Module 2 of the EAEU Registration Dossier — How to Write a CTD Summary That Accelerates Drug Assessment
A regulatory affairs department often spends months on Module 3 of the registration dossier: verifying specifications, compiling validation reports, structuring stability data. Module 2 is frequently written during the final week before submission, as a formal retelling of what is already presented in the remaining modules. This time-saving tactic turns out to be more costly than it appears during the preparation phase.
The CTD Summary is the first substantive document an assessor opens after verifying the administrative data in Module 1. For quality assessment, the assessor uses a dedicated quality critical-assessment report template (Annex No. 8 to the Rules of Registration), structured along the same lines as the Quality Overall Summary in Section 2.3: data are broken down separately for each active pharmaceutical substance (explicitly designated as Section 3.2.S in the report template) and separately for the finished drug product. If the applicant submits a dry compilation of tables without explanations instead of a genuine summary, the assessor has to reconstruct the missing analysis independently. Every such gap turns into a request for supplementary information, and each request prolongs the review timeline.
Treating the Summary as a Formality — The Most Common Mistake of a Regulatory Department
Specialists accustomed to working with Module 1 (administrative information) and Module 3 (quality data) often apply the same mindset to Module 2: fill out the template, insert the data, submit. The Registration Rules define Module 2 differently. Under Paragraph 2 of Annex No. 1 to Decision No. 78 of the Council of the Eurasian Economic Commission dated 3 November 2016 (hereinafter, Decision No. 78), this module must provide summaries of the quality, non-clinical, and clinical documentation with cross-references to Modules 3-5, and the overviews must comply with the general principles and requirements set out in the Rules. The wording is dry, but the meaning is direct: overview sections must contain an evaluation of the data, not just a retelling of facts.
In practice, the same shortcomings recur.
The non-clinical or clinical overview copies tables directly from Modules 3-5 without commentary, without explaining why the chosen study strategy was appropriate. Cross-references to source modules are inaccurate or missing entirely, forcing the assessor to locate the required table manually. Deviations from standard study scope requirements go unexplained, even though Section 2.3 of the Rules explicitly requires justification for such cases. The clinical overview avoids unresolved questions on efficacy and safety, even though Section 2.5 requires that these issues be disclosed directly, without vague language. The Introduction to the CTD (Section 2.2) runs several pages instead of the single page set out in the Rules, turning into a duplicate of the introduction from the Summary of Product Characteristics.
Each of these errors looks minor on its own. Together, they create an impression that the applicant assembled the dossier from pre-made pieces and did not analyze it.
The difference between retelling and analysis is visible in a single sentence. Retelling: «The study noted an increased incidence of headache in the treatment group compared to placebo.» Analysis: «The increased incidence of headache in the treatment group showed no dose-dependent effect and resolved without treatment within 48 hours; this profile is already reflected in the ‘Undesirable effects’ section of the product information.» The first version states a fact from a Module 5 table. The second shows that the applicant understood the significance of that fact for the safety profile and accounted for it in the product labeling — which is exactly what Section 2.5 of the Rules requires.
The Seven Sections of the CTD Summary
Decision No. 78 sets out the structure of Module 2 through seven mandatory sections in a strict order. A general introduction to the product (pharmacological class, mechanism of action, proposed clinical use) must precede these sections and must not exceed one page.
| Section | Content | What to Watch For |
|---|---|---|
| 2.1 Table of Contents (Modules 2-5) | Full table of contents for quality, safety, and efficacy documentation | Required only for the paper dossier; not provided in the electronic CTD |
| 2.2 Introduction to the CTD | Pharmacological group, mechanism of action, proposed clinical use | Must not exceed one page |
| 2.3 Quality Overall Summary | Overview of chemical, pharmaceutical, and biological data, significant parameters, justification of deviations from requirements and guidelines | The applicant chooses the level of detail, depending on the complexity of the product |
| 2.4 Non-clinical Overview | Integrated and comprehensive assessment of animal and in vitro studies, evaluation of impurities and degradation products, justification of relevance to the intended clinical use | Safety of any new excipient is assessed separately |
| 2.5 Clinical Overview | Detailed analysis of clinical data, study design and conduct, benefit-risk assessment, justification of dose and indications | Unresolved efficacy and safety questions must be stated directly |
| 2.6 Non-clinical Summary | Six subsections: pharmacology, pharmacokinetics, and toxicology, each in both written and tabulated format | Strict sequence of subsections, as set out in the Rules |
| 2.7 Clinical Summary | Biopharmaceutic studies, clinical pharmacology, efficacy, safety, literature used, brief overview of individual studies | Six subsections must follow the specified order, including the list of scientific sources |
Section 2.3 deserves particular attention. The Rules explicitly allow the applicant to choose the level of detail for the Quality Overall Summary depending on the product’s complexity. This is a deliberate flexibility built into the structure of the section itself. A straightforward generic with a well-characterized substance does not need the same depth of analysis as a biological product with several manufacturing sites. The opposite mistake, a two-page, formal summary for a complex product, raises more assessment questions than the time it saves in preparation.
The Clinical Overview (Section 2.5) must contain an analysis of the data included in the summary and in Module 5, the course of clinical development, the decisions made in study design, and an explanation of all efficacy and safety questions that arose during development and were not resolved. The Rules require that limitations be listed openly, and that the summary show how the summary of product characteristics and the patient information leaflet address these limitations.
