From the FDA Information Sheets, Guidance for Institutional Review Boards and Clinical Investigators, 1998 Update.
FDA defines the emergency use means the use of a test article on a human subject in a life-threatening situation in which no standard acceptable treatment is available, and in which there is not sufficient time to obtain IRB approval. [21CFR 56.102(d)]
Obtaining an Emergency IND
Exemption from Prospective IRB Approval