Safety and efficacy of C1 esterase inhibitor for acute attacks in children with hereditary angioedema

Background Human plasma‐derived nanofiltered C1 esterase inhibitor (C1 INH ‐nf) is used to treat acute angioedema attacks in patients with hereditary angioedema ( HAE ), but data regarding use in children are sparse. Methods Patients 2 to <12 years of age, body weight ≥10 kg, with a diagnosis of HAE type I or II , were recruited for a multicenter open‐label trial. Patients were recruited into 2 weight categories (10–25 kg, >25 kg). Each weight category included 2 dosing levels: C1 INH ‐nf (500 units [U], 1000 U) and C1 INH ‐nf (1000 U, 1500 U), respectively. Patients experiencing an angioedema attack were given a single intravenous dose. Primary efficacy end‐point was the onset of unequivocal relief of the defining symptom within 4 h following initiation of C1 INH ‐nf treatment. Results Nine children were treated: 3 (10–25 kg) received 500 U; 3 (>25 kg) received 1000 U; and 3 (>25 kg) received 1500 U. The lower weight/higher dose category (10–25 kg, 1000 U) was not successfully enrolled. All patients completed the study. Most angioedema attacks (n = 5) were abdominal. All patients met the primary end‐point; median time to unequivocal symptom relief was 0.5 (range: 0.25–2.5) h. Doses of C1 INH ‐nf ranged from 20.8 to 51.9 U/kg. Conclusions Treatment of a single angioedema attack with C1 INH ‐nf doses of 500 U (in patients 10–25 kg), 1000 U, and 1500 U (in patients >25 kg) were well tolerated. Doses of C1 INH ‐nf <1000 U may be appropriate in some pediatric patients.