Hereditary angioedema (HAE) is a rare genetic disorder that causes tissue swelling that can sometimes be life threatening. HAE is caused by a deficiency or dysfunction of the C1 esterase inhibitor (C1-INH) enzyme, and abnormal C1-INH activity leads to increased levels of bradykinin, a key mediator in angioedema. Previously, the main treatment options available for HAE in the United States were androgens and fresh-frozen plasma. The FDA, however, recently approved three therapies that have been used in Western Europe for several years. The newly approved treatments include: (1) plasma-derived C1-INH concentrates used for acute attacks and short-term prophylaxis, (2) ecallantide, a kallikrein inhibitor, which is the only approved drug for children aged 12 and older, and (3) icatibant, a bradykinin receptor antagonist that can be used for self-treatment of acute attacks. Additionally, recombinant C1-INH derived from transgenic rabbits is currently awaiting FDA approval. Recombinant C1-INH may prove to be safer than plasma-derived C1-INH. While these novel therapies should help treat acute HAE, more research is needed for specific long-term prophylactic regimens.
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