Drug Mnemonic

Allopurinol

AntiGout • Xanthine oxidase Inhibitor • gout prevention
May 4, 2026
RxMnemonic Antigout
Allopurinol
AntiGout • Xanthine oxidase Inhibitor • gout prevention
ALLO = all + PURIN = purines +OL = all
Separate allopurinol into ALLO (sounds like All), PURIN (sounds like purine), and OL (sounds like all again). Allopurinol is ALL - PURINE - ALL. It loves purines so much that it blocks ALL other love (XO) from both sides, thus ALL - PURINE - ALL. And XO? That stands for the enzyme allopurinol blocks: Xanthine Oxidase (XO). 
Allopurinol
Antigout ALLO = all | PURIN - purine | OL = all
HOW STEP TESTS IT
1
Allopurinol inhibits xanthine oxidase, blocking hypoxanthine -> xanthine -> uric acid, lowering serum urate and preventing gout flares.
2
Side effects: Can paradoxically trigger a gout flare on initiation. Avoid in patients taking azathioprine or 6-mercaptopurine (xanthine oxidase metabolizes both and blocking xanthine oxidase causes these to accumulate at toxic levels. 
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Practice Question

A 52 year-old man with chronic gout is started on allopurinol. Three weeks later he returns with a swollen, hot first MTP joint. What is the most appropriate step?

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