J Allergy Clin Immunol 131 (6): 1491 - 1493, 2013. doi: 10.1016 / j. jaci.2013.03.034 Treatment For acute attacks, C1 inhibitor, ecallantide, icatibant For acute attacks, the following are considered first-line treatment: Purified plasma-derived human C1 inhibitor Recombinant C1 inhibitor obtained from the milk of transgenic rabbits Ecallantide (a recombinant protein that acts as a reversible inhibitor of kallikrein) Icatibant (a synthetic decapeptide that acts as a reversible, competitive antagonist of the bradykinin type 2 receptor) Recombinant C1 inhibitor has similar protease inhibitory activity but a shorter half-life than plasma-derived C1 inhibitor (1).