Firazyr (Icatibant Injection)

Firazyr (icatibant injection) is a treatment for acute angioedema attacks in patients with hereditary angioedema (HAE). It also may be used to treat angioedema attacks caused by certain medications. It is a treatment that patients can administer themselves when they feel the first signs of an angioedema attack. 

The U.S. Food and Drug Administration approved Firazyr in 2011 for use in adult HAE patients with C1-esterase-inhibitor deficiency. The European Commission approved the treatment for these patients in 2008. In 2017, it extended its use to children ages 2 and older with HAE and C1-esterase-inhibitor deficiency.

Shire, which is now part of Takeda Pharmaceuticals, developed Firazyr. A generic form of Firazyr also is available in the U.S. from Fresenius Kabi.

How does Firazyr work?

There are three types of HAE. They are all caused by the deficiency or dysfunction of certain proteins in the blood. People with type 1 and 2 HAE have too little of a protein called C1 inhibitor. Insufficient amounts of this protein cause the body to make too much bradykinin.

Bradykinin is a protein that plays a role in the swelling process. It causes blood vessels to dilate and become more permeable, which allows fluid to leak and accumulate in tissues.

Firazyr is a selective bradykinin B2 receptor antagonist, meaning that it blocks the receptors that bradykinin normally binds to so it cannot cause the painful and potentially serious swelling attacks that mark this disease.

Firazyr in clinical trials

Icatibant, the active ingredient in Firazyr, went through several Phase 3 clinical trials (NCT02584959, NCT00097695, NCT00912093, NCT00500656) to evaluate its safety and effectiveness in treating angioedema attacks in HAE patients. Results of these studies suggested that icatibant is a safe and effective treatment for acute attacks.

Researchers also investigated the safety, tolerability, and effectiveness of self-administered Firazyr in Phase 4 and Phase 3 clinical trials (NCT01457430 and NCT00997204, respectively). A 2012 study that included trial results found self-administration of Firazyr to be safe and effective. In the Phase 4 trial, it reported a median time of 2.6 hours for a 50% reduction in symptom severity.

Icatibant also completed Phase 2 (NCT01154361) and Phase 3 (NCT01919801) clinical trials evaluating it as a treatment for angioedema attacks induced by angiotensin-converting enzyme (ACE) inhibitors. Results suggest that icatibant treatment is beneficial in treating these attacks.

A more recent and open-label Phase 3 clinical trial (NCT01386658) evaluated the safety, efficacy, and pharmacokinetics (movement in the body) of icatibant in 32 children, ages 2 to 17 with HAE and C1-esterase-inhibitor deficiency. Results showed that children tolerated a single under-the-skin dose of icatibant (0.4 mg/kg; maximum 30 mg) well and that the treatment provided “rapid” symptom relief at this dose.

Ongoing clinical trials

An observational clinical trial (NCT01034969) is recruiting patients with HAE, ACE inhibitor-induced angioedema, non-histaminergic idiopathic angioedema, or acquired angioedema, and receiving Firazyr. This survey study will document clinical outcomes over time, with data included in a Firazyr patient registry. It opened in 2009 and researchers expect to conclude it in May 2023.


Last updated: Jan. 5, 2021


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