C1 inhibitor deficiency is a rare, potentially lethal condition that can be either inherited (hereditary angioedema, HAE) or acquired (acquired angioedema, AAE). Substitutive therapy with C1-INH concentrate is the treatment of choice for severe acute attacks of angioedema in Europe.

We report the need and effect of C1-INH concentrate in 448 patients with HAE and 25 with AAE. Time to beginning of resolution of attacks, side effects were recorded.

We recorded 326 infusions of C1 inhibitor plasma concentrate in 127 HAE patients (mean infusion/patient 2.5, range 1-17) and 89 infusion in 8 AAE patients (mean infusion/patient 11.1, range 1-27). Dose of concentrate ranged from 500U to 2000U for HAE, 1000U-12000U for AAE. Time to beginning of resolution was 1 hour in 303 (93%), between 1 and 2 hours in 7 and between 2 and 12 hours in the remaining 16 patients. One HAE patient underwent tracheostomy for laryngeal edema despite treatment with C1-INH concentrate. In 5 patients with AAE (54 infusions) beginning of resolution was always within one hour; in the remaining 3 patients (35 infusions) the response became progressively slow 3 (3 hours or more) requiring higher doses of C1-INH concentrate. One anaphylactic reaction and 2 generalized cutaneous reactions were reported in 2 patients with HAE. Transmission of HCV has been recorded before introduction of virucidal methods.

C1 inhibitor concentrate is effective and safe for treatment of severe symptoms in the majority of patients with HAE. Patients with AAE may become resistant to the treatment.