not call for a fourth generic summary containing the same material. Give each pair a clear owner and agree common terminology before drafting begins.
Write 2.6.1 around the pharmaceutical and intended use
The introduction orients the nonclinical reader to the pharmaceutical, its structure and pharmacological properties, and the proposed clinical indication, dose and duration. Obtain these from controlled quality and clinical records. Use a structure representation appropriate to the product rather than forcing a complex biologic into a small-molecule template.
Explain abbreviations and development codes that the reader will encounter in the summaries. If the proposed dose is a range or depends on population, retain that condition. If it remains undecided, identify the missing decision and avoid using an obsolete dose as though it were final.
Keep study conclusions in their substantive summaries. The introduction should equip the reviewer to understand those results, not prejudge the safety interpretation.
Maintain one fact across the written and tabulated versions
Agree units, analyte names, dose notation and the treatment of study versions across disciplines. M4S supports cross-references from written summaries to the tabulated summaries and underlying report identifiers. Maintain those references in the source documents as well as the publication package.
Fictional editorial exercise: the pharmacokinetic writer receives an amended report, while the toxicology writer retains an exposure value from the earlier version. Compare the register’s controlling report with both outputs. Ask the responsible scientists whether the amendment changes interpretation, then update affected tables and narrative together.
If a report cannot be located, retain a visible gap in the review register and escalate it. Do not delete its row merely to make the totals reconcile. The inventory should reveal incomplete preparation, not conceal it.
Assign the writing package before drafting begins
Use one study inventory to commission the whole summary package. Separate authors can write the discipline-specific documents, but they need the same definitions for product identity, development codes, units and controlling report versions.
| Deliverable | Main question it answers | Handoff to reconcile |
|---|---|---|
| 2.6.1 introduction | What product and proposed clinical use orient this program? | Quality identity and the current clinical regimen |
| 2.6.2 / 2.6.3 pharmacology | What activity and unwanted pharmacological effects were investigated? | Study roles, assay context and matching written/table conclusions |
| 2.6.4 / 2.6.5 pharmacokinetics | What do disposition and exposure measurements represent? | Analyte definitions and toxicokinetic values used by other authors |
| 2.6.6 / 2.6.7 toxicology | What findings occurred under what study conditions? | Material, exposure, adversity and recovery interpretation |
| 2.4 overview | What does the program collectively mean for human use? | Important findings and limitations from all three pairs |
For the working inventory, use a status column with distinct values: report available, amendment pending, report unavailable, study not performed, and applicability under review. Do not collapse these into “N/A.” Record the owner and the decision needed for every unresolved item.
Release the summary pair only after a spot check in both directions: select a narrative conclusion and find its table/report support; then select a consequential table finding and find its narrative treatment. This catches a serious observation that is correctly tabulated but never discussed. The nonclinical overview should receive the final interpretation and limitation, not only a list of completed files.
For a lifecycle submission, confirm which evidence and documents are affected by the change. Reusing an unchanged file can be appropriate; treating an amended report as unchanged simply because its study number stayed the same is not a sound document-control decision.
Your preparation checklist
0/4 checkedUse this to track your review in this visit. Checks are not saved and do not establish regulatory compliance.
Frequently asked questions
Does every nonclinical study need its own Module 2 summary file?
Not necessarily. M4S organizes written and tabulated summaries by discipline and topic; those documents can describe multiple studies. Distinguish a scientific subsection, an electronic heading and an individual report. Confirm the applicable publishing granularity rather than creating a file for every inventory row.
Does a missing study category mean it is not applicable?
No. A study may be absent because it was not performed, its report is unavailable, or a product-specific scientific rationale supports a different approach. The writer should record the actual state and obtain the responsible expert’s rationale, rather than infer non-applicability from an empty folder.
What belongs in the nonclinical introduction in section 2.6.1?
Introduce the pharmaceutical, relevant structure and pharmacological properties, and the proposed clinical indication, dose and duration. Use the current quality and clinical descriptions. Do not substitute the conclusions of individual toxicology studies for the product context that allows the reader to understand those studies.
How should report amendments be handled across summary pairs?
Maintain the controlling version in the common study register, identify every table and narrative that uses the amended result, and ask the scientific owner whether interpretation changes. Update the affected summaries and overview together. An unchanged study identifier does not mean that an earlier result remains current.
Sources and revisions
Requirements, source recommendations and editorial preparation advice have different roles. Review the scope and revision of the source you use.
Guidance
ICH M4S(R2): Nonclinical overview and summaries ↗Step 4, December 20, 2002; sections 2.4 and 2.6 and Appendices A/B. FDA M4S and Safety Appendices remain labeled final, August 2001; ICH R2 includes subsequent editorial changes.
Technical specification · placement only
FDA eCTD v4.0 comprehensive hierarchy ↗Version 2.2, February 2025. Section 2.6. A heading identifies placement, not mandatory applicability.