Role of Inflammatory Mediators in AERD

Inclusion Criteria: * History of asthma * History of nasal polyposis * History of at least one clinical reaction to oral aspirin or other nonselective COX inhibitor with features of both lower (cough, chest tightness, wheezing, dyspnea) and upper (rhinorrhea, sneezing, nasal obstruction, conjunctival itching and discharge) airway involvement * Stable asthma (post-bronchodilator FEV1 of ≥70%, no use of oral or systemic steroids for at least 1 month, and no hospitalizations or emergency room visits for asthma for the prior 6 months) at the time of entry into the study * Currently taking montelukast as part of standard asthma treatment for at least 4 weeks before the V1 visit Exclusion criteria: * Pregnancy or current breastfeeding * History of bleeding diathesis or use of anticoagulant or antiplatelet drugs * History of thrombocytopenia \< 50 x 10\^9/L * Hypersensitivity to montelukast * Peptic ulcer disease * Unstable asthma (post-bronchodilator FEV1 of less than 70%, use of oral or systemic steroids for at least 1 month prior to visit 1, or hospitalizations or emergency room visits for asthma for the prior 6 months) * Use of zileuton (which can mask symptoms of aspirin-induced reaction) within 1 month prior to the V1 visit * Age under 18 or over 75 years * Current smoking