eCTD (Electronic Common Technical Document)

The electronic Common Technical Document (eCTD) is the standardized electronic submission format that FDA and other ICH regulatory authorities require for structuring applications such as New Drug Applications (NDAs), Abbreviated New Drug Applications (ANDAs), Biologics License Applications (BLAs), Investigational New Drug applications (INDs), and Drug Master Files (DMFs). It is the electronic implementation of the paper-era Common Technical Document (CTD) harmonized format developed under the International Council for Harmonisation (ICH), organizing a submission into a fixed five-module folder hierarchy plus an XML backbone that gives reviewers a hyperlinked table of contents and tracks the document’s lifecycle across amendments.

The five-module hierarchy

Every eCTD submission follows the same top-level structure, regardless of application type:

• Module 1 — Administrative and regional information. The only module that is not harmonized internationally; its contents are defined by each regulatory authority rather than by ICH. For FDA, Module 1 holds the application’s cover forms and correspondence — including FDA Form 356h for NDA/ANDA/BLA submissions, or Form FDA-1571 as the cover sheet for an Investigational New Drug (IND) application — along with labeling, meeting requests, annual reports, and other US-specific administrative content.
• Module 2 — CTD summaries. Overview and summary documents (Quality Overall Summary, Nonclinical Overview/Summary, Clinical Overview/Summary) that synthesize the detailed data in Modules 3-5 for reviewers.
• Module 3 — Quality. Chemistry, manufacturing, and controls (CMC) data for the drug substance and drug product, structured per the ICH M4Q guideline.
• Module 4 — Nonclinical study reports. Pharmacology, pharmacokinetics, and toxicology study reports, structured per ICH M4S.
• Module 5 — Clinical study reports. Clinical study protocols and reports, including full Clinical Study Reports (CSRs) prepared under the ICH E3 structure, plus other clinical data.

Modules 2-5 are harmonized across ICH regions (the same structure applies whether the submission goes to FDA, EMA, or another ICH regulatory authority); Module 1 content and organization is set independently by each authority.

XML backbone and lifecycle management

What distinguishes an eCTD from an ordinary electronic folder of documents is the XML backbone (an index.xml file and related XML metadata) that sits on top of the Module 1-5 folder tree. The backbone does two things a plain folder structure cannot: it builds the hyperlinked, navigable table of contents reviewers use to move through the submission, and it assigns a lifecycle operation — new, append, replace, or delete — to each individual file. That lifecycle metadata is what lets a sponsor submit an amendment, a safety update, or a new study report as an incremental addition to an existing application’s submission history, rather than resubmitting the entire dossier each time. FDA’s Electronic Submissions Gateway validates this structure on receipt; a submission that is missing the backbone or does not conform to the required hierarchy is rejected rather than processed.

Who is required to use eCTD

FDA’s Providing Regulatory Submissions in Electronic Format guidance made eCTD mandatory in stages: NDAs, ANDAs, BLAs, and Drug Master Files (new and existing) were required to be submitted in eCTD format beginning May 5, 2017; commercial INDs (those intended to eventually support marketing) followed on May 5, 2018. Once an application is under an active eCTD mandate, every subsequent submission to that application — amendments, annual reports, correspondence — must also be filed in eCTD format, even if the original application predates the mandate.

eCTD vs. CTD

The CTD is the harmonized content and organization standard itself, agreed by ICH; the eCTD is the electronic, XML-backboned implementation of that standard used for actual submission and lifecycle management. In practice, essentially all NDA/ANDA/BLA/IND traffic to FDA today is filed as eCTD rather than as a paper CTD, so the two terms are frequently used interchangeably in practice even though they describe distinct things — the content standard versus its electronic submission format.

Related CASRAI terms

See CASRAI’s entries on the Investigational New Drug (IND) application (which the eCTD’s Module 1 cover sheet, Form FDA-1571, accompanies), FDA Form 1572 (Statement of Investigator), FDA Form 356h (the NDA/ANDA/BLA cover form filed in Module 1), and the Clinical Study Report (CSR) (filed in Module 5) for how these pieces fit into a complete eCTD submission.