**Question:** Which of the following increases uric acid excretion

A. Allopurinol
B. Colchicine
C. Furosemide
D. Indomethacin

**Core Concept:** Uric acid is a waste product formed during the breakdown of purine-rich foods, such as red meat and seafood, and is excreted via the kidneys. Elevated uric acid levels can lead to gout and renal stones.

**Why the Correct Answer is Right:** Allopurinol is an inhibitor of xanthine oxidase, an enzyme involved in uric acid synthesis. By reducing xanthine oxidase activity, allopurinol decreases the production of uric acid. As a result, the excretion of uric acid increases, thereby lowering its blood levels and preventing gout and renal stone formation.

**Why Each Wrong Option is Incorrect:**

B. Colchicine is a medication used to treat gout and familial Mediterranean fever, primarily targeting inflammation and cell division, rather than uric acid synthesis or excretion. Its effect on uric acid levels is minimal and not the primary mechanism of action in treating gout.

C. Furosemide is a loop diuretic, which promotes the excretion of water, sodium, and chloride ions, but does not specifically target uric acid. It is primarily used to manage edema and hypertension, not uric acid disorders.

D. Indomethacin is a nonsteroidal anti-inflammatory drug (NSAID) used for pain and inflammation management, primarily targeting cyclooxygenase enzymes involved in prostaglandin synthesis. It does not significantly impact uric acid levels or excretion.

**Clinical Pearl:** Hyperuricemia and gout often require specific uricosuric agents like allopurinol, which directly target uric acid synthesis and excretion to effectively manage the condition. NSAIDs like indomethacin primarily address pain and inflammation but do not address elevated uric acid levels. To prevent renal stone formation, maintaining a balanced diet with limited purine intake and adequate hydration is crucial.