What is an IND? It is an Investigational New Drug application: the filing a sponsor sends to the FDA before a new drug is tested in people. It is the safety-and-study file that opens the door to a clinical trial. It does not put the drug on pharmacy shelves, prove that it works, or create an ordinary prescription route.
The letters describe an application, not a medicine. People often call a drug "an IND," but the precise wording is that the drug is being studied under an IND.
What is an IND in FDA rules?
Title 21, Part 312 of the federal regulations defines an investigational new drug as a new drug or biologic used in a clinical investigation. A clinical investigation is an experiment involving one or more people, apart from ordinary medical use of a marketed drug.
That sounds formal because the rule has to cover a wide range of research. A first-in-human study may be testing whether exposure is reasonably safe. A later study may compare outcomes in hundreds or thousands of people. The same Part 312 framework follows the drug across those stages.
The sponsor is the person or organization responsible for the study. It can be a drug company, university, government agency, nonprofit, or an individual physician who both sponsors and conducts the work.
Why the IND system exists
The modern gate grew out of the 1962 Kefauver-Harris Amendments. FDA's history of the law explains that the amendments required evidence of safety and effectiveness before marketing, informed consent from trial participants, details about drug distribution and clinical studies, and earlier animal work to support safety.
The point is simple: people shouldn't be the first safety check. Before an investigational drug reaches them, FDA gets a chance to examine the proposed study, the product and the evidence supporting that first step.
What goes into an IND application?
The FDA's IND overview groups the contents into three practical buckets:
- Nonclinical evidence: laboratory and animal findings that help FDA judge whether the proposed human exposure is reasonably safe.
- Manufacturing information: what the drug is, how it is made, and how identity, strength, quality, purity and stability are controlled.
- The human study plan: the protocol, meaning the written plan for who can enroll, what will happen, what will be measured and how risk will be watched. FDA also receives information about the investigators, informed consent and review by an institutional review board, an independent group that protects study participants.
An IND is therefore much more than a form with a molecule's name on it. It connects one product, one sponsor and one or more specific research protocols.
The 30-day IND review window
Under 21 CFR 312.40, an IND generally goes into effect 30 days after FDA receives it. A study may begin sooner if FDA sends earlier notice that it may proceed. FDA can also place the study on clinical hold, meaning the proposed research must pause while a safety or other serious deficiency is addressed.
This is why "FDA allowed the trial to proceed" is more accurate than saying the agency endorsed the drug. The decision is about whether a defined investigation may start, not whether the product may be marketed.
How an IND shows up in peptide medicine
Retatrutide is a clean example. It is an investigational peptide, so its U.S. human studies use the IND pathway. One randomized phase 2 obesity study enrolled 338 adults (Jastreboff et al., New England Journal of Medicine, 2023). A separate phase 2 study enrolled 281 adults with type 2 diabetes (Rosenstock et al., The Lancet, 2023). Those papers describe selected participants following fixed protocols with study oversight. They do not describe ordinary prescriptions.
The narrow route for receiving retatrutide outside a trial is still an investigational route. The site's guide to retatrutide early access explains how a treating doctor, the manufacturer and FDA each have a role in a single-patient request. It is not a retail shortcut.
Compounding is different. A routine compounded prescription is patient care, not a clinical trial, and dispensing it does not place the patient under an IND. Through Promise, tirzepatide and semaglutide are dispensed as compounded medications, which are different from FDA-approved products: the formulations offered here are not FDA-approved. That product-status distinction does not turn the prescription into research.
BPC-157 makes the same point from another direction. A compounded BPC-157 prescription does not become an experiment under an IND simply because the finished product has no U.S. marketing application. An IND needs a sponsor, a protocol and research oversight; a prescription alone supplies none of those things.
Regulatory status is one input into care. For a compounded formulation that can lawfully be prescribed, a licensed provider may still prescribe it; that decision is between the patient and the doctor. At Promise, a licensed provider reviews every request, and not everyone qualifies.
Mistakes people make about IND meaning
"The drug passed FDA review." The study was allowed to proceed under a defined plan. That is not the same decision as permission to market the product.
"Everyone receiving the molecule is part of the trial." Trial participation requires enrollment, consent and a research protocol. A normal prescription is not quiet or informal enrollment.
"Compounded means experimental." Compounded products are not premarket-reviewed like manufactured products, but pharmacy compounding and clinical investigation are separate legal pathways. One does not create the other.
"An IND belongs to a peptide forever." It belongs to a sponsor's development program and covered protocols. Other sponsors may file their own applications for the same active ingredient or a different formulation.
IND vs NDA vs ANDA
These three abbreviations answer different questions. FDA's application guide draws the line clearly.
| Filing | The plain question it asks | What it can lead to |
|---|---|---|
| IND | May this human investigation begin? | A clinical trial that is allowed to proceed |
| NDA | Does the full evidence support marketing this new drug for a stated use? | Permission to market if the application succeeds |
| ANDA | Does this proposed generic, rather than a new drug, match its reference product as required? | Permission to market if the application succeeds |
A compounded preparation is not a generic: it does not use another company's ANDA and does not inherit that application's status. FDA tentative approval is another distinct term for an application that has cleared scientific review but still faces a legal barrier to marketing.
What changed in September 2026
As of September 18, 2026, the day this article was written, the definition and the usual 30-day clock had not changed, but FDA had launched an Expedited IND Pilot on September 15. The pilot pairs selected sponsors with qualified research institutions and allows parts of an application to be reviewed on a rolling basis before submission. FDA said it expected to choose 8 to 10 pairs and would keep full authority over whether a study may proceed or be held.
That is an effort to improve preparation and timing. It is not a separate route around Part 312 and does not turn an IND into marketing permission.
Related terms
The 503A bulks list concerns which source ingredients may fit one patient-specific compounding route. FDA Category 2 is an interim compounding-policy category for nominated bulk substances with identified safety concerns. Neither is an IND list, a clinical-trial roster or a drug application.
Keeping those lanes separate makes the regulatory language much less mysterious: IND is for investigation, NDA is for a new marketed drug, ANDA is for a proposed generic rather than a new drug, and Sections 503A and 503B govern pharmacy compounding under their own conditions.
