Febuxostat Versus Allopurinol or Placebo in Patients With Hyperuricosuria and Calcium Oxalate Stones

Inclusion Criteria: * Has hyperuricosuria, defined as a daily urine uric acid excretion greater than 700 mg as measured by 24-hour urine collection prior to randomization. * Has at least one calcium oxalate stone greater than or equal to 3 mm in its longest in-plane diameter, identified by Multiple Detector Computated Tomography prior to randomization. * Has a recent (within the previous 5 years) history of renal stones prior to screening. Exclusion Criteria: * Has gout, secondary hyperuricemia or has experienced a gout flare. * Has a history of xanthinuria. * Has received allopurinol or probenecid within 2 years prior to randomization. * Has received febuxostat. * Has alanine aminotransferase and/or aspartate aminotransferase values greater than 2.0 times the upper limit of normal at the Screening Visit. * Has an abnormal serum calcium level at the Screening Visit. * Has a significant medical condition and/or conditions that would interfere with the treatment, safety or compliance with the protocol according to the judgment of the Investigator. * Has a history of drug abuse or a history of alcohol abuse within 5 years prior to the Screening Visit. * Participant's measured creatinine clearance is less than 30 mL/min at the Screening Visit. * Has hypercalciuria at Screening, while on a regular unrestricted diet, defined as urinary excretion of: * greater than 250 mg of calcium/24-hour for females of body weight less than 62.5 kg; OR * greater than 300 mg calcium/24-hou…