How Documents Are Split Into Files in the Electronic Dossier
The CTD organization scheme in Annex No. 1 sets out not only the content of sections but also the level at which documents can be merged or must be split. For a regulatory department preparing an electronic registration dossier (eCTD), this granularity matters as much as the content requirements.
Section 2.3 (Quality Overall Summary) must consist of a separate document for each pharmaceutical substance, even if the product contains several active ingredients. If a medicinal product is supplied together with solvents for reconstitution, information on the solvent is placed in a separate part of the «P» document, without mixing it into the main substance summary. Section 2.7.3 (Summary of Clinical Efficacy) requires a separate document for each indication, although closely related indications may be combined into one document. Section 2.1 (Table of Contents for Modules 2-5) is needed only for the paper version of the dossier and is not compiled at all in electronic format.
These rules affect how the assessor navigates the eCTD. A document that merges data for several substances into a single Section 2.3 file forces the assessor to separate the information manually, though the dossier structure was meant to handle this automatically.
How the Summary Differs for Generics, Hybrids, and Biosimilars
The required content of Sections 2.4 and 2.5 depends on the product’s regulatory status, which affects the regulatory department’s workload from the planning stage.
For a generic medicinal product (Section 6.2 of Annex No. 1), the non-clinical and clinical overview must additionally include a summary of the impurity profile of the active substance in commercial batches and an assessment of bioequivalence studies, or an explanation for their absence. It also requires an update of the published literature on the active substance and, if the chemical form of the active substance differs from the reference product (a different salt, ester, or isomer), evidence that this does not change the safety and efficacy profile. For a hybrid product (Section 7.2), the set of requirements is nearly identical, following the same logic: the overview must explain how the hybrid product differs from the original and support those differences with data.
For products with well-established medical use (Section 8 of Annex No. 1), the applicant submits Modules 1, 2, and 3 as usual, and replaces the non-clinical and clinical study reports in Modules 4 and 5 with scientific bibliography. In this situation, the non-clinical and clinical overviews in Module 2 carry the main evidentiary weight.
The Rules name four factors that must be addressed in these overviews:
the period during which the active substance has been used in medical practice (at least 10 years of documented use in at least three Member States);
quantitative aspects of the active substance’s use;
the frequency of scientific publications and the continued relevance of the active substance’s use in the 5 years before the application date, with references to sources;
consistency of scientific assessments across different sources.
For a biosimilar product (Section 10.2), the quality, non-clinical, and clinical overviews must additionally include comparative information on the proposed and reference products, along with the criteria for selecting the latter. The Rules require a specific set of details about it: trade name, strength and dosage form, marketing authorization holder, registration date and authorization number, Member States of registration, batch number used in the studies, manufacturer, shelf life, and country of purchase. Without this list, the justification for the selection is considered incomplete, no matter how thoroughly Module 3 is compiled.
A separate situation arises during the procedure for aligning a registration dossier with Union requirements, relevant for products previously registered under national rules. Here, Module 2 does not necessarily need to be rewritten from scratch: Section 11.1 of Annex No. 1 allows it to be submitted as overview sections with an update on changes, formatted as an addendum, or in full at the applicant’s own initiative. The choice of format should be deliberate: the addendum saves preparation time, while a full revision of the summary sometimes removes questions that would otherwise come up during assessment.
Actionable Recommendations
Write Module 2 after finalizing the drafts of Modules 3-5, not in parallel with them. Every statement in Overviews 2.3-2.5 must rest on a precise cross-reference to a specific section or table in the source module. References inserted early and not checked against the final data revision are a common cause of discrepancies during assessment.
Determine the product’s regulatory status before starting work on the summary. A generic, a hybrid product, a biosimilar, or a product with well-established use each has its own mandatory dataset for Sections 2.4 and 2.5. Planning this scope of work after the fact, once the draft is already written from a generic template, almost always means rewriting the overviews from scratch.
Check the length of the CTD Introduction and the document boundaries within Section 2.3. The Introduction (2.2) must not exceed one page. The Quality Overall Summary (2.3) is organized as a separate document for each pharmaceutical substance, and information on reconstitution solvents is not merged into the main document.
Choose the level of detail for the Quality Overall Summary in proportion to the product’s complexity. For a simple generic with a pharmacopoeial substance, excessive detail in Section 2.3 adds no value. For a biological product or a product with several manufacturing sites, an overly condensed summary directly invites a request from the assessor.
Cross-check the Quality Overall Summary (Section 2.3) against the quality critical-assessment report template (Annex No. 8 to the Rules). The template is built on the same principle and works as a ready-made checklist: if a point in the template is not addressed in your summary, the assessor will raise it as a separate request.
The assessor opens the CTD Summary first, and it shapes the first impression of the quality of the entire dossier. A regulatory department that treats Module 2 as an independent analytical document reduces the number of assessment requests and the time to registration. A summary written in haste simply postpones that work, until it has to be done under pressure of a deadline for responding to the assessor.
Regulatory Framework:
1. Decision No. 78 of the Council of the EEC dated 3 November 2016 (as amended on 26 November 2025), «On the Rules of Registration and Examination of Medicinal Products for Human Use,» Annex No. 1, «Requirements for Registration Dossier Documents (in the Common Technical Document Format),» Sections 2, 6.2, 7.2, 8, 10.2, 11.1
2. Decision No. 78 of the Council of the EEC, Annex No. 8, «Expert Report Form on the Critical Assessment of the Quality Aspects of a Medicinal Product»