Which drug is a uricosuric agent that increases uric acid secretion and may promote uric acid stones?

• A. Allopurinol
• B. Probenecid
• C. Colchicine
• D. Febuxostat

Answer: (B)

Uricosuric agents increase uric acid elimination by blocking reabsorption in the kidney, specifically in the proximal tubule, which raises the amount of uric acid excreted in the urine. This lowers serum uric acid but can lead to uric acid stone formation because more uric acid remains in the urine, especially when urine is acidic or volumes are low. Probenecid is the classic uricosuric drug that inhibits uric acid reabsorption, boosting urinary uric acid excretion. In contrast, drugs like allopurinol and febuxostat reduce uric acid production by inhibiting xanthine oxidase, and colchicine treats inflammation without affecting uric acid excretion.