Icatibant

Icatibant (Firazyr) — Bradykinin B2 Receptor Antagonist

Evidence & Status

  • FDA Approved
  • Strong Human Evidence
  • Strong

At a Glance

An FDA-approved synthetic peptide that selectively blocks bradykinin B2 receptors to treat acute hereditary angioedema attacks in U.S. adults 18 years of age and older. It blocks bradykinin-mediated swelling; laryngeal attacks still require immediate medical evaluation.

Plain English

Icatibant blocks the receptor that bradykinin uses to cause swelling during hereditary angioedema attacks. This is its established, approved use in U.S. adults. It also helps explain the broader kallikrein-kinin system and why ACE inhibitors can sometimes cause angioedema through bradykinin accumulation. Icatibant is being studied and used off-label for ACE-inhibitor angioedema, but randomized trials have produced conflicting results, so that use is not an established indication.

Overview

Icatibant is a synthetic decapeptide and selective competitive antagonist of the bradykinin B2 receptor (B2R). In hereditary angioedema (HAE) caused by C1-inhibitor deficiency or dysfunction, excess bradykinin signaling increases vascular permeability and drives swelling. Acute HAE attacks may affect the skin, gastrointestinal tract, face, or larynx; laryngeal attacks can threaten the airway. By blocking B2 receptors, icatibant interrupts this established pathway and is used for acute HAE attacks. FIRAZYR is approved in the United States for acute HAE attacks in adults 18 years of age and older, with self-administration for appropriate patients. ACE-inhibitor angioedema remains an off-label research question with conflicting randomized evidence, not an established indication.

Research Summary

In the Phase III randomized, double-blind, placebo-controlled FAST-3 trial of cutaneous or abdominal HAE attacks, median time to at least 50% reduction in symptom severity was 2.0 hours with icatibant versus 19.8 hours with placebo (P < 0.001). Median time to almost complete symptom relief was 8.0 hours versus 36.0 hours, respectively (P = 0.012). These findings support strong randomized human evidence for acute HAE treatment. ACE-inhibitor angioedema has a bradykinin-based rationale, but randomized evidence is conflicting: one smaller randomized trial reported median complete-resolution time of 8.0 hours with icatibant versus 27.1 hours with comparator treatment (P = 0.002), while a later larger randomized placebo-controlled trial found median time to discharge criteria of 4.0 hours with icatibant versus 4.0 hours with placebo (P = 0.63). Efficacy for ACE-inhibitor angioedema is therefore not established.

Research Areas

  • Hereditary angioedema
  • Bradykinin B2 receptor pharmacology
  • Kallikrein-kinin system
  • ACE inhibitor angioedema
  • Vascular permeability
  • Inflammatory mediators

Safety & Risks

Serious Risks

  • Laryngeal HAE attacks require immediate medical evaluation and monitoring after FIRAZYR treatment because airway obstruction can still progress
  • Theoretical cardiovascular risk — weigh the potential benefit against theoretical risk in acute coronary ischemia, unstable angina, or during the weeks following stroke

Reported Side Effects

  • Injection-site reactions
  • Pyrexia
  • Elevated transaminases
  • Dizziness
  • Rash
United States
FIRAZYR is FDA-approved for treatment of acute attacks of hereditary angioedema (HAE) in adults 18 years of age and older; appropriate patients may self-administer
United Kingdom
EMA-approved for HAE attacks; prescription only; first approved in Europe (2008)
Australia
TGA-approved for HAE attacks; prescription only
Canada
Health Canada-approved for HAE; prescription only

Citations & Sources