Progress in the emergency management of hereditary angioedema: focus on new treatment options in the United States

Hereditary angioedema (HAE) is a rare disorder generally caused by a deficit in the activity of C1-esterase inhibitor (C1-INH). Symptoms manifest as recurrent episodes of nonallergic, nonpruritic, and nonpitting edema. Attacks commonly occur on the extremities, trunk, genitalia, abdomen, or head and neck–the latter 2 locations are associated with the greatest morbidity and mortality. In the United States, there has been a considerable void in effective HAE treatments and emergency management guidelines. Clinical outcomes using agents such as fresh-frozen plasma, attenuated androgens (danazol), or plasmin inhibitors (aminocaproic acid) have not been ideal. Recent years have seen progress with US Food and Drug Administration (FDA) approval of several products for acute HAE treatment. Plasma concentrate of C1-INH has long been the treatment of choice in many parts of the world, and a pasteurized formula received FDA approval in October 2009 for treating attacks. Ecallantide, a plasma kallikrein inhibitor, and icatibant, a bradykinin receptor antagonist, were approved in December 2009 and August 2011, respectively, for treatment of acute attacks. A recombinant C1-INH product is in late development stages for treating acute attacks. These new treatments provide symptom relief within hours, dramatically shorten attack duration, and decrease mortality from airway compromise. For the first time, US physicians have rapid-acting and highly effective treatments for managing acute HAE attacks.