uricosurics

Uricosurics are a class of drugs that promote the renal excretion of uric acid to lower serum urate levels. They are used to treat hyperuricemia and gout in patients who predominantly underexcrete urate rather than overproduce it. The mechanism typically involves inhibition of uric acid reabsorption in the proximal tubule, mainly through blockade of the URAT1 transporter, which increases uric acid clearance by the kidneys. Classic agents include probenecid and sulfinpyrazone; newer URAT1 inhibitors have been developed to provide a similar uricosuric effect, often used in combination with other gout therapies.

Clinical use and limitations: Uricosurics are most effective in patients with preserved renal function and a predominantly underexcretory pattern of hyperuricemia. They are less effective when uric acid overproduction is the primary issue. They may be added to xanthine oxidase inhibitors to achieve target serum urate levels. Adequate hydration is recommended, and urine alkalinization may be used to reduce the risk of uric acid stone formation. They are relatively contraindicated in significant renal impairment or a history of nephrolithiasis, since increased urinary uric acid can promote stone formation and, in some cases, worsen renal function.

Adverse effects and interactions: Common concerns include gastrointestinal upset and rare hypersensitivity reactions. A notable risk is uric acid nephrolithiasis. Drug interactions arise because uricosurics can affect the renal handling of other medications, including penicillins, methotrexate, and certain nonsteroidal anti-inflammatory drugs, necessitating monitoring and dose adjustments.

Examples: Probenecid and sulfinpyrazone are traditional uricosurics; benzbromarone has been withdrawn in some markets due to hepatotoxicity concerns. Newer agents, such as URAT1 inhibitors, are used in combination therapies to achieve sustained urate lowering.