eCTD Submission Structure: What Every RA Professional Should Know

The electronic Common Technical Document (eCTD) is the internationally agreed format for submitting regulatory dossiers to health authorities worldwide. Whether you are filing with the EMA, FDA, or other ICH-region regulators, understanding the eCTD structure is fundamental to a smooth submission process.

What is eCTD?

The eCTD is an electronic format for the Common Technical Document (CTD), developed by the International Council for Harmonisation (ICH). It provides a standardized structure for organizing all the quality, safety, and efficacy information needed for a marketing authorization application.

The format uses XML backbone files to organize documents into a hierarchical structure, making it easier for regulators to navigate and review submissions. Since 2003, eCTD has been progressively adopted worldwide, and it is now mandatory for submissions to the EMA, FDA, and most major regulatory agencies.

The 5-Module Structure

The eCTD is organized into five modules, each covering a specific area of the regulatory dossier:

Module 1 — Administrative Information and Prescribing Information

Module 1 is the only region-specific module. It contains:

• Cover letters and application forms
• Product information (SmPC, package leaflet, labelling for EU; prescribing information for FDA)
• Fee payment documentation
• Patent information and exclusivity claims
• Environmental risk assessments (where applicable)

Because Module 1 varies by region, you'll need to prepare different versions for EMA and FDA submissions.

Module 2 — Common Technical Document Summaries

Module 2 is the heart of the CTD. It provides overviews and summaries of the detailed data in Modules 3, 4, and 5:

• 2.1 — CTD Table of Contents
• 2.2 — CTD Introduction
• 2.3 — Quality Overall Summary (QOS)
• 2.4 — Nonclinical Overview
• 2.5 — Clinical Overview
• 2.6 — Nonclinical Written and Tabulated Summaries
• 2.7 — Clinical Summary

Module 2 summaries are what reviewers read first, so invest significant effort in making them clear, well-structured, and internally consistent.

Module 3 — Quality

Module 3 contains all pharmaceutical quality data, organized into:

• 3.2.S — Drug Substance: manufacturing process, characterization, specifications, stability
• 3.2.P — Drug Product: formulation, manufacturing process, specifications, stability
• 3.2.A — Appendices: facilities and equipment, adventitious agents assessment
• 3.2.R — Regional Information
• 3.3 — Literature References

Module 4 — Nonclinical Study Reports

Module 4 contains full study reports for all nonclinical (preclinical) studies:

• Pharmacology studies (primary, secondary, safety)
• Pharmacokinetic studies (ADME)
• Toxicology studies (single-dose, repeat-dose, genotoxicity, carcinogenicity, reproductive toxicity)

Module 5 — Clinical Study Reports

Module 5 is typically the largest module, containing:

• Tabular listing of all clinical studies
• Clinical study reports (full reports for pivotal studies)
• Case report forms (for critical patients)
• Individual patient data listings

Practical Tips for eCTD Organization

1. Plan your structure early. Don’t wait until submission time. Start organizing documents into the eCTD structure during development.
2. Use consistent naming conventions. File names should be descriptive and follow a logical pattern. Most publishing software has naming rules you should follow.
3. Hyperlink between modules. Module 2 summaries should reference specific sections in Modules 3–5. This makes reviewer navigation much easier.
4. Manage lifecycle operations carefully. eCTD supports append, replace, and delete operations. Plan your sequence numbering and lifecycle management from the start.
5. Validate before submission. Always run your eCTD through a validation tool before submitting. Both EMA and FDA have specific technical validation criteria that must pass.

eCTD for Medical Devices

While eCTD was originally designed for pharmaceutical products, the structure is increasingly relevant for combination products and some medical device submissions. Under EU MDR, technical documentation for medical devices follows a different structure (Annex II and III), but manufacturers of drug-device combinations often need to prepare eCTD-format dossiers for the drug component.

Tip: Our eCTD Organizer tool helps you map your documents to the correct modules and identify gaps before submission.

Key Resources

• ICH M8: eCTD specification (the technical standard)
• EMA eCTD guidance: EU Module 1 specification and validation criteria
• FDA eCTD guidance: Technical specifications and regional requirements