Febuxostat differs from allopurinol in the treatment of gout by:
- A Being a competitive substrate analog that irreversibly inhibits xanthine oxidase
- B Being a non-purine selective inhibitor of xanthine oxidase — non-competitive, not requiring conversion to an active metabolite ✓
- C Increasing renal uric acid excretion by blocking URAT1 transporter
- D Inhibiting de novo purine synthesis upstream of xanthine oxidase
Correct answer: B. Being a non-purine selective inhibitor of xanthine oxidase — non-competitive, not requiring conversion to an active metabolite
Explanation
Allopurinol is a purine analog that is converted to oxypurinol, which then competitively inhibits xanthine oxidase. Febuxostat is a non-purine, selective, non-competitive inhibitor of xanthine oxidase that does not require activation to a metabolite. Because it is non-purine, it avoids many drug interactions related to purine metabolism and is metabolized hepatically (not renally), making it usable at reduced doses in mild-to-moderate renal impairment where allopurinol dose reduction is more complex.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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