Cinryze: C1 inhibitor approved for prophylaxis of angioedema attacks in patients with hereditary angioedema (HAE)

This agent is a preparation of C1 inhibitor that is derived from human plasma. C1 inhibitor regulates the activation of the complement and intrinsic coagulation pathway, as well as the fibrinolytic system. This C1 inhibitor (human) preparation was approved on October 10, 2008, for routine prophylaxis against angioedema attacks in adolescent and adult patients with hereditary angioedema (HAE).

Efficacy. The efficacy of this agent was assessed in a single randomized, double-blind, placebo-controlled, multicenter, crossover study in 24 patients. Patients were randomized to treatment with C1 inhibitor (human) prophylaxis for 12 weeks followed by placebo prophylaxis for 12 weeks or placebo prophylaxis for 12 weeks followed by C1 inhibitor (human) prophylaxis. Injections were administered every 3 to 4 days and approximately 2 times per week. The efficacy outcome was based on the number of attacks recorded during the C1 inhibitor treatment period versus the number recorded during the placebo treatment period. A total of 6.1 attacks (mean) were reported during treatment with C1 inhibitor versus 12.7 attacks (mean) during treatment with placebo. The treatment effect with C1 inhibitor was statistically significant versus placebo (P<.0001). C1 inhibitor treatment was associated with significant improvements in the mean severity of HAE attacks (P=.0006 vs placebo), the mean duration of HAE attacks (P=.0023 vs placebo), and the days of swelling (P<.0001 vs placebo).

Safety. Severe hypersensitivity reactions, including hives, urticaria, tightness of the chest, wheezing, hypotension, and/or anaphylaxis, may occur among patients treated with this agent. C1 inhibitors carry a risk of transmitting infectious agents, including the Creutzfeldt-Jakob agent. The most common adverse events observed in patients treated with this agent include sinusitis, rash, headache, and upper respiratory tract infections.