The Investigational New Drug application represents the regulatory gateway to human clinical trials in the United States, providing the FDA with information necessary to evaluate whether proposed studies are reasonably safe for initial administration to humans. Before any clinical investigation of a new drug can begin, federal law requires that an IND be in effect, establishing a regulatory framework that protects trial participants while enabling the development of promising new therapies.

The IND submission must contain three principal categories of information. The Chemistry, Manufacturing, and Controls section describes the drug substance and drug product, including composition, manufacturing process, stability data, and quality controls. The Pharmacology and Toxicology section presents preclinical studies demonstrating that the drug is reasonably safe for initial human testing at the proposed doses. The Clinical section includes the protocol for initial human studies, qualifications of investigators, and the Investigator's Brochure summarizing all available information about the drug.

The FDA review process operates under a 30-day review clock, during which the agency evaluates whether the proposed studies expose subjects to unreasonable risk. If no clinical hold is issued during this period, the sponsor may proceed with the proposed studies. The IND remains in effect throughout clinical development, with sponsors required to submit protocol amendments before initiating new studies, safety reports when significant adverse events occur, annual reports summarizing development progress, and information amendments providing new chemistry or pharmacology data. This ongoing communication ensures continued regulatory oversight as development progresses.