Analysis of IMPD Deficiencies in the Clinical Trial Approval Process.

The Investigational Medicinal Product Dossier (IMPD) represents a foundational component of the pharmaceutical and analytical quality documentation required for the approval of clinical trials. Situated within the broader structure of the Common Technical Document (CTD), the IMPD provides essential data on the quality, manufacture, control, and stability of both the active substance and the finished product. This paper presents a comprehensive evaluation of the most frequently identified IMPD deficiencies cited by regulatory authorities between 2015 and 2024. A retrospective analysis of 74 deficiency letters issued for 26 clinical trials during the initial clinical trial application (CTA) reveals prominent shortcomings, including inadequately justified or incomplete specifications, missing or insufficient stability study data, and incomplete descriptions of manufacturing controls and critical process parameters. These deficiencies were identified across drug substances of chemical and biological origin, advanced therapy medicinal products (ATMPs), and a diverse range of pharmaceutical dosage forms.