The Effect of Ramatroban (BAY u 3405), a Thromboxane A 2 Receptor Antagonist, on Nasal Cavity Volume and Minimum Cross-Sectional Area and Nasal Mucosal Hemodynamics after Nasal Mucosal Allergen Challenge in Patients with Perennial Allergic Rhinitis

The thromboxane A 2 receptor antagonist, ramatroban (BAY u 3405), was orally administered for 4 weeks at a daily dose of 150 mg (b.i.d.) to 10 patients with perennial allergic rhinitis who had a positive reaction to house dust challenge on nasal mucosa. Nasal cavity volume and minimum cross-sectional area were measured, and changes in nasal mucosal swelling were determined following allergen challenge with house dust. The influence on nasal mucosal hemodynamics was also investigated. Nasal cavity volume and minimum cross-sectional area were measured by acoustic rhinometry, and blood flow in the nasal mucosa was measured by laser Doppler flowmetry. Percent changes in values from baseline nasal cavity volume were significantly decreased by allergen challenge before ramatroban administration, but no significant decrease was noted after ramatroban administration. Similarly, percent changes in values from baseline nasal cavity minimum cross-sectional area were significantly decreased by allergen challenge before administration of ramatroban, but not after administration. Percent changes in values from baseline nasal mucosal hemodynamics were significantly increased by allergen challenge both before and after ramatroban administration, which thus had no effect on mucosal hemodynamics. These findings suggest that ramatroban might inhibit the increase in nasal mucosal swelling but has no effect on nasal mucosal hemodynamics.