Allopurinol

Definition

Allopurinol is an oral xanthine oxidase inhibitor that reduces uric acid production. It is used for chronic gout management, tumor lysis syndrome prophylaxis during chemotherapy, and prevention of uric acid kidney stones.

Mechanism of Action

Allopurinol inhibits the xanthine oxidase enzyme, blocking the conversion of hypoxanthine to xanthine and xanthine to uric acid. This decreases serum uric acid levels over days to weeks.

Adverse Effects

• Stevens-Johnson syndrome and toxic epidermal necrolysis (rare but life-threatening)
• Rash, pruritus
• Elevated liver enzymes
• GI upset
• Drug interactions with azathioprine, mercaptopurine, warfarin

Nursing Considerations

Encourage high fluid intake (2 to 3 L/day) to prevent kidney stones. Administer with food to reduce GI upset. Teach patients to report any rash immediately as an early SJS warning sign. Monitor liver function and CBC. Do NOT start allopurinol during an acute gout attack. Use colchicine or NSAIDs first, then add allopurinol.

NCLEX Relevance

Classic NCLEX emphasis on fluid intake teaching, SJS recognition, and avoiding alcohol and purine-rich foods.