Phase 2 Study of Montelukast for the Treatment of Sickle Cell Anemia

Inclusion Criteria: * 1)Diagnosis of HbSS, or HbSβ-thalassemia0, confirmed by hemoglobin analysis * 2)Males and females age 16 years to 70 years old * 3)Greater than 2 episodes of pain in the last 12 months * 4)On a stable dose of hydroxyurea for at least 2 months and a stable hemoglobin Exclusion Criteria: 1. Judged not likely to be study compliant by his/her hematologist 2. History of adverse reaction to montelukast or any of the components of montelukast 3. Have used medications known to interact with montelukast such as rifampin, phenobarbital, and gemfibrozil within 4 weeks of enrollment 4. Currently being treated with a leukotriene antagonist (montelukast or zileuton) or have used montelukast/zileuton within the last 60 days 5. Chronic blood transfusion therapy defined as regularly scheduled transfusions. 6. Hemoglobin A greater than15% on hemoglobin analysis 7. Individuals with a current physician diagnosis of asthma (within last 12 months) or requires continuous supplemental oxygen, or predicted or current use of asthma medications (inhaled corticosteroids, but participants taking bronchodilators will be allowed to participate). 8. Current participation in another therapeutic trial for SCD 9. Known current pregnancy 10. Known history of HIV 11. Serum creatinine greater than 3 times the site's upper limit of normal