A patient with gout has normal renal function and no history of nephrolithiasis. He is started on a uricosuric agent as monotherapy for hyperuricaemia. The drug lowers serum urate by inhibiting which transporter at the proximal tubule?

• A Sodium-glucose cotransporter 2 (SGLT2)
• B Xanthine oxidase in the intestinal mucosa
• C Na-K-2Cl cotransporter in the thick ascending limb
• D Urate anion exchanger URAT1 and organic anion transporter (OAT) ✓

Explanation

Probenecid is a uricosuric that blocks reabsorption of urate in the proximal tubule by inhibiting the URAT1 exchanger and OAT transporters, increasing urinary urate excretion and lowering serum levels. It does not touch xanthine oxidase, which is the target of allopurinol and febuxostat, so option B kills itself mechanistically. Because it floods the urine with uric acid, it is avoided in patients with a history of urate stones.

Reference: Katzung Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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