Allopurinol is a xanthine oxidase inhibitor used to decrease high blood uric acid levels. Allopurinol is specifically used to prevent gout, prevent specific types of kidney stones, and for the high uric acid levels that can occur with chemotherapy. Allopurinol acts on purine catabolism, without disrupting the biosynthesis of purines. It reduces the production of uric acid by inhibiting the biochemical reactions immediately preceding its formation. Allopurinol is a structural analog of the natural purine base, hypoxanthine. It is an inhibitor of xanthine oxidase, the enzyme responsible for the conversion of hypoxanthine to xanthine and of xanthine to uric acid, the end product of purine metabolism in man. Allopurinol is metabolized to the corresponding xanthine analog, oxypurinol (Allopurinol), which also is an inhibitor of xanthine oxidase. Allopurinol is taken by mouth or injected into a vein. Common side effects, when used by mouth, include itchiness and rash. Common side effects when used by injection include vomiting and kidney problems.

Arhalofenate is a uricosuric drug which lowers serum urate by blocking its reabsorption by the proximal tubules of the kidney. Arhalofenate activity is mediated by inhibition of URAT1, OAT4 and OAT10. Additionally, arhalofenate has been suggested to exert potent anti-inflammatory activity. Arhalofenate has completed Phase 2 and is ready to advance to Phase 3 as a novel potential treatment for gout. The drug was also tested in patients with type 2 diabetes mellitus (phase III study), where it demonstrated its ability to lower glucose level, acting as a selective, partial PPAR-gamma agonist. However, the development of arhalofenate as an anti-diabetic drug was terminated.