Study HGT-FIR-096 is a multicenter, Phase III, randomized, double-blind, two-armed, placebo-controlled trial. The study population will consist of 118 adult patients, 18 years of age or older, who present with an acute ACE-I-induced angioedema attack. The primary aim of the study is to demonstrate that icatibant is significantly more effective than placebo in resolving attacks of angioedema caused by ACE-I based on the Time to Meeting Discharge Criteria (TMDC). Safety and tolerability, as well as the pharmacokinetics (PK), of icatibant will also be evaluated. Eligible patients will be randomized at a 1:1 ratio to receive a single sub-cutaneous injection of either 30 mg icatibant or placebo.