What Is an Investigational New Drug Application

By Kevin Fernando · Sep 29, 2026 · 9 min read

An Investigational New Drug (IND) application is the regulatory permission a drug sponsor must obtain from the FDA before testing a new drug in humans. It exempts the sponsor from the federal requirement that drugs be approved before distribution across state lines, and it allows the FDA to review preclinical data and study protocols before human trials begin.

An Investigational New Drug (IND) application is the regulatory permission a drug sponsor must obtain from the FDA before testing a new drug in humans. It is not approval to market the drug, nor is it a guarantee that the drug will prove safe or effective. Instead, it is the legal mechanism that allows a sponsor to ship an investigational drug across state lines to clinical investigators and to begin human testing after the FDA has reviewed preclinical data and the proposed study design.

The IND sits at a specific moment in drug development: after a molecule has been screened for activity and toxicity in animals, but before any human is exposed to it. Understanding what an IND is, when it is required, what information the FDA demands, and how the agency reviews it helps researchers, analysts, and others reading drug development filings make sense of where a drug candidate stands in its path to market.

What an Investigational New Drug application actually is

An Investigational New Drug application is the means through which a drug sponsor obtains an exemption from the FDA requirement that drugs be approved before being transported or distributed across state lines. It is a regulatory filing, not a clinical decision or a scientific judgment. The FDA's role in IND development begins when a drug sponsor, having screened a new molecule for pharmacological activity and acute toxicity potential in animals, wants to test its diagnostic or therapeutic potential in humans.

The IND serves two purposes at once. First, it is the legal mechanism that permits the sponsor to move the drug across state lines to reach clinical investigators in multiple locations. Second, it is the vehicle through which the FDA reviews whether the preclinical evidence supports exposing humans to the drug, and whether the proposed human study is designed in a way that protects participant safety. The FDA does not approve or disapprove an IND in the traditional sense; instead, it either raises concerns that must be addressed or allows the study to proceed after 30 days.

When a drug requires an IND application

An IND is required for any clinical investigation involving administration of a drug to humans, unless the study is exempt. The exemption categories are narrow and specific. For marketed drugs, an investigation is exempt from IND requirements if it is not intended to be reported to FDA as a well-controlled study in support of a new indication for use nor intended to be used to support any other significant change in the labeling for the drug. Exempt categories include serological tests, placebos, bioavailability and bioequivalence studies, and radioactive drugs for research use.

For a new drug candidate entering human testing for the first time, an IND is almost always required. The requirement applies regardless of whether the drug is being developed by a large pharmaceutical company, a small biotech firm, an academic medical center, or any other entity. It applies to any drug intended for human use, whether the indication is treatment of disease or diagnosis of disease. The scope of the IND requirement is broad; the exemptions are exceptions to that rule.

What the FDA requires in an IND submission

An IND application is a comprehensive document that packages three categories of information: chemistry and manufacturing data, preclinical safety results, and the proposed clinical protocol along with information about the investigators who will conduct the study. The FDA uses these three components to assess whether the sponsor has done adequate homework before asking humans to take the drug, and whether the proposed study is designed to protect participants while generating useful data.

The specific information required depends on the drug class, route of administration, planned indication, and planned duration of treatment. A sponsor developing an oral tablet for chronic use will submit different data than a sponsor developing an intravenous agent for acute use. The FDA's guidance documents and regulations specify what must be included, but the principle is consistent: the FDA needs enough information to understand what the drug is, how it will be made consistently, what it does in animals, and how humans will be exposed to it.

Chemistry, manufacturing, and controls information

The Chemistry, Manufacturing, and Control (CMC) component of an IND application includes information for the drug substance, the drug product, placebo formulation if applicable, labeling information for labeled products relevant to the investigational drug, and an environmental analysis. This section outlines how the sponsor will ensure the proper identification, quality, purity, stability, and strength of the drug candidate and explains the intended manufacturing method and process.

The CMC section answers practical questions: What is the chemical composition of the drug? How will it be synthesized or extracted? How will the sponsor test each batch to confirm it meets specifications? How long will the drug remain stable under various storage conditions? If the drug will be given as a tablet or capsule, what are the inactive ingredients, and how will they be combined? The FDA uses this information to verify that the sponsor can manufacture the drug consistently and that what is given to the first human participant will be chemically identical to what is given to the last.

Pharmacology and toxicology data

A complete IND application includes data documenting the results of comprehensive preclinical safety assessments. The kind, duration, and scope of animal and other studies required in an IND application depends on the duration and nature of the proposed clinical investigations. Key IND-enabling studies typically required include pharmacology, pharmacokinetics, and toxicology assessments.

Pharmacology studies show what the drug does to the body: Does it bind to the intended target? Does it produce the expected biological effect in animal models? Pharmacokinetics studies show what the body does to the drug: How quickly is it absorbed? How is it distributed to tissues? How is it metabolized and eliminated? Toxicology studies show what harm the drug might cause: At what dose do adverse effects appear in animals? Do those effects reverse when dosing stops? Are there any signs of damage to organs or systems? The FDA reviews these data to determine whether the proposed starting dose in humans is reasonable and whether the study design includes adequate monitoring for potential harms.

Clinical protocol and investigator information

An IND application must include the proposed clinical protocol, which describes in detail what will be done to study participants, how many participants will be enrolled, what safety monitoring will occur, and how the data will be analyzed. The application must also include information about the qualifications of the investigators who will conduct the study, demonstrating that they have the training and experience to safely administer an investigational drug and to recognize and manage adverse events.

