An adverse reaction, the nature or severity of which is not consistent with the applicable product information, is known as what?

• A. Trial Site
• B. Vulnerable Subject
• C. Unexpected Adverse Drug Reaction
• D. Well-being (of the trial subjects)

Answer: (C)

An unexpected adverse drug reaction is defined as an adverse event whose nature or severity is not consistent with the applicable product information for the trial drug, such as the current investigator’s brochure and labeling. When a reaction falls outside what is described in those documents, it is considered unexpected and must be reported to the sponsor and regulatory authorities within required timelines. The other terms don’t describe a reaction or its reporting: the trial site is just the study location, vulnerable subject refers to participant protections, and well-being of the trial subjects is a general consideration, not a specific ADR classification.