KLK4 and angioedema: Bradykinin-mediated forms of angioedema are typically resistant to therapies effective in histamine-mediated reactions.1,4,7,8,13,135,136,147 At the time of construction for this review, several medications have been FDA approved for treatment of acute bradykinin-mediated angioedema: three C1-INH concentrates (two plasma-derived and one recombinant), one kallikrein inhibitor, and one bradykinin-2-receptor antagonist (Table 3).1,4,7,8,13,135,136