Alopron is a xanthine oxidase inhibitor which is administered orally. It acts on purine catabolism without disrupting the biosynthesis of purine. It reduces the production of uric acid by inhibiting the biochemical reactions immediately preceding its formation. Alopron is a structural analogue of the natural purine base, hypoxanthine. It is an inhibitor of xanthine oxidase, the enzyme responsible for the conversion of hypoxanthine to xanthine and xanthine to uric acid, the end product of purine metabolism. Alopron decreases the production of uric acid by stopping the biochemical reactions that precede its formation . This process decreases urate and relieves the symptoms of gout, which may include painful tophi, joint pain, inflammation, redness, decreased range of motion, and swelling .