In this multicenter , double-blind , double-dummy , randomized phase 2 study , we assigned patients who had ACE-inhibitor-induced angioedema of the upper aerodigestive tract to treatment with 30 mg of subcutaneous icatibant , a selective bradykinin B2 receptor antagonist , or to the current off-label standard therapy consisting of intravenous prednisolone ( 500 mg ) plus clemastine ( 2 mg ) .