Allopurinol Dosing in Renal Impairment

Initial Dosing and Titration

• The American College of Rheumatology recommends starting allopurinol at 50-100 mg daily, regardless of renal function, and titrating upward every 2-5 weeks with careful monitoring, to achieve serum uric acid <6 mg/dL 1, 2
• Begin with 50-100 mg daily (50 mg if eGFR <30 mL/min) and increase by 50-100 mg increments every 2-5 weeks, monitoring serum uric acid every 2-4 weeks during titration 1, 2

Monitoring and Dose Adjustment

• Monitor serum uric acid levels every 2-4 weeks during dose adjustment, and liver function tests periodically, given hepatitis risk with allopurinol hypersensitivity syndrome (AHS) 1, 2
• Reduce azathioprine or 6-mercaptopurine doses by 65-75% if used concomitantly with allopurinol 2

Alternative Therapies

• Febuxostat requires no dose adjustment in mild to moderate renal impairment and can be used at standard doses (40-80 mg daily) regardless of CKD stage 1, 2
• Benzbromarone (100-200 mg daily) is more effective than allopurinol in patients with renal impairment, but carries hepatotoxicity risk and has restricted availability 3, 4

Flare Prophylaxis

• Prophylactic colchicine should be initiated when starting allopurinol, with standard dose: 0.6 mg daily, and reduced to 0.3 mg daily or 0.6 mg every other day in severe renal impairment (eGFR <30) 2, 3

Critical Considerations

• The American College of Rheumatology and other guidelines recommend against starting with standard 300 mg doses in renal impairment, as this dramatically increases toxicity risk 1
• Do not discontinue allopurinol once symptoms are controlled, as this leads to recurrent gout flares 2, 5