Icatibant

Firazyr

Icatibant is a synthetic decapeptide built largely from non-natural amino acids, a design that makes it resistant to enzymatic degradation and stable enough for a simple subcutaneous injection. Its function is to block the bradykinin B2 receptor. Bradykinin is a potent signaling peptide that increases the leakiness of blood vessels; when it is overproduced, fluid escapes into tissues and causes swelling (angioedema). By competitively blocking the B2 receptor, icatibant stops bradykinin from driving this vascular leak and halts the swelling of an acute attack. Its approved use is the treatment of acute attacks of hereditary angioedema (HAE) in adults. HAE is a rare genetic disorder — most often caused by deficiency or dysfunction of C1 esterase inhibitor — in which uncontrolled bradykinin production triggers recurrent, unpredictable episodes of severe swelling of the skin, abdomen, and airway. Airway attacks can be life-threatening. Because HAE swelling is bradykinin-mediated rather than histamine-mediated, ordinary allergy treatments such as antihistamines, corticosteroids, and epinephrine do not work — which is exactly why a targeted bradykinin blocker is so valuable. A major practical advantage of icatibant is that it is designed for subcutaneous self-administration: patients (or caregivers) can inject it into the abdomen at the first sign of an attack, at home, without needing intravenous access or refrigeration in the same way as some other HAE therapies. It was approved by the FDA in 2011 (Firazyr). The most common side effect is a transient local injection-site reaction — redness, swelling, and pain — which is expected and usually resolves within hours. It is a prescription medicine used within an HAE management plan supervised by a specialist.