Hereditary angioedema (HAE) resulting from the deficiency of the C1 inhibitor 
protein is a rare disease, characterized by paroxysms of edema formation in the 
subcutis and in the submucosa. Edema can cause obstruction of the upper airway, 
which may lead to suffocation. Prompt elimination of edema is necessary to save 
patients from this life-threatening condition. Essentially, these edematous 
attacks are related to the activation of the kinin-kallikrein system and the 
consequent release of bradykinin. Ecallantide (known as DX-88 previously), a 
potent and specific inhibitor of plasma kallikrein is an innovative medicinal 
product. This is the only agent approved recently by the FDA for all 
localizations of edematous HAE attacks. Its advantages include no risk of viral 
contamination, high selectivity, very rapid onset of action, good tolerability, 
and straightforward subcutaneous administration. Owing to the risk of 
anaphylaxis, ecallantide should be administered by a health care professional. A 
postmarketing survey to improve risk-assessment and risk-minimization has been 
launched. The results of these studies may lead to the approval of ecallantide 
for self-administration.