A critical reappraisal of allopurinol dosing, safety, and efficacy for hyperuricemia in gout.

Allopurinol, the first-line drug for serum urate-lowering therapy in gout, is approved by the US Food and Drug Administration for a dose up to 800 mg/d and is available as a low-cost generic drug. However, the vast majority of allopurinol prescriptions are for doses < or = 300 mg/d, which often fails to adequately treat hyperuricemia in gout. This situation has been promoted by longstanding, non-evidence-based guidelines for allopurinol use calibrated to renal function (and oxypurinol levels) and designed, without proof of efficacy, to avoid allopurinol hypersensitivity syndrome. Severe allopurinol hypersensitivity reactions are not necessarily dose-dependent and do not always correlate with serum oxypurinol levels. Limiting allopurinol dosing to < or = 300 mg/d suboptimally controls hyperuricemia and fails to adequately prevent hypersensitivity reactions. However, the long-term safety of elevating allopurinol dosages in chronic kidney disease requires further study. The emergence of novel urate-lowering therapeutic options, such as febuxostat and uricase, makes timely this review of current allopurinol dosing guidelines, safety, and efficacy in gout hyperuricemia therapy, including patients with chronic kidney disease.