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FDA has Updated eCTD Guidance to Recommend Structure-Data Files

Jul 25, 2023 | Drug & Biologic Product Submissions, Pharmaceutical and Cosmetics


In November of 2022, the Food and Drug Administration (FDA) published a new version of the eCTD TECHNICAL CONFORMANCE GUIDE, amending it to include a new section. This new section, 3.3.3, focuses exclusively on structure-data files.

According to the new section, “Depending on the needs of the submission, include chemical structures of drug substances, drug products, impurities, starting materials, intermediates, metabolites, and leachables in Module 3 in a Structure-Data File (SD File).”

The SD file format is now being recommended for electronic Common Technical Document (eCTD) submissions, as part of FDA’s initiative to enhance the efficiency of reviewing eCTD submissions for drug approval. The SD format provides significant benefits, as it offers a computer-readable format necessary for the Quantitative Structure-Activity Relationship (QSAR) analysis review, an essential component of drug assessment. By submitting chemical structures in the SD format, the need for FDA reviewers to manually redraw images is eliminated, saving valuable time and reducing the risk of introducing errors during the review process.

Moreover, the SD format enables powerful searching capabilities, allowing FDA reviewers to quickly access relevant information during the assessment process. This shift to the SD file format is expected to streamline and expedite the review of submissions, ultimately resulting in a more efficient and accurate regulatory process. Consequently, drug approval timelines may be reduced, making it possible to bring new medications to patients more swiftly and reliably.

What is a Structure-Data File?

Structure-Data (SD) File is a nonproprietary file format used to encode chemical structure data using the molfile connection table format (J. Chem. Inf. Comput. Sci. 1992, 32, 3, 244–255). This format depicts chemical structures using a block of text that lists the atoms, bonds, connectivity, coordinates, and attributes. SD File is also commonly called an “.sdf” or “SDF.” All SD Files should use .sdf as the file extension and use the v2000 connection table format.

What is eCTD?

The Electronic Common Technical Document, commonly referred to as eCTD, is a standard format for submitting regulatory applications, amendments, supplements and reports to Global Health Authorities. eCTD is structured into five modules of information and data relating to a medicinal product and allows for electronic submission from applicant to regulator using an XML backbone as a navigation file and for effective version control.

Reed Tech is now offering eCTD services. Reed Tech has recently announced a pharmaceutical services expansion, including eCTD publishing services. These services include, but are not necessarily limited to:

  • Comprehensive eCTD Submissions
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For questions about eCTD, Structure-Data files or the new section 3.3.3, please reach out to [email protected] or +1-215-557-3010. To schedule an eCTD consultation, click here.