- Patients must have either (a) normal kidney function (i.e. creatinine =< 1.5 X upper limit of normal [ULN] OR calculated creatinine clearance >= 60 mL/min by the modified Cockcroft and Gault Formula OR a creatinine clearance >= 60 mL/min obtained from a 24-hour urine collection) or (b) moderate or severe renal dysfunction (i.e. creatinine clearance < 60 mL/min and >= 20 mL/min)