Examples: Allopurinol and Febuxostat
Mechanism: Inhibit xanthine oxidase, which, in turn, decreases uric acid production in gout
Indication: Prophylaxis of gout attack in susceptible individuals, as well as in chronic kidney disease and chemotherapy
Dosing:
-once daily *remember to dose adjust for renal impairment
-some patients may require very small doses (every other day)
-with food
-drink lots of water
Adverse Effects:
-may precipitate out an acute gout attack during initiation
-hypersensitivity reaction and rash: more common in HLA B5801 allele positive patients
-nausea and diarrhea
-increased liver function tests
-febuxostat: Health Canada warning of cardiac events (as a result, allopurinol may be preferred)
Drug Interactions:
-azathioprine, theophylline and mercaptopurine: use of xanthine oxidase inhibitors can significantly increase the serum levels due to reduced metabolism
-allopurinol may inhibit warfarin metabolism, resulting in higher INR
-ACE inhibitors: may increase risk of hypersensitivity to allopurinol