Inclusion Criteria:

To be eligible to participate in the study, a patient must meet all of the following inclusion criteria:

• Patient is at least five years of age.
• Patient has been diagnosed with sickle cell anemia or sickle ß0-thalassemia (documented by hemoglobin electrophoresis).
• Patient has had at least two episodes of painful crises within 12 months of the screening visit.
• If the patient has been treated with an anti-sickling agent within three months of the screening visit, the therapy must have been continuous for at least three months with the intent to continue for the next 14 months.
• Patient or the patient’s legally authorized representative has given written informed consent.
• If the patient is a female of child-bearing potential, she agrees to practice a recognized form of birth control during the course of the study.

Exclusion Criteria:

If the patient meets any of the following criteria, the patient must not be enrolled:

• Patient has a significant medical condition that required hospitalization (other than sickle painful crisis) within two months of the screening visit.
• Patient has diabetes mellitus with untreated fasting blood sugar >115 mg/dL.
• Patient has prothrombin time International Normalized Ratio (INR) > 2.0.
• Patient has serum albumin < 3.0 g/dl.
• Patient has received any blood products within three weeks of the screening visit.
• Patient has a history of uncontrolled liver disease or renal insufficiency.
• Patient is pregnant or lactating.
• Patient has been treated with an experimental anti-sickling medication/treatment (except hydroxyurea) within 30 days of the screening visit.
• Patient has been treated with an experimental drug within 30 days of the screening visit.
• There are factors that would, in the judgment of the investigator, make it difficult for the patient to comply with the requirements of the study.