MRCP2-4715

A 68-year-old man has been experiencing painful swelling in his right knee and difficulty walking for the past three days. He has also had two instances of severe pain and swelling in his right big toe within the last year. A knee aspiration revealed the presence of leukocytes but no organisms on Gram stain, as well as negatively birefringent crystals on polarised light microscopy. Recent blood tests showed normal renal function, but a raised serum urate level of 452 µmol/L (210-415 µmol/L). What is the next step in managing his condition in the long term, once the current episode of acute synovitis has subsided?