Factors Involved in Dymista's Superior Clinical Efficacy in the Treatment of Seasonal Allergic Rhinitis

Dymista, a combined product containing the antihistamine azelastine and the intranasal steroid fluticasone, provides superior clinical efficacy to both fluticasone propionate and azelastine hydrochloride in the treatment of seasonal allergic rhinitis. The superiority of efficacy not only occurs at the initiation of treatment, but persists for its duration. The mechanism underlying the superior efficacy of Dymista is not known. This trial focuses on examining the effects of Dymista on the dynamics of the allergic response in man using nasal provocation with antigen. The investigators will study the relationship between symptoms, physiology, cells and mediators.

The main hypothesis for the trial is that Dymista affects multiple phases of the allergic response, which in sum are greater than the effects of fluticasone propionate or azelastine hydrochloride alone. Our objectives for this study are to demonstrate: 1. that the induction of allergic inflammation by nasal provocation with antigen causes a cellular infiltration, with subsequent release of inflammatory biomarkers that cause augmented responses to subsequent exposure to antigens. 2. that fluticasone prevents allergic inflammation from developing after antigen challenge and subsequently prevents the augmentation of the nasal response to nasal challenge with antigen. 3. that the azelastine in Dymista reduces the effects of released histamine To address these hypotheses we will perform a 3-way, randomized, placebo-controlled, and crossover trial. We will recruit 20 asymptomatic seasonal allergic rhinitis patients outside of the relevant season. The subjects will receive placebo, fluticasone propionate and Dymista. The nasal provocations will be separated by 2 weeks. Treatment will begin 15 minutes before nasal provocation with ragweed or grass antigen and the treatment will continue twice a day for 3 days. Nasal provocation will occur daily for three days to evaluate for priming (increased sensitization with repeated antigen exposure, which mimics seasonal disease where antigen exposure occurs in the setting of continued allergic inflammation). For outcome measures, we will monitor both nasal symptoms after nasal provocation as well as collect nasal lavage to evaluate effects on eosinophils and biomarkers of the immune response. In the nasal lavage, we will quantify the number of eosinophils (a marker of cellular recruitment) and measure the levels of histamine (a marker of basophil and mast cell activation), tryptase (a marker of mast cell activation), albumin (a marker of vascular permeability), lactoferrin (a marker of glandular activation) and ECP (a marker of eosinophil activation). Thus we expect to generate information on both clinical effects and physiologic differences between the treatments.