Section: USMLE

47) A 44-year-old businessman presents to a physician because of a markedly inflamed and painful right great toe. He states that he just returned from a convention, and noticed increasing pain in his right foot during his plane trip home. Physical examination is remarkable for swelling and erythema of the right great toe as well as small nodules on the patient’s external ear. Aspiration of the metatarsal-phalangeal joint of the affected toe demonstrates needle-shaped negatively birefringent crystals. Which of the following agents would provide the most immediate relief for this patient?

1. Allopurinol
2. Aspirin
3. Colchicine
4. Probenecid
5. Sulfinpyrazone

The patient has gout, which is due to precipitation of monosodium urate crystals in joint spaces (notably the great toe) and soft tissues (causing tophi, which are often found on the external ears). Colchicine reduces the inflammation caused by the urate crystals by inhibiting leukocyte migration and phagocytosis secondary to an effect on microtubule assembly.

Allopurinol and its metabolite, oxipurinol, inhibit xanthine oxidase, the enzyme that forms uric acid from hypoxanthine. Therapy with this agent should be begun 1-2 weeks after the acute attack has subsided.

Aspirin competes with uric acid for tubular secretion, thereby decreasing urinary urate excretion and raising serum uric acid levels. At high doses (more than 2 gm daily) aspirin is a uricosuric.

Probenecid and sulfinpyrazone are uricosuric agents, increasing the urinary excretion of uric acid, hence decreasing serum levels of the substance. Therapy with these agents should be begun 1-2 weeks after the acute attack has subsided.