Background: Cetirizine and astemizole have been shown to be safe and effective in the treatment of patients with chronic idiopathic urticaria. Cetirizine brings about clinical benefit more rapidly.
Objective: The purpose of this study was to compare the efficacy of single daily doses of cetirizine and astemizole in relieving the symptoms of chronic idiopathic urticaria, with particular emphasis on the commencement of action.
Methods: Patients with chronic idiopathic urticaria were randomly assigned to relieve either 10 mg of cetirizine, 10 mg of astemizole, or placebo for 4 weeks in a multicenter double-blind trial. Patients rated symptom severity each night, and investigators rated symptoms weekly.
Results: One hundred eighty-seven patients were enrolled in the trial; 180 were included in the safety analysis and 177 were included in at least one efficacy analysis. Both cetirizine and astemizole were significantly superior to placebo in relieving symptoms of chronic idiopathic urticaria. Both patients' and investigators' ratings indicated that cetirizine acted more rapidly. Both active treatments were well tolerated, and the incidence of somnolence did not differ statistically between cetirizine (14.5%) and astemizole (10.3%).
Conclusion: Both cetirizine and astemizole provide effective relief of the symptoms of chronic idiopathic urticaria with similar side-effect profiles. However, clinical benefit occurs significantly more rapidly with cetirizine.