An IMPD, or Investigational Medicinal Product Dossier, is a comprehensive document that compiles everything known about a drug being tested in a clinical trial. It covers how the drug is made, what safety testing has been done in the lab, and what clinical data exists so far. Regulatory authorities in the European Union require an IMPD as part of any clinical trial application, and they use it to decide whether a trial is safe enough to proceed with human participants.
Why the IMPD Exists
Before a new drug can be tested in people, regulators need proof that the product is well-characterized, consistently manufactured, and unlikely to cause unexpected harm. The IMPD serves as that proof. It is submitted through the EU’s Clinical Trials Information System under Regulation 536/2014, and every EU member state involved in a trial reviews it before granting approval.
The dossier isn’t just for brand-new compounds. Any product used as an investigational medicinal product in a trial, including placebos and already-approved drugs being tested for a new use, needs some form of IMPD documentation. The depth of what’s required depends on how much is already known about the product.
The Three Main Sections
An IMPD is organized into three broad areas: quality data, non-clinical data, and clinical data. Each serves a distinct purpose in building the case that the drug is fit for human testing.
Quality (Manufacturing) Data
This section describes the drug itself and how it’s produced. For the active ingredient, it includes a description of the substance’s physical and chemical characteristics, evidence supporting its identity and structure, a detailed flow diagram of the manufacturing process (listing reagents, solvents, and catalysts), and the testing methods used to verify identity, strength, purity, and quality. Certificates of analysis and stability data showing the substance holds up during storage are also expected.
For the finished product (the tablet, injection, or whatever form reaches the patient), the dossier lists every component used in manufacturing, describes the production and packaging process, and provides final specifications. Injectable products require additional testing for sterility, bacterial toxins, and particulate matter. Stability data must demonstrate that the product will remain safe and effective throughout the planned trial.
Non-Clinical (Laboratory and Animal) Data
Before a drug reaches human volunteers, it undergoes extensive laboratory testing. The non-clinical section summarizes how the drug behaves in animal models and in lab experiments. This includes the drug’s pharmacological effects and mechanism of action, along with data on how the body absorbs, distributes, breaks down, and eliminates it.
The toxicology portion is particularly detailed. It covers acute toxicity (what happens with a single high dose), subacute and chronic toxicity (repeated dosing over weeks or months), effects on reproduction and fetal development, and any special testing related to how the drug will be administered. If a drug is inhaled, for example, inhalation-specific toxicity studies are required. Pivotal safety studies must comply with Good Laboratory Practice standards, and regulators expect full data tables with individual results for each animal tested, not just summaries.
Clinical Data
If the drug has already been tested in humans in earlier trials, those results belong here. This section presents any existing data on safety, dosing, and effectiveness from previous studies. For a Phase 1 trial of a completely new compound, this section may be minimal. For a drug moving into later-phase trials, it can be extensive.
Full vs. Simplified IMPD
Not every clinical trial requires the full dossier. If the drug already has marketing authorization in the EU or in a country that follows international pharmaceutical standards, sponsors can submit a simplified IMPD. In this case, much of the safety and quality information is replaced by the drug’s existing Summary of Product Characteristics, the official document that accompanies any approved medicine. The simplified version is common when researchers study a new use for an existing drug, since regulators already have detailed files on the product.
When a drug holds marketing authorization in multiple EU countries with slightly different product summaries, the sponsor must explain which version they selected and why.
Placebos get the lightest treatment. If the placebo has the same composition as the test drug (minus the active ingredient), is made by the same manufacturer, and isn’t sterile, only quality data is needed. No animal studies, no clinical summaries.
How the IMPD Fits Into Trial Approval
The IMPD is one component of a larger clinical trial application. Once submitted, the application enters a structured review process with strict timelines measured in calendar days. Due dates cannot fall on weekends or official holidays, and there is an informal pause between December 23 and January 7 each year unless the sponsor objects. For multinational trials, holiday calendars from all participating countries factor into the schedule.
A designated Qualified Person at the manufacturing site plays a critical role throughout the trial. This individual signs off that each batch of the investigational product has been manufactured and tested in line with the clinical trial authorization and current good manufacturing practices. No batch can be released for use in a trial without this certification.
Updating the IMPD During a Trial
An IMPD is not a static document. As new data emerges or manufacturing processes change, the dossier must be updated. Some changes qualify as substantial modifications, meaning they require regulatory approval before they can be implemented.
Examples of substantial modifications include switching to a different investigational product, changing the drug’s formulation, adjusting the dose level or route of administration, or submitting new toxicology or pharmacology data that shifts the risk-benefit assessment. The sponsor is responsible for deciding whether a change is substantial, using a risk-based approach, and must provide side-by-side comparisons of old and new wording along with justification for each change.
Route A substantial modifications are those likely to have a significant impact on participant safety or data reliability. Route B modifications are defined more narrowly in regulation. Both require approval before implementation, with one exception: changes related to urgent safety measures can be made immediately and reported afterward.
IMPD vs. the U.S. Equivalent
The IMPD is a European concept. In the United States, the closest equivalent is the Investigational New Drug (IND) application submitted to the FDA. The IND covers similar ground: chemistry, manufacturing, and controls; pharmacology and toxicology; and clinical protocols. The core scientific requirements overlap substantially, but the formatting, submission systems, and regulatory procedures differ. Sponsors running global trials often need to prepare documentation that satisfies both frameworks.