Developing a new medicine requires rigorous testing through structured human studies known as clinical trials. At the core of this complex process is the Investigational Medicinal Product (IMP). The IMP is the pharmaceutical substance being evaluated for safety and efficacy. Its systematic handling and documentation are central to ensuring that the clinical data collected is accurate and reliable for regulatory review.
Defining the Investigational Medicinal Product
An Investigational Medicinal Product is formally defined as a pharmaceutical form of an active ingredient, or a placebo, that is being tested or used as a reference in a clinical study. This definition is expansive and is not limited only to newly created chemical compounds. The “Investigational” status means the product is not yet approved by regulatory bodies for the specific use or indication being studied.
This category frequently includes licensed medicines being repurposed, such as testing an existing drug for a new disease or in a different patient population than its original approval. It also covers approved drugs used in a modified way, such as a new dosage form, a different route of administration, or altered packaging. The IMP designation applies to any product used to test a scientific hypothesis, which includes the active drug, the placebo, and any established treatment used as an active comparator in the study.
It is helpful to contrast the IMP with other medications a patient may receive during a trial. Medications administered as standard care for the patient’s underlying condition, or for symptom relief, are classified as Non-Investigational Medicinal Products (NIMPs) or Auxiliary Medicinal Products (AxMPs). These auxiliary products are not being tested as part of the study hypothesis, so they do not carry the same stringent IMP handling and accountability requirements. The distinction is based on the product’s intended use and its role in answering the trial’s primary research question.
The Critical Role of IMP Management
The management of the IMP supply chain is a specialized logistical operation designed to protect the integrity of the product and the scientific validity of the trial. This process begins with manufacturing, which must adhere to strict quality standards to ensure consistency across all batches used in the study. From there, the product moves through a complex distribution network involving packaging, labeling, and shipment to clinical sites worldwide.
A significant challenge in IMP management is maintaining the blinding of a study, where neither the patient nor the site staff knows who is receiving the active drug versus the control. This is achieved by packaging the IMP, the placebo, and any active comparator to be physically indistinguishable, often requiring over-encapsulation or re-packaging of commercial medicines. Each package is assigned a unique code linked to a randomization system, which preserves the treatment assignment until the trial’s conclusion.
Maintaining the product’s stability is a requirement throughout the supply chain. Many IMPs, particularly complex biologics or novel therapies, are temperature-sensitive and must be stored within a narrow range, such as refrigerated (2°C to 8°C) or frozen. Shipments are tracked with temperature data loggers that provide a continuous record of thermal exposure. Any temperature excursion that exceeds the approved range triggers a quarantine of the product until its viability can be scientifically assessed.
Beyond physical handling, a meticulous system of drug accountability tracks every single unit of the product. This begins with documenting the receipt of the IMP at the site, its dispensing to the patient, and the tracking of any unused or partially used product returned by the patient. These detailed records ensure that sponsors can verify that the correct quantity of product was used, which is an element of regulatory compliance and data credibility.
Ensuring Patient Safety and Product Integrity
Regulatory bodies enforce specific requirements for IMPs to prioritize patient safety and maintain a clear audit trail. A visible component of this is the specialized labeling mandated for all investigational products. The label must clearly state “For Clinical Trial Use Only” or equivalent wording to distinguish it from a commercial product and prevent misuse outside the study protocol.
In addition to the cautionary statement, the label must include several key details. These details ensure immediate traceability and provide necessary instructions for proper handling and storage:
- The trial’s reference code.
- The batch number.
- The expiry date.
- The specific storage conditions required.
- Contact information for the sponsor or investigator.
- A unique patient identification code (where applicable).
Throughout the trial, products that become expired, contaminated, or damaged must be immediately segregated from usable stock in a secure quarantine area. The handling of these products is controlled and documented to ensure they are never administered to a patient. This process is part of a broader accountability system that culminates in the final reconciliation and destruction of all unused or returned IMP.
Final accountability requires the sponsor to reconcile the total quantity of product manufactured and shipped against the quantity dispensed, remaining, and returned. Once reconciliation is completed and any discrepancies are resolved, the sponsor is authorized to destroy the remaining product. Destruction must be performed by a licensed waste facility, and a formal Certificate of Destruction is generated to prove that no unaccounted-for product remains in circulation.