The Investigator's Brochure serves as the comprehensive reference document providing investigators with essential information about the investigational product under study. This compilation includes available physical, chemical, pharmaceutical, and biological data; preclinical pharmacology, toxicology, pharmacokinetic, and metabolic information; and all available clinical data including pharmacology, efficacy, and safety information from previous human studies. The IB enables investigators to understand the rationale for the trial and to make informed decisions about participant care.

The IB must contain sufficient information to support the proposed clinical investigation and to provide investigators with the information they need to conduct the trial safely and in accordance with the protocol. Key sections include a summary of the product's characteristics, physical and chemical properties, nonclinical study summaries, effects in humans from any prior clinical experience, guidance for investigators on recognizing and managing potential adverse reactions, and references to published literature.

Sponsors are responsible for keeping the IB current throughout the development program. As new information becomes available from ongoing studies, the IB must be reviewed and updated at least annually, though more frequent updates may be necessary when significant new safety or efficacy information emerges. Updated IBs must be provided to investigators and to IRBs/IECs, and new information may trigger the need for protocol amendments or updated informed consent processes to ensure that participants are aware of relevant new findings.