DRUG CLASS AND MECHANISM: Allopurinol is used for treating gout caused by excessive levels of uric acid in the blood (hyperuricemia). It is a xanthine oxidase inhibitor and is similar to febuxostat (Uloric). read more
Mechanism of action Allopurinol is a purine analog; it is a structural isomer of hypoxanthine (a naturally occurring purine in the body) and is an inhibitor of the enzyme xanthine oxidase. Xanthine oxidase is responsible for the successive oxidation of hypoxanthine and xanthine, resulting in the production of uric acid, the product of human purine metabolism. read more
The action of Allopurinol differs from that of uricosuric agents, which lower the serum uric acid level by increasing urinary excretion of uric acid. Allopurinol reduces both the serum and urinary uric acid levels by inhibiting the formation of uric acid. read more
While not specifically related to the mechanism of action in gout, febuxostat, unlike allopurinol, is a substrate of uridine diphosphate glucuronosyltransferase (UGT) 1A1, 1A3, 1A9, 2B7 and cytochrome P-450 (CYP) 1A2, 2C8, and 2C9.8 In addition, febuxostat is also known to be a weak inhibitor of CYP2D6.8 As such, febuxostat may be subject to more drug interactions than compared to allopurinol. read more