1. To administer multiple doses of an intravenous formulation of busulfan (Bu) at a dose adjusted to yield a blood drug level with a median daily area under the plasma concentration curve (AUC) of approximately 6,500 µMol-min. This dose will be given intravenously over three hours once daily for four (4) days, in combination with Fludarabine at a dose of 40 mg/m2 as preparation for bone marrow or peripheral stern cell transplantation in patients with acute myeloid leukemia or myelodysplastic syndromes.