Chronic urticaria: impact of allergic inflammation

Urticaria is defined by weals (hives), with or without angioedema, that appear and peak in minutes to hours, usually disappear within 24 h, and are accompanied by pruritus that worsens during the night. Urticaria is caused by cutaneous mast cell degranulation, attributed to immunological, nonimmunological, and idiopathic causes. Chronic idiopathic urticaria (CIU) is the diagnosis when the pathophysiological mechanism of persistent urticaria remains unclear; up to half of patients with CIU have functional autoantibodies directed against the high-affinity receptor for IgE (FcepsilonRI) or against IgE itself, which appear to induce mast cell degranulation. Systemic histamine H1-receptor antagonists, such as desloratadine, are central to the management of CIU. The efficacy and safety of desloratadine, 5 mg once daily, was studied in a double-blind, randomized, placebo-controlled, multicentre trial that included 190 patients, ages 12 and above, with at least a 6-week history of CIU and experiencing a flare of at least moderate severity. Desloratadine was superior to placebo in controlling pruritus and total symptoms after the first dose, and its superiority was maintained throughout the full 6 weeks of the study. Measures of sleep, daily activity, therapeutic response, and global CIU status were also significantly improved with desloratadine after the first dose and maintained throughout the study.