(1) The reference prophylaxis of attacks of hereditary angioneurotic oedema is oral danazol, an androgenic steroid, which takes a few days to act. There was previously no curative treatment authorised in France. (2) C1 esterase inhibitor is now licensed in France as replacement therapy for patients with hereditary angioneurotic oedema due to a quantitative or qualitative deficiency in this protein. (3) The clinical evaluation file partly answers the practical questions that arise in this setting, but it does not include trials versus danazol. (4) In 36 patients with acute attacks of angioneurotic oedema, a double-blind trial showed that symptom relief was achieved in less than half an hour in 69% of attacks treated with C1 esterase inhibitor, compared to only 2% of attacks treated with placebo. (5) In the prophylactic setting, a crossover trial involving six patients refractory to conventional androgen therapy showed that injections of C1 esterase inhibitor every three days were more effective than a placebo in reducing the risk of attacks. (6) No major adverse effects have been attributed so far to C1 esterase inhibitor, but the fact that the drug is derived from human blood means that treatment carries a theoretical risk of infection by conventional infectious agents (especially nude viruses) and prions. (7) In practice, for life-threatening attacks of angioneurotic oedema, C1 esterase inhibitor is rapidly effective in two-thirds of patients and is now the reference treatment. In the absence of comparative trials, danazol remains the first-line prophylaxis when patients are scheduled for surgery a few days later, but C1 esterase inhibitor is useful when danazol is ineffective. C1 esterase inhibitor is the only available prophylaxis for patients undergoing emergency surgery (within a few hours).
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