Self-administration of intravenous C1 esterase inhibitor in hereditary angioedema.

somal dominant disorder that results in episodes of acute edema in various organs, including the gastrointestinal tract, skin and larynx. It is estimated to affect about 1 in 50 000–100 000 people. The symptoms, including abdominal pain, laryngeal edema and subcutaneous edema, usually begin in childhood and persist throughout life with unpredictable severity. Hereditary angioedema is classified into 3 subtypes: type I, caused by a congenital deficiency of C1 esterase inhibitor (C1-INH); type II, characterized by dysfunctional C1-INH; and type III, an estrogen-dependent form with normal quantitative and functional C1-INH. C1 esterase inhibitor plays a role in the complement, fibrinolytic, clotting and kinin pathways. Without C1-INH, activation of these pathways can occur, resulting in bradykinin release and flares of edema. First-line therapy for acute episodes of type I and II hereditary angioedema is replacing the missing protein with C1-INH concentrate, which halts the progression of the clinical manifestations within 20 minutes. C1 esterase inhibitor is administered intravenously, limiting its use to in hospital, which can delay access to treatment. Self-administration of C1-INH at the first sign of an acute attack is an intuitive intervention to hasten recovery and quickly reduce symptoms, and it has the potential to decrease the number of yearly hospital admissions for affected people. Because of the rarity of hereditary angioedema, emergency department staff may not immediately recognize the symptoms of an acute attack, and patients may not be triaged appropriately. Some hospitals may not stock C1-INH, which may result in treatment delay, the need for higher doses to adequately treat the attack and, as a consequence, higher rates of hospital admissions and severe adverse events, including death. How does self-administration work?