Bradykinin blocker · angioedema attacks
Icatibant is a selective, competitive antagonist of the bradykinin B2 receptor: a synthetic decapeptide that contains five non-natural amino acids1. It treats sudden attacks of hereditary angioedema (HAE), a rare inherited condition that causes episodes of severe swelling in the skin, gut and airway.
In HAE, people lack enough working C1-esterase inhibitor, a protein that normally keeps the kallikrein cascade in check. Without it, the cascade overproduces bradykinin, a small peptide that widens blood vessels and is thought to cause the swelling, inflammation and pain of an attack1. Icatibant competes with bradykinin for the B2 receptor, binding with similar affinity, so bradykinin cannot deliver its signal1.
In healthy volunteers given a bradykinin challenge, it blocked the resulting drop in blood pressure, vessel widening and fast heart rate1. Because it acts at the receptor, downstream of the problem, it treats an attack in progress but does not correct the underlying C1-inhibitor deficiency.
Three randomized controlled trials in adults with HAE attacks underpin approval1. In FAST-3, 88 people with skin or abdominal attacks received icatibant or placebo; median time to a 50% drop in symptoms was 2.0 hours versus 19.8 hours, and time to first relief 0.8 versus 3.5 hours3.
In FAST-2, icatibant outperformed oral tranexamic acid (2.0 versus 12.0 hours to meaningful relief), while in FAST-1 the gap versus placebo (2.5 versus 4.6 hours) was not statistically significant, possibly because many placebo patients took early rescue medication2. Outside HAE, a randomized trial in 121 adults with airway swelling caused by ACE-inhibitor blood-pressure drugs found no benefit over placebo4, so its effect in HAE did not extend to that kind of angioedema.
FDA-approved in 2011, as Firazyr, for acute attacks of hereditary angioedema in adults 18 and older1; generic versions have been approved since 2019. The EU authorised it in 2008 and now allows its use in children over 25.
Injection-site reactions such as redness, swelling and pain occurred in almost all patients (97%) in trials1. Other reactions seen in more than 1% included fever, raised liver enzymes, dizziness and rash. Because throat attacks can block the airway, the label says people should seek emergency care after treating a laryngeal attack. The label lists no contraindications.
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