Hereditary angioedema (HAE) manifests as intermittent, painful attacks of 
submucosal oedema affecting the larynx, gastrointestinal tract or limbs. 
Currently, acute treatment is available in Europe but not USA, and requires 
intravenous administration of a pooled blood product. HAE is most likely caused 
by dysinhibition of the contact cascade, resulting in overproduction of 
bradykinin. DX-88 (ecallantide, Dyax Corp.) is a highly specific recombinant 
plasma kallikrein inhibitor that halts the production of bradykinin and can be 
dosed subcutaneously. In a placebo-controlled Phase II trial in patients with 
HAE, DX-88 resulted in significant improvement in symptoms compared with 
placebo. A Phase III trial is ongoing. This review explains the pathophysiology 
of HAE and the mechanism by which DX-88, a non-intravenous, nonplasma-derived 
therapy, might improve the disease, and discusses the clinical course of HAE and 
available treatments. Finally, it explores the potential value and efficacy of 
DX-88 in treating HAE.