Febuxostat is preferred over allopurinol in patients with renal impairment for chronic gout prophylaxis because:
- A Febuxostat does not require dose adjustment in mild to moderate renal impairment, unlike allopurinol ✓
- B Febuxostat is a uricosuric that promotes renal uric acid excretion
- C Febuxostat inhibits xanthine oxidase reversibly while allopurinol inhibits irreversibly
- D Febuxostat is excreted entirely by the kidney, making it safer when GFR is low
Correct answer: A. Febuxostat does not require dose adjustment in mild to moderate renal impairment, unlike allopurinol
Explanation
Febuxostat is extensively metabolised by the liver (primarily by glucuronidation and oxidation) with only minor renal elimination, so no dose adjustment is needed in mild-moderate CKD (eGFR >30 mL/min). Allopurinol's active metabolite oxypurinol accumulates significantly in renal failure, increasing the risk of allopurinol hypersensitivity syndrome (AHS). Both drugs inhibit xanthine oxidase, but by different mechanisms — febuxostat is a non-purine selective xanthine oxidase inhibitor while allopurinol is a purine analogue.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
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