Any medicinal product that is being tested or used as a reference in a clinical trial.
IMPs include newly developed drugs but also licensed drugs that are being tested against a new condition, or in a new formulation or packaging, or are being used to gather more information about the authorised form. Regulatory authorities mandate specific procedures for manufacturing and handling of IMPs, to ensure their quality and safety and hence the validity of clinical trial data.
Definition of Investigational Medicinal Product (IMP) and use of Auxiliary Medicinal Products (AMPs) (European Commission)
The rules governing medicinal products in the European Union Volume 10 – Guidance documents applying to clinical trials guidance on investigational medicinal products (IMPS) and ‘non investigational medicinal products’ (NIMPS) (European Commission, 2011)