The protocol specifies the study phase, the participant population, the dosing schedule, the duration of exposure, and the endpoints that will be measured. It describes what safety assessments will be performed and how often. It explains the informed consent process and what information participants will receive about the risks and benefits of participation. The FDA reviews the protocol to confirm that it is scientifically sound, that it poses no unreasonable risks to participants, and that the investigators are qualified to conduct it safely.

How the FDA reviews an IND application

The FDA's review of an IND application follows a defined timeline and process. The agency has 30 calendar days to review an initial IND application. During this window, the FDA's review division assesses the three components of the submission: the chemistry and manufacturing data, the preclinical safety results, and the clinical protocol. The FDA also verifies that the sponsor has received institutional review board (IRB) review and approval of a clinical investigation in accordance with FDA regulations.

After the 30-day period, the IND goes into effect unless the FDA notifies the sponsor that investigations are subject to a clinical hold or provides earlier notification that investigations may begin. This means the sponsor may begin enrolling participants and administering the investigational drug. The FDA does not typically send a letter notifying the sponsor of approval; instead, the absence of a clinical hold notification means the IND is active.

The 30-day review period

During the 30-day review window, the FDA's review team examines the IND application. Sponsors can secure full Institutional Review Board (IRB) approval for a protocol during the 30-day IND evaluation timeframe, but must still allow the FDA review window to elapse before commencing clinical trials. This means that while IRB approval and FDA review can happen in parallel, human dosing cannot begin until the 30 days have passed and no clinical hold has been issued. The 30-day review period begins when the FDA receives the application.

When the FDA raises concerns

If the FDA identifies deficiencies or safety concerns during its review, it may issue a clinical hold, which prevents the sponsor from beginning the study. A clinical hold is issued when the FDA believes that human participants would be exposed to unreasonable risk, or when the application is incomplete or does not contain adequate information to assess safety and scientific validity.

Common reasons for a clinical hold include inadequate preclinical toxicology data, concerns about the proposed starting dose, inadequate safety monitoring in the protocol, or questions about investigator qualifications. When the FDA issues a clinical hold, it provides the sponsor with a detailed explanation of the deficiencies. The sponsor must then address each concern, resubmit the application, and the FDA begins a new review cycle. This process continues until the FDA's concerns are resolved and the IND can proceed.

What happens after an IND is approved

Once an IND goes into effect, the sponsor may begin enrolling participants in the clinical trial. All clinical trials must operate under an active Investigational New Drug application. The typical clinical trial pathway includes three phases. Phase 1 trials are concerned primarily with establishing a new drug's safety and dose range in about 20 to 100 healthy volunteers. Approximately 70 percent of drugs move from Phase 1 to the next phase.

Phase 2 studies determine the effectiveness of an experimental drug on a particular disease or condition in approximately 100 to 300 volunteers and may last from several months to two years. Phase 3 studies are larger and longer trials in the clinical trial process. A company must first complete three phases in the clinical trial process before it can submit its experimental drug to the FDA for approval to sell. After all three phases are complete and the data are analyzed, the sponsor submits a New Drug Application (NDA) or Biologics License Application (BLA) for final FDA approval to market the drug.

Common misconceptions about INDs

The IND application is often misunderstood because its name suggests approval, and because its role in the regulatory pathway is sometimes conflated with later stages. Two misconceptions are especially common and worth clarifying.

An IND is not approval to market the drug

An IND permits human testing to begin; it does not permit the drug to be sold. The distinction is critical. An IND is a research authorization; a New Drug Application (NDA) or Biologics License Application (BLA) is a marketing authorization. The IND allows the sponsor to gather safety and efficacy data from human participants. Only after all clinical trial phases are complete, the data are analyzed, and the sponsor submits an NDA or BLA does the FDA make a decision about whether the drug may be marketed for a specific indication.

A drug can have an active IND for years while clinical trials are ongoing, and it may never reach the market if the trials show it is not safe or effective. Conversely, a drug cannot be marketed without first having had an IND that permitted the clinical trials that generated the evidence for marketing approval. The IND is a necessary step on the path to marketing, but it is not itself marketing approval.

An IND does not guarantee the drug is safe

IND approval means the preclinical data support human testing and the proposed study is designed to protect participants; it does not mean the drug will prove safe or effective in humans. The FDA's decision to allow an IND to proceed is based on the evidence available at that moment, which is animal data and in vitro studies. Animal models do not always predict human response. A drug that appears safe in animals may cause unexpected adverse effects in humans. A drug that shows promise in animal models may prove ineffective or harmful in clinical trials.

The purpose of the clinical trial phases is to test the drug in humans and gather evidence about its actual safety and efficacy. The IND is the permission to begin that testing under controlled conditions with informed participants and robust safety monitoring. It is not a prediction of the outcome. Many drugs with active INDs fail to demonstrate safety or efficacy and never advance to later trial phases or to marketing approval.

Do this automatically

Compiling the chemistry and manufacturing data, preclinical safety results, and clinical protocol information required for an IND submission demands weeks of specialized work across multiple departments, with each component requiring careful review and revision before submission to the FDA. Software systems can automate the organization, formatting, and cross-referencing of these complex data packages to accelerate the assembly process. Healthcare research reads ClinicalTrials.gov records, regulatory filings, and published literature directly, and cites each claim to the record it came from, across as many subjects as you need, with Mimir attaching a citation to every figure. It will not predict a trial's outcome or advise on anyone's treatment. Those decisions stay with clinicians and regulators, and deliberately so. Every plan includes it, including the free one.

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This article is general information about healthcare and life-sciences topics. It is not medical advice, diagnosis, or treatment guidance, and it is not a substitute for a qualified professional. Any treatment decision should be discussed with a clinician.