IND stands for Investigational New Drug, and it refers to the formal application a drug sponsor files with the FDA before testing an experimental drug in people. It is essentially a request for permission to ship and administer a drug that has no approved marketing status yet. Without an active IND, federal law prohibits transporting an unapproved drug across state lines, which would make multi-site clinical trials impossible.
Why the IND Exists
Before any new drug can be given to a human volunteer in the United States, it must clear a basic safety threshold. The IND is the checkpoint where the FDA reviews whether the drug is reasonably safe enough for initial, limited testing in people. It sits at the boundary between lab and animal research (preclinical development) and the first human trial.
The sponsor, usually a pharmaceutical company or sometimes an individual researcher, submits the IND after screening a new molecule for biological activity and toxicity in animals. The FDA then has 30 calendar days to review the application. If the agency does not object or place the study on hold within that window, the sponsor may begin the clinical trial. The IND is not an “approval” in the way most people think of one. It is closer to a green light that says the available evidence does not suggest unreasonable risk to participants.
What Goes Into an IND Application
The application covers three broad areas:
- Animal and lab studies. Preclinical data showing the drug’s effects in animals, including toxicity results, so the FDA can judge whether the product is reasonably safe for first-in-human testing. If the drug has already been used in people in another country, that experience is included here too.
- Manufacturing information. Details about how the drug is made, what it contains, how stable it is, and what quality controls are in place. The FDA needs to confirm the company can produce consistent batches so that every participant in a trial receives the same product.
- Clinical protocols and investigator qualifications. A detailed plan for the proposed study, including how it will be designed, who will be enrolled, and what safety monitoring will look like. The physicians overseeing the trial must be qualified, and the application must include commitments to obtain informed consent from every participant and to have the study reviewed by an institutional review board.
The Pre-IND Meeting
Before filing, many sponsors request a pre-IND meeting with the FDA. This is an opportunity to get feedback on the design of preclinical studies, the manufacturing process, and the plan for the first human trial. A well-prepared pre-IND meeting helps sponsors submit a more complete application and reduces the chance the FDA will place the study on hold. Sponsors typically come to the meeting with a draft protocol, summaries of all completed animal studies, and a list of specific questions grouped by topic.
What Happens After Filing
Once the IND is active and the first trial begins, the application does not sit on a shelf. It becomes a living document that the sponsor updates throughout the entire clinical development program, from the small Phase 1 safety study through large Phase 3 trials involving thousands of patients. New study protocols, updated safety data, and manufacturing changes all get filed as amendments to the original IND.
When enough evidence of safety and effectiveness has been gathered, the sponsor submits a New Drug Application (NDA) to seek marketing approval. The NDA is the finish line. The IND is the starting gate.
Safety Reporting Under an Active IND
Sponsors have strict obligations to report serious safety problems while an IND is active. If a participant dies or experiences a life-threatening reaction that was unexpected based on what was known about the drug, the sponsor must notify the FDA within 7 calendar days. Other serious and unexpected reactions, or new findings from animal studies or data analyses suggesting significant risk, must be reported within 15 calendar days. These reports go to the FDA and to every investigator participating in any trial under that IND.
A serious adverse event, in regulatory terms, is one that results in death, hospitalization, a lasting disability, or a birth defect. It also covers events that may not check those boxes but that, in a physician’s judgment, could jeopardize the patient without medical intervention.
Clinical Holds
The FDA can pause a trial at any point by placing it on clinical hold. For a Phase 1 study, this can happen if participants would be exposed to unreasonable risk, if the investigators are not adequately qualified, if the investigator brochure is misleading or incomplete, or if the application simply does not contain enough information to assess safety. For Phase 2 and 3 studies, the FDA can also impose a hold if the study design is clearly inadequate to meet its own stated goals.
There are additional grounds for holding studies that are not designed as rigorous controlled trials. The FDA may intervene if such a study is interfering with enrollment in a well-controlled trial of the same drug, if evidence strongly suggests the drug does not work, or if another drug for the same condition offers a clearly better balance of benefit and risk.
Types of INDs
Not every IND is filed by a large company planning to bring a product to market. There are several distinct categories:
- Commercial IND. Filed by a company with the intent to eventually seek marketing approval. This is the most common type and the one that supports the standard Phase 1 through Phase 3 development path.
- Investigator IND. Filed by an individual researcher, often at a university, who both initiates and conducts the study. The investigator takes on the regulatory responsibilities that a company would normally handle.
- Expanded access (compassionate use) IND. Used to provide an unapproved drug to patients outside of a clinical trial, typically when no other treatment options exist. This comes in three sizes: single patient, intermediate-size (a smaller group), and widespread treatment use. For a single patient, the FDA offers a simplified form to reduce paperwork.
- Emergency use IND. Allows a physician to use an investigational drug in an urgent, life-threatening situation before a full IND can be submitted. The FDA can authorize emergency use by phone, and the physician files the formal paperwork afterward.
When an IND Is Not Required
Some clinical research on drugs that are already on the market does not need an IND. A study using a marketed drug is generally exempt if it meets all of these conditions: the drug is lawfully sold in the U.S., the study is not intended to support a new approved use or a major labeling change, it does not involve a route of administration, dose, or patient population that significantly increases risk, and the study still complies with institutional review board requirements and informed consent rules. In practice, this exemption covers many investigator-initiated studies in academic medical centers where a physician is studying an already-approved drug at its standard dose for a purpose closely related to its existing use.