An Investigational Medicinal Product (IMP) is an investigational product studied in a clinical trial or used as a comparator or placebo. This also includes dosage forms and packaging specifically manufactured or labeled for the study. The term is central to planning, logistics, quality assurance, and regulatory compliance in pharmaceutical development.
What Qualifies as an IMP? Definition and Practical Examples
In the EU, IMPs typically include:
- the investigational medicinal product (test product), including various strengths/dosage forms,
- comparator products (active comparator) and placebo, if used within the scope of the study,
- investigational products with study-specific labeling and packaging (e.g., randomization numbers, blind codes).
Concomitant medications used outside the study design (e.g., standard therapies as background treatment) are generally not considered IMPs, unless they are part of the investigational treatment. However, this distinction is not only conceptual but also practically relevant, as the requirements for manufacturing, release, traceability, and documentation are significantly higher for IMPs.
In practice, classification as an IMP often leads to follow-up questions: Is repackaging required to support language requirements, blinding design, or randomization? If an authorized product is modified in a “study-specific” manner (e.g., by relabeling), additional GMP steps and a stricter documentation chain arise. These points should be aligned during study start-up with the manufacturer/CMO, the depot, and the clinical operations unit.
GMP, Labeling, and QP Release
IMPs must be manufactured under an appropriate quality system. In the EU, Good Manufacturing Practice (GMP) serves as the regulatory framework. Particularly important is the release by a Qualified Person (QP), who confirms that manufacturing and testing comply with applicable requirements and that batch documentation is complete.
In practice, this means that even if an active substance or a finished medicinal product is already approved, it can become an IMP through repackaging, relabeling, or study-specific blinding measures. This often results in an additional GMP scope that must be considered early in study planning.
The quality, non-clinical data, and clinical information regarding the IMP are described in the application documents for the clinical trial. Depending on the context, the Investigational Medicinal Product Dossier (IMPD) is used, among other documents; the Investigator’s Brochure and the clinical trial protocol also play an important role. The goal is for authorities and ethics committees to understand the risks associated with IMP use.
Under EU Regulation 536/2014 (Clinical Trials Regulation, CTR), this information is submitted and evaluated via CTIS. In Germany, national requirements are also relevant, for example, regarding language, document formats, or the involvement of competent authorities.
Operationally, the regulatory documents should align with the actual supply reality: for example, if the specification in the IMPD describes a certain stability assumption or storage condition, the shipping concept (including temperature mapping and qualification of shipping solutions) must match. Discrepancies between documentation and practice are a typical trigger for deviations.
Supply Chain, Randomization, and Documentation
IMPs are a key focus of operational study logistics. Typical tasks include:
- forecasting per investigational site, including buffers for screen failures and drop-outs,
- distribution in compliance with temperature and transport requirements,
- randomization and blinding, often supported by IXRS (Interactive Response Technology),
- traceability down to batch and package level, as well as regulated returns and destruction.
A common practical error is delayed coordination between the sponsor, CRO, manufacturer/CMO, and depot. If the randomization strategy, pack design, and shipping concept do not align, bottlenecks, protocol deviations, or – in the worst case – unblinding may occur.
Relevance for clinical trials
From the sponsor and CRO perspective, the IMP is the “common thread” between regulatory strategy and operational implementation: it links requirements from GMP, CTR/CTIS, pharmacovigilance (e.g., safety reporting related to the investigational medicinal product), and trial conduct at the investigational site. Full-service CROs such as mediconomics support the systematic planning of the IMP lifecycle—from QP release and depot logistics through to complete documentation (e.g., IMP accountability and reconciliation with source data).
The relevance is particularly evident in deviations: missing temperature logs, unresolved relabeling processes, or incomplete returns can lead to findings in audits and GCP inspections. A robust IMP setup reduces the risk of supply shortages delaying recruitment or requiring protocol-non-compliant adjustments (e.g., emergency resupply outside the defined chain).
Frequently Asked Questions (FAQ)
Is a placebo always an IMP?
Yes, if it is used as part of the study design within the clinical trial, a placebo is generally considered an IMP. In this case, placebo packages are also subject to requirements for labeling, traceability, and documentation.
When does an approved medicinal product become an IMP?
An already approved medicinal product can become an IMP if it is used as an investigational or comparator product in the study, or if study-specific changes are made (e.g., repackaging, relabeling, blinding). The context of its use in the clinical trial is decisive.
What documents are typically required for an IMP?
Frequently required documents include the IMPD, Investigator’s Brochure, information in the clinical trial protocol, and batch-related manufacturing and testing documentation. In the EU, essential documents are submitted via CTIS under CTR 536/2014.
Regulatory References
- Regulation (EU) No 536/2014 (Clinical Trials Regulation, CTR): Requirements for the application, assessment, and conduct of clinical trials, including investigational medicinal product documentation.
- ICH E6(R3) Good Clinical Practice: Roles and responsibilities, quality management, and documentation in the context of clinical trials.
- EudraLex Volume 4 (EU GMP Guide): GMP requirements and QP release for the manufacture and supply of investigational medicinal products.