Comparative effects of loratadine and terfenadine in the treatment of chronic idiopathic urticaria.

Loratadine is a new selective peripheral histamine H1-receptor antagonist, that is orally effective, long-acting, and devoid of significant central and autonomic nervous system activity. Its safety and efficacy were evaluated in a 28-day study conducted in patients with chronic idiopathic urticaria. Patients were randomly assigned to one of three treatment groups (loratadine, 10 mg OD; terfenadine, 60 mg BID; or placebo). Evaluation of efficacy included weekly assessments of the individual disease signs and symptoms, the overall disease condition, and therapeutic response to treatment. Throughout the 28-day treatment period progressive improvement was observed in the loratadine and terfenadine treatment groups; however, at each evaluation, loratadine was significantly more effective than placebo (P less than .01) and clinically more effective than terfenadine in reducing disease signs and symptoms. Terfenadine was significantly more effective than placebo at day 7 and endpoint (last valid visit). The overall therapeutic response at the endpoint of treatment was rated as marked or complete relief of symptoms in 64%, 52%, and 25% of the patients in the loratadine, terfenadine, and placebo treatment groups, respectively. Loratadine was well tolerated and comparable to terfenadine and placebo in incidence of adverse experiences. Sedation was reported in one patient each in the terfenadine and placebo treatment groups and an anticholinergic side effect (dry mouth) in one terfenadine-treated patient. No sedative or anticholinergic side effects were observed in patients receiving loratadine. We concluded that loratadine, 10 mg, once daily is a safe and effective treatment for symptomatic relief of chronic idiopathic urticaria.