Hereditary angioedema (HAE) is a disorder characterized by recurrent episodes of non-allergic, severe swelling (angioedema) in the absence of urticaria or hives. Individuals experience swelling episodes that resolve within 2 to 5 days without treatment; however laryngeal swelling can be fatal. The most common areas of the body to develop swelling are the limbs, face, intestinal tract, and airway. Minor trauma or stress may trigger an attack, but swelling often occurs without a known trigger. Episodes involving the intestinal tract cause severe abdominal pain, nausea, and vomiting. Swelling in the airway can restrict breathing and lead to life-threatening obstruction of the airway.
Bradykinin is a vasodilator that results in the swelling that is associated with angioedema. Since the angioedema is non-allergic, histamines are not involved and antihistamines are not effective. HAE can also occur because of a deficiency (missing or low levels of the protein C1 esterase inhibitor [C1-INH]) or malfunction of the C1 inhibitor in the body which regulates the coagulation pathway. Lack of adequate amounts of C1-INH impacts vascular permeability, causing fluid leakage in blood vessels and capillaries.
There are three types of hereditary angioedema: type I (low C1-INH levels), accounting for roughly 85% of cases; type II (poorly functioning C1-INH levels), accounting for roughly 15% of cases; and type III (normal functioning C1-INH), considered to be very rare, occurring predominantly in women. The different types have similar signs and symptoms, but are distinguished based on the underlying causes and levels of C1-INH protein. Treatment options consist of on-demand therapy for acute HAE attacks in order to reduce the severity and duration of attacks and ongoing preventive or prophylactic therapy to prevent attacks in individuals who experience frequent or severe attacks, with dramatic lifestyle impairment. Treatment options consist of various mechanisms of action, including C1 esterase inhibitors, plasma kallikrein inhibitors and bradykinin B2 receptor antagonists.
C1 esterase Inhibitor [Human] (Berinert), C1 esterase Inhibitor [Human] (Cinryze), C1 esterase inhibitor [recombinant] (Ruconest) or ecallantide (Kalbitor) may be covered under the medical benefit; please refer to the pharmacy policies for coverage of C1 esterase Inhibitor (Haegarda), icatibant acetate (Firazyr) and lanadelumab (Takhzyro).