Perthes Disease — Practice

A 45-year-old man develops sudden severe pain in the great toe of the right foot at night, with the metatarsophalangeal joint appearing red, hot and exquisitely tender. Aspiration of synovial fluid examined under polarised light microscopy shows needle-shaped, strongly negatively birefringent crystals. Which is the drug of choice for an acute attack in a patient with normal renal function and no peptic ulcer disease?