Background: Cetirizine, an H1-receptor antagonist, has been studied for the relief of seasonal and perennial allergic rhinitis, one of the most common allergic disorders in the United States. Unlike newer antihistamines that can have interactions with other medications, including some macrolide antibiotics and some antifungal agents, cetirizine has not been associated with adverse events consequent to interaction with drugs that depend on hepatic enzymes for their metabolism.
Objective: The efficacy of cetirizine was compared with that of previous pharmacologic therapy in patients with allergic rhinitis. Patients were allowed to dose-titrate to achieve the optimal therapeutic response.
Method: This was a dose-ranging, open-label, multicenter, 2-week clinical trial of 296 patients with allergic rhinitis. All patients were initially treated with 5 mg of cetirizine and allowed to dose-titrate up to 20 mg/d, depending on symptom severity.
Results: Symptom severity scores decreased sharply within the first 24 hours of cetirizine therapy and continued to improve. Symptoms showing the greatest immediate improvement were rhinorrhea, itching nose, sneezing, itching eyes, and watery eyes, with nasal congestion and postnasal drip improving more slowly. By study completion, 13.4% of patients remained on the initial cetirizine dose of 5 mg/d, 31.1% increased dosage to 10 mg/d, and 41.6% increased their dose to 15 or 20 mg/d. According to physician global evaluations, 82% of patients showed improvement on cetirizine, while 75% of patients indicated that cetirizine was better than or equal to previous single-agent therapy, including those who had previously used terfenadine (75%), astemizole (80%), or other antihistamines (73%), and by 58% on previous therapy with antihistamine-decongestant combination drugs. Side effects were minimal and no different from those observed in other studies of cetirizine.
Conclusion: Dose titration of cetirizine may allow for greater efficacy and quality of life, especially for patients with refractory symptoms of allergic rhinitis in whom therapy with single-dose antihistamines has failed.