PEBC: What You Need to Know: Uricosuric Agents

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