An IND, or Investigational New Drug application, is a formal request that allows a company or researcher to begin testing an experimental drug in humans. Under U.S. federal law, no new drug can be shipped across state lines without an approved marketing application. The IND serves as an exemption from that rule, giving the sponsor legal permission to distribute an unapproved drug to clinical trial sites across the country while the FDA monitors it for safety.
Why an IND Exists
Before a drug ever reaches a pharmacy shelf, it has to go through years of human testing. But there’s a legal catch: federal law prohibits transporting unapproved drugs across state lines. Since clinical trials almost always involve multiple research sites in different states, the sponsor (typically a pharmaceutical company, but sometimes an individual researcher) needs the FDA’s permission to ship the drug to those locations. That permission comes in the form of an IND.
The IND also marks a significant legal shift for the drug itself. Once a company identifies a promising molecule and wants to move from animal studies to human testing, that molecule officially becomes a “new drug” under the Federal Food, Drug, and Cosmetic Act. From that point forward, it’s subject to the full regulatory framework, including safety monitoring, manufacturing standards, and structured clinical trial phases.
What Goes Into the Application
An IND application has to convince the FDA that it’s reasonably safe to start testing the drug in people. The application covers three broad areas.
First, the sponsor must provide data from animal studies showing how the drug behaves in a living system: how it’s absorbed, what it does at various doses, and what toxic effects appeared. This gives the FDA a baseline for predicting how the drug might act in humans and what risks to watch for.
Second, the application includes detailed manufacturing information. The FDA needs to know exactly what’s in the drug, how it’s made, and whether the production process can reliably deliver a consistent product. This section covers the drug substance itself, the finished product (tablet, injection, etc.), any placebo formulations, and labeling. If there are differences between the version used in animal studies and the version planned for human trials, those differences must be explained along with any additional risks they might introduce.
Third, the sponsor submits clinical protocols describing exactly how the human trials will be conducted: who will participate, what doses will be given, what outcomes will be measured, and how participant safety will be protected.
The 30-Day Review Window
After the FDA receives an IND, the sponsor must wait 30 calendar days before starting any clinical trials. During that window, the FDA reviews the application specifically to make sure the proposed study won’t expose volunteers to unreasonable risk. If the agency has no objections, the trial can begin once those 30 days pass. In some cases, the FDA may clear the application earlier, letting the sponsor start sooner.
If the FDA does have serious concerns, it can issue what’s called a clinical hold, which pauses the trial before it starts (or stops one already underway). A clinical hold might happen because the animal data revealed a safety signal the sponsor didn’t adequately address, the trial design doesn’t protect participants, or the manufacturing process raises quality concerns. The sponsor can’t proceed until the issues are resolved to the FDA’s satisfaction.
The Pre-IND Meeting
Before formally filing an IND, sponsors can request a meeting with FDA staff to discuss their development plan. These pre-IND meetings are optional but can save significant time and money. The goal is to identify unnecessary studies before they’re conducted, make sure the required studies are designed to produce useful data, and flag potential clinical hold issues early. Sponsors can also discuss whether their drug might qualify for expedited pathways like Fast Track Designation or Orphan Drug Designation, which can speed up the overall development timeline.
Safety Reporting After Approval
Getting the IND approved isn’t the end of the sponsor’s obligations. Once human trials begin, the sponsor is legally required to report safety problems on strict timelines. If a serious and unexpected adverse reaction occurs during a trial, the sponsor must notify both the FDA and every investigator participating in the study within 15 calendar days. For reactions that are fatal or life-threatening, the timeline tightens to just 7 days from when the sponsor first learns of the event.
These reporting rules apply not just to events observed in the sponsor’s own trials but to safety signals from any source, including studies conducted by other researchers or reports from other countries. The system is designed so that everyone involved in testing the drug has the most current safety picture at all times.
Expanded Access and Emergency Use
An IND can also serve a different purpose entirely: giving seriously ill patients access to an experimental drug outside of a clinical trial. This pathway, sometimes called compassionate use, applies when a patient has a serious or life-threatening condition, no comparable approved treatment exists, and enrolling in a clinical trial isn’t possible. The potential benefit of the drug must justify its risks, and providing it to the patient can’t interfere with the ongoing clinical trials needed for eventual approval.
It’s worth noting that drugs accessed this way haven’t been found safe and effective by the FDA. They may not work, and they may cause unexpected serious side effects. But for patients who have exhausted all other options, expanded access provides a regulated path to try an investigational treatment. Emergency requests can be made to the FDA around the clock, including nights and weekends through the agency’s Emergency Call Center.
Who Files an IND
Most INDs are filed by pharmaceutical or biotech companies planning to develop a drug commercially. These commercial INDs support the full journey from early safety studies through the large-scale trials needed for eventual marketing approval. But individual researchers at universities or medical centers can also file what’s known as an investigator IND, typically to study an already-available drug for a new use or in a new patient population. In either case, the person or organization filing the IND takes on the legal responsibilities of a sponsor, including safety reporting and compliance with manufacturing standards.
The IND remains active for as long as clinical development continues. Sponsors submit annual reports updating the FDA on trial progress, safety data, and any changes to manufacturing. If development succeeds, the IND eventually supports a formal application for marketing approval, which is the final step before a drug can be prescribed to the general public.