Inclusion Criteria:

- Patients with homozygous sickle cell (Hb SS) confirmed by hemoglobin electrophoresis
or HPLC

- Patients with adequate cardiac, renal, and liver function

- Patients with baseline fetal hemoglobin (Hb F) level of 10% or less

- Patients with at least 6% dense cells or higher at initial screening visit

- Patients with no history of coronary heart disease

- Patients with normal baseline ECG

- Patients with no history of hypotension or hypotensive episodes

Exclusion Criteria:

- Patients who are pregnant, trying to become pregnant, or breast feeding

- Patients who are on a chronic transfusion program

- Patients who are unable to take oral medications

- Patients who have significant cardiac, renal, or liver dysfunction

- Patients who are on hydroxyurea

- Patients who have a fetal hemoglobin (Hgb F) level of greater than 10%, or have less
than 6% dense cell on initial screen

- Patients who are taking a supplement which contains magnesium

- Patients who are taking aspirin, ibuprofen on a daily basis, or anti-coagulant such
as Coumadin on a daily basis

- Patients who have a known underlying coagulopathy (acquired or congenital) or have
prolonged PT or PTT at the time of initial screen

- Patients who have had a hypersensitivity to either of the study medications

- Patients who are taking any other study medication(s). Patients will not be excluded
if they are on penicillin prophylaxis or folic acid, or use ibuprofen intermittently

- Patients taking tetracycline or sodium polystyrene sulfonate

- Patients on concomitant medications and other therapy must have a wash out period
prior to study entry and/or study drug dosing

- Patients with abnormal baseline ECG

- Patients with a history of hypotension or hypotensive episodes