Probenecid lowers serum urate in intercritical gout by which mechanism, and why is it withheld during an acute gouty attack?
- A Inhibits xanthine oxidase; withheld because it raises urate acutely
- B Inhibits the URAT1 transporter in the proximal tubule, increasing urate excretion; initiation during an acute flare can worsen or prolong the attack due to shifting serum urate levels ✓
- C Converts urate to allantoin; withheld because it causes nephrolithiasis
- D Inhibits tubular reabsorption of urate by blocking OAT1; withheld because it precipitates renal failure
Correct answer: B. Inhibits the URAT1 transporter in the proximal tubule, increasing urate excretion; initiation during an acute flare can worsen or prolong the attack due to shifting serum urate levels
Explanation
Probenecid is a uricosuric that blocks reabsorption of uric acid via the URAT1 anion exchanger in the proximal tubule, increasing urinary urate excretion. Like allopurinol and febuxostat, it is started only after the acute attack settles, because abrupt changes in serum urate mobilise tophaceous stores and can trigger or extend flares. Option A describes allopurinol, option C describes recombinant uricase, and probenecid does not cause renal failure.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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