Which medications in the drug class Xanthine Oxidase Inhibitors are used in the treatment of Gout and Pseudogout?

Updated: Jan 26, 2021
  • Author: Bruce M Rothschild, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Xanthine Oxidase Inhibitors

Inhibition of xanthine oxidase, the enzyme that synthesizes uric acid from hypoxanthine, reduces the synthesis of uric acid without disrupting the biosynthesis of vital purines. This results in the reduction of the tissue stores of uric acid. The goal of therapy is to lower the serum uric acid level to approximately 5-6 mg/dL. These agents should not be started during an attack of acute gouty arthritis without adequate control of the gouty inflammation.

Allopurinol (Zyloprim, Aloprim)

Allopurinol reduces production of uric acid, thereby allowing the body to dispose of excess uric acid stores. It is the most effective therapy for lowering serum uric acid. Most patients achieve the target uric acid level of 5 mg/dL at a dosage of 300-400 mg/day. A lower dosage is used if renal insufficiency is present.

Febuxostat (Uloric)

Febuxostat is a potential alternative to allopurinol. [126, 127] Like allopurinol, febuxostat is a xanthine oxidase inhibitor that prevents uric acid production and lowers elevated serum uric acid levels. Unlike allopurinol, it is a thiazolecarboxylic acid derivative, not a purine base analogue. Febuxostat physically blocks the channel to the molybdenum-pterin active site of xanthine oxidase and is metabolized by liver oxidation and glucuronidation. [42]

Common adverse events include upper respiratory tract infections, arthralgias, diarrhea, headache, and liver function abnormalities. Atrioventricular block or atrial fibrillation and cholecystitis also have been reported. [141] As with other uricosuric agents, initiation of febuxostat may precipitate gouty attacks. [42, 141]


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