The International Council for Harmonisation (ICH) has endorsed the eCTD – the electronic common technical document – as the message standard for electronic submissions. This article presents an in-depth analysis of the implementation journey of the eCTD version 4.0 (eCTD v4.0) based on industry involvement in the Japanese Pharmaceuticals and Medical Devices Agency (PMDA) and the US Food and Drug Administration (FDA) technical pilots. It highlights the importance of harmonizing metadata, managing two different eCTD formats during the transition period, and ensuring interoperability between vendor tools and regulatory systems. Analyses of the eCTD v4.0 specifications are based on the authors' practical experience in submitting sequences in eCTD v4.0 format in Japan, industry involvement in the planning and preparation of eCTD v4.0 implementation, and limited participation during PMDA and FDA technical pilots.
