C1S and angioedema: Although no therapies are currently approved by the U.S. Food and Drug Administration (FDA) specifically for ACEI-induced angioedema, off-label treatments used in hereditary angioedema, such as plasma-derived C1 esterase inhibitors (C1-INH), which replace deficient enzyme activity, and icatibant, a selective bradykinin B2 receptor antagonist, have been employed [1,2,8].