RESUMO
OBJECTIVE: Desloratadine is a potent antihistamine. Whether regular or on-demand use of desloratadine influences its therapeutic efficacy in allergic rhinitis is unknown. The aim of the study was to compare the clinical efficacy and the anti-inflammatory activity of regularly administered desloratadine to its on-demand use in children with allergic rhinitis due to pollen allergy. METHODS: Thirty-seven patients with allergic rhinitis with or without mild intermittent asthma were enrolled in a prospective parallel group study. Patients were treated with desloratadine regularly or on-demand during pollen season. Rescue medications and symptom scores were recorded on a diary card. Nasal flow rate and inflammatory markers were recorded, and methacholine (Mch) challenge test was administered before and within the pollen season. RESULTS: Though symptoms were lower in the evening than in the morning (p<0.001), there was no difference between the two groups. There was no difference between the groups with respect to medication score except that the salbutamol use was lower in the regular treatment group during the fourth week (p=0.032) in the pollen season. Nasal flow rate and inflammatory markers failed to show any difference between the groups. A significant reduction in PC20 values (provocative concentration of Mch causing a 20% fall in FEV(1)) was observed in regular (p=0.016) and on-demand (p=0.005) treatment groups compared to the pre-season measurements. The number of children with a PC20 below 8 mg/ml increased significantly in the on-demand group. CONCLUSION: Our study demonstrates that on-demand use of desloratadine during the pollen season is clinically as effective as regular treatment. However, regular treatment may provide better control of lower airway symptoms and airway reactivity.