The following is a summary of “Efficacy of human C1 esterase inhibitor concentrate for treatment of ACE-inhibitor induced angioedema,” published in the December 2022 issue of Emergency Medicine by Strassen, et al.

The upper aerodigestive tract is the main region of the body affected by ACE inhibitor (ACEi), causing angioedema. Antihistamines and glucocorticoids continued to have a poor therapeutic response because bradykinin mediated ACEi-induced angioedema. C1-esterase inhibitor (C1INH) is an effective and recognized therapy for bradykinin-mediated hereditary angioedema. For a study, researchers sought to assess C1INH’s therapeutic value in treating ACEi-induced angioedema.

Between December 2013 and September 2018, they conducted a double-blind, parallel-group, multicenter randomized, placebo-controlled experiment. Adults with ACEi-induced angioedema and airway obstruction qualified. Along with normal therapy (i.v. 500 mg prednisolone and 2.68 mg clemastine), participants were randomly assigned to receive single doses of either C1INH (20 IU/kg) or a placebo (0.9% NaCl) intravenously. Composite symptom ratings were evaluated after discharge and one-week following discharge, as well as at baseline and up to 48 hours. The doctor determined the time to complete edema resolution (TCER) and time to onset of relief (TOR).

Around 30 individuals were dosed and randomly assigned (16 C1INH, 14 placebo). 25 people (9 C1INH, 12 placebo) finished the experiment. TCER was 17.29 h ±10.40 h in the placebo arm and 29.63 h±15.56 h in the C1INH arm (P = 0.0457). TORs for C1INH and placebo were 4.13 h ± 3.38 h and 2.86 h ± 1.29 h for C1INH and placebo, respectively (P = 0.4443). There were no side effects associated with the trial drug.

When compared to placebo, C1INH was less effective in treating ACEi-induced angioedema in terms of time to full symptom resolution than baseline use of steroids and antihistamines.