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MBBS QUESTION #10364
Question 1
Allopurinol, commonly used in the long-term management of gout, lowers uric acid production by inhibiting which enzyme?
  • Hypoxanthine-guanine phosphoribosyltransferase (HGPRT)
  • Xanthine oxidase✔️
  • Adenosine deaminase
  • Phosphoribosyl pyrophosphate (PRPP) synthetase
Correct Answer Explanation
Xanthine oxidase catalyzes the final steps of purine catabolism (hypoxanthine to xanthine to uric acid); allopurinol (and its active metabolite oxypurinol) inhibits this enzyme, reducing uric acid production and shifting excretion toward the more soluble precursors hypoxanthine and xanthine.