 Inflammatory arthritis in patients with gout is caused by crystals of monosodium urate MSU that form as a result of chronically elevated levels of uric acid in plasma and extracellular fluids. Recurrent attacks can usually be prevented by treatment with drugs that block urate synthesis by inhibiting xanthine oxidase, or that promote uric acid excretion. If for various reasons noncompliance, drug intolerance, inadequate dosage, or inefficacy therapy fails to maintain serum urate concentration below about 6 mgdL, gout can progress to a chronic stage characterized by destructive arthropathy, deposition of urate crystals in soft tissues tophi, and nephropathy. The management of chronic gout in such patients is often complicated by co-morbidities such as hypertension, heart disease, diabetes, and renal insufficiency, which may limit the use of anti-inflammatory agents to treat arthritis. 