• Time to resolution of angioedema, as defined as the time interval between when the participant first noted the onset of symptoms and when there is no objective evidence of angioedema by physical examination [ Time Frame: Measured at follow-up visit 7 days following resolution of angioedema ] [ Designated as safety issue: No ]
  

• Length of hospital stay, admission to the intensive care unit, requirement for intubation, duration of intubation, use of steroids, use of histamine receptor type 1 (H1) and H2 blockers, use of epinephrine, and blood pressure levels [ Time Frame: Measured at follow-up visit 7 days following resolution of angioedema ] [ Designated as safety issue: No ]
  

People who take ACE inhibitors may develop angioedema, a condition that causes itchy and painful swelling beneath the skin around the eyes, lips, tongue, throat, hands, or feet. In severe cases, the throat may swell, obstructing the airway and leading to breathing difficulty. ACE inhibitors prevent the breakdown of a natural chemical in the body called bradykinin. Increased levels of bradykinin, which can cause swelling, may contribute to the development of angioedema. Blocking bradykinin receptor cells prevents bradykinin from initiating swelling and may lead to a possible decrease in angioedema symptoms. The purpose of this study is to evaluate the effectiveness of HOE-140, a bradykinin receptor blocker, at reducing symptoms in people with ACE inhibitor-associated angioedema.

This study will enroll people admitted to the emergency room or hospital who have a severe case of ACE inhibitor-associated angioedema. Participants will be randomly assigned to receive an injection of either HOE-140 or placebo. Initially, participants will undergo an electrocardiogram to measure the electrical activity of the heart. Then blood pressure measurements, blood collection, a physical exam to determine the extent and duration of swelling, and photographs of the swelling will occur at 2, 4, 8, 16, and 24 hours following the start of treatment. Questionnaires will be completed by study staff and participants to assess changes in angioedema symptoms and the extent of swelling. Participants will remain in the hospital for 24 to 48 hours, depending on the severity of their symptoms. Blood will be collected at a follow-up visit that will occur 7 days after the resolution of angioedema symptoms.

Inclusion Criteria:

• Ambulatory
• ACE inhibitor-associated angioedema, as defined as swelling of the lips, pharynx, or face while taking an ACE inhibitor, no history of angioedema while not taking an ACE inhibitor, and no evidence of abnormal C1 inhibitor concentration or abnormal complement levels. People with possible cases of ACE inhibitor-associated bowel edema will not be enrolled.
• If female, must be postmenopausal for at least 1 year prior to study entry, undergone surgical sterilization, or willing to use an effective form of birth control and take a pregnancy test daily for the duration of the study

Exclusion Criteria:

• Pregnant or breastfeeding
• Started taking birth control pills in the 6 months prior to study entry