Suspected Unexpected Serious Adverse Reaction(SUSAR)
A serious adverse event suspected to be related to the investigational product that is not expected based on the current Investigator's Brochure.
Usage Examples
- A fatal SUSAR was reported within 7 calendar days to FDA and all applicable regulatory authorities.
- Recurring SUSARs of the same organ toxicity triggered an Investigator's Brochure safety update.
What is SUSAR?
A SUSAR is a specific category of serious adverse event in clinical trials that meets three criteria: serious (per ICH E2A definition), suspected to be causally related to the investigational product (by investigator or sponsor), and unexpected — meaning the event's nature, severity, or outcome is not consistent with the risk information in the current Investigator's Brochure. SUSARs drive expedited safety reporting.
US regulations (21 CFR 312.32) require IND safety reports within 15 calendar days for SUSARs and within 7 calendar days for fatal or life-threatening SUSARs. EU Clinical Trials Regulation and ICH E2A align on 15/7-day timelines for EudraVigilance reporting. SUSAR reports must include case narrative, seriousness and causality assessment, outcome, and any concomitant medications. Patterns across SUSARs feed into signal detection and may drive Investigator's Brochure updates, protocol amendments, or clinical hold orders.
Regulatory Context
This term appears most often in pharmacovigilance workflows where submission quality, regulatory evidence, and audit readiness depend on consistent language. It is commonly referenced alongside ICH E2A, 21 CFR 312 32, EU CTR 536 2014.
When This Matters
- A fatal SUSAR was reported within 7 calendar days to FDA and all applicable regulatory authorities.
- Recurring SUSARs of the same organ toxicity triggered an Investigator's Brochure safety update.
Common Mistakes
- Treating safety signal reviews as periodic instead of continuous.
- Not linking new enforcement letters to internal CAPA and labeling workflows.
- Using static templates for dynamic benefit-risk communication updates.
Related Regulations
Frequently Asked Questions
All three criteria must be met: (1) serious per ICH E2A, (2) suspected related to investigational product by investigator or sponsor, (3) unexpected — not consistent with current IB risk information. Meeting only two criteria makes it a different reportable category, not a SUSAR.
No. Fatal or life-threatening SUSARs require reporting within 7 calendar days. All other SUSARs require reporting within 15 calendar days. The clock starts at the day the sponsor becomes aware of the event meeting SUSAR criteria.
The term SUSAR is specific to investigational products in clinical trials. Post-approval equivalents have different naming — "serious unexpected adverse drug reactions" in postmarket contexts — with different reporting timelines under 21 CFR 314.80 for drugs and equivalent EU/ICH frameworks.
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