What is Firazyr used for?
Medically reviewed by Carmen Fookes, BPharm. Last updated on May 12, 2020.
- Firazyr (icatibant) may be given by subcutaneous injection to treat angioedema attacks in adults with hereditary angioedema (HAE).
- Firazyr treats an acute attack of HAE by blocking the actions of bradykinin. Bradykinin increases blood vessel permeability and is thought to be responsible for the symptoms of an acute attack of HAE.
Firazyr (icatibant) is a selective B2 bradykinin receptor antagonist indicated for the treatment of acute attacks in adults 18 years and older with hereditary angioedema (HAE).
Hereditary angioedema is a genetic disorder that causes attacks of severe swelling in the limbs, face, intestinal tract, and airway.
How does Firazyr work?
People with hereditary angioedema (HAE) have low levels of naturally occurring C1 inhibitory protein (C1-INH) in their blood. C1-INH is a key regulator of the Factor XII/kallikrein cascade that leads to the production of bradykinin. Bradykinin is thought to be responsible for the characteristic symptoms of angioedema attacks seen in HAE.
Firazyr (icatibant) blocks the bradykinin B2 receptor, to the same extent as what bradykinin would. By inhibiting the binding of bradykinin to the B2 receptor it helps treat the symptoms of an acute attack of HAE.
How is Firazyr given?
Firazyr is given by subcutaneous (under the skin) injection into the abdominal area.
The usual dosage to treat an acute attack of angioedema is 30mg. If attack symptoms persist additional doses may be administered at intervals of at least 6 hours.
No more than 3 doses may be administered in any 24 hour period.
Firazyr may be administered by a trained health professional experienced at treating HAE; however, people can also be taught how to administer it themselves.
What is hereditary angioedema?
Hereditary angioedema is a genetic disorder characterized by severe swelling in the limbs, face, intestinal tract, and airway. There are three known types: Type I and II caused by mutations in the Serping I gene and Type III which is caused by mutations in the F12 gene.
The Serping I gene provides instructions for making the C1 inhibitor protein, which helps control inflammation. Mutations in this gene can lead to either reduced levels of C1 protein in the blood or the production of a C1 inhibitor that functions abnormally. When levels of this C1 protein are decreased, excessive amounts of another protein fragment, called bradykinin are generated. Bradykinin increases the leakage of fluid through the walls of blood vessels into body tissues, promoting inflammation. This causes fluid to accumulate which causes the swelling characteristic of hereditary angioedema type I and type II.
Some cases of hereditary angioedema type III are associated with mutations in the F12 gene. This gene codes for an important protein that helps our blood to clot, known as coagulation factor XII. Factor XII is also an important stimulator of inflammation and is involved in bradykinin production. Certain F12 mutations produce Factor XII with an increased activity, which generates more bradykinin, leading to blood vessel wall leakage and angioedema. The gene mutations responsible for other types of hereditary angioedema III have not yet been discovered.
- Hereditary angioedema. Genetics home reference. https://ghr.nlm.nih.gov/condition/hereditary-angioedema#genes
- Feussner A, Kalina U, Hofmann P, Machnig T, Henkel G. Biochemical comparison of four commercially available C1 esterase inhibitor concentrate for treatment of hereditary angioedema. Transfusion. 2014;54(10):2566‐2573. doi:10.1111/trf.12678
- Firazyr (icatibant) [Package Insert] July 1, 2019 Shire US Manufacturing Inc. https://www.drugs.com/pro/firazyr.html