A double-blind comparative study of loratadine and astemizole in chronic idiopathic urticaria

Loratadine is a long-acting, orally effective, second-generation histamine H1-receptor antagonist with proven efficacy in the treatment of chronic idiopathic urticaria. It has an excellent safety profile, and is free of undesirable side-effects such as sedation and dry mouth which often accompany the use of the classic antihistamines. In the present 28-day study, loratadine was compared with astemizole, another second-generation H1 antihistamine, for the treatment of chronic idiopathic urticaria in 110 patients (99 valid). Patients with moderate to severe pruritus and dermal lesions due to urticaria were randomly assigned to receive either loratadine (10 mg once daily) or astemizole (10 mg once daily). Both loratadine and astemizole were found to be effective in relieving the symptoms of urticaria for the duration of the study. Symptom scores were reduced by roughly 50% in both treatment groups. The efficacy of the two antihistamines was statistically comparable as determined by scoring of urticaria symptoms, therapeutic response, and global evaluation of anti-itching effect. Furthermore, the incidence of adverse events related to treatment was low and was statistically comparable between the two treatment groups. However, inasmuch as three astemizole patients experienced severe sedation, the safety profile favored loratadine.