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

Nephrolithiasis, also called kidney stone disease, occurs in patients with genetic susceptibility and who may have a broad spectrum of metabolic disorders and other comorbid conditions (for example obesity or diabetes). These renal stones develop as a result of supersaturation. Calcium oxalate (CaOx) is the most common type of stone. Reducing the urinary excretion of uric acid is an established approach for the treatment of CaOx kidney stones. The objective of this study is to evaluate treatment with febuxostat compared to allopurinol or placebo in the reduction of 24-hour urine uric acid (uUA) excretion levels in hyperuricosuric patients with a recent history of renal stones and the presence of at least one CaOx stone larger than or equal to 3 mm as seen on Multidetector Computed Tomographic Angiography (MDCT). Participants in this study will be required to make 4 office visits provide 3 urine samples and undergo 2 MDCT scans (a type of x-ray) of their kidneys.