9. Creatinine clearance: The standard Cockcroft and Gault formula or the measured glomerular filtration rate (GFR) using the appropriate radiolabeled method (51-CrEDTA or Tc99m-DTPA) must be used to calculate CrCl for enrollment or dosing. The same method used at baseline should be used throughout the study. No dosage adjustment is needed in patients with CrCl >/= 45 mL/min.