Investigational New Drug (IND) is a term used by the Food and Drug Administration (FDA) to refer to drug substances or products that are undergoing clinical investigation to show their safety and efficacy in treating, diagnosing, or curing diseases or conditions. A drug substance or product's clinical investigation is conducted through a series of clinical trials on human subjects.

The IND process provides an external review of the proposed clinical plans, such as the clinical design, animal studies, patient population, and inclusion/exclusion criteria, as well as manufacturing information to ensure quality control. The FDA also reviews adverse event reports from the clinical trials. Once the IND process is completed, the FDA will render its final opinion on the safety and efficacy of the drug.

One of the major reasons for the existence of the IND process is to ensure that drugs that claim to have beneficial effects are monitored and tested to make sure they are effective and safe. An IND must be filed with the FDA if a company wants to conduct clinical trials in the United States. Companies that want to bring a drug to market must also file an IND before they are able to begin marketing their drug.

The IND process is an important factor in the development of any new drug and a major component of the drug development process. New indications refer to news signifying that an existing drug may have a broader range of medical applications, and further IND processes may be required to expand the drug’s label.

The IND process is time consuming and highly regulated, but it serves a very important purpose. The FDA uses the IND process to ensure new drugs are safe, effective, and high quality before they are made available to the public. While repurposing existing drugs in this manner can prove less costly than developing new drugs from scratch, the time and effort involved in the IND process can provide a significant barrier to entry for companies wishing to market existing drugs for new indications.