Comparison of the effects of desloratadine 5‐mg daily and placebo on nasal airflow and seasonal allergic rhinitis symptoms induced by grass pollen exposure

Background: Nasal congestion is a chronic symptom of seasonal allergic rhinitis (SAR) that is often difficult to treat with antihistamines. Desloratadine, a new, potent, H1‐receptor antagonist has been shown to decrease nasal congestion in clinical trials and to maintain nasal airflow in response to grass pollen exposure. We compared the effects of desloratadine 5 mg and placebo on nasal airflow, nasal secretion weights and SAR symptoms, including nasal congestion, in patients exposed to grass pollen in an environmental exposure unit. Methods: Forty‐six grass pollen allergic SAR patients received desloratadine or placebo for 7 days, followed by a 10‐day washout, and then crossed over to the other treatment for 7 days. A 6‐h allergen exposure was performed at the end of each treatment period. Results: Desloratadine was significantly superior to placebo in maintaining nasal airflow (P≤ 0.014) and lessening the increase in nasal secretion weights (P