Allopurinol
ZYLOPRIM
What it isXanthine oxidase inhibitor; urate lowering for gout and tumor-lysis prophylaxis.
Why this oneIts long safety record, low cost and usability in kidney disease keep it first-line over febuxostat.
What limits itStart low and titrate to urate while covering flares. Screen HLA-B*5801 when indicated; azathioprine exposure can become dangerous.
FDA-approved for
- gout (~1966)
Off-label
- tumor lysis prevention
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Gout | Adults, normal renal function | 100 mg QD | Increase by 100 mg weekly to uric acid ≤6 mg/dL | 800 mg/day |
| Gout | Renal impairment | 50 mg QD | Titrate per eGFR (see renal) | |
| Hyperuricemia with cancer therapy | Adults | 300-800 mg QD | 800 mg/day | |
| Hyperuricemia with cancer therapy | Pediatric | 100 mg/m² q8-12h (10 mg/kg/day) | 800 mg/day | |
| Recurrent calcium oxalate calculi | Adults | 200-300 mg QD |
Titration Gout: increase by 100 mg weekly (renal impairment: 50 mg every 2-4 weeks)
Renal Reduce initial dose per eGFR (gout: 50 mg QD if eGFR 30-60; 50 mg every other day 15-30; 50 mg twice weekly 5-15; 50 mg weekly <5)
Hepatic Undefined
Instructions
- Take after meals; maintain fluid intake for ≥2 L/day urine output
- Doses above 300 mg/day: give in divided doses
- Start gout-flare prophylaxis (colchicine or anti-inflammatory) at initiation and continue during titration
- Discontinue immediately at first appearance of rash or other hypersensitivity signs
- Cancer therapy: begin 24-48 hours before chemotherapy
Cautions
- Serious/fatal skin reactions and hypersensitivity (SJS, TEN, DRESS); higher risk with HLA-B*58:01 — discontinue at first sign of rash
- Gout flares on initiation — use prophylaxis
- Nephrotoxicity (xanthine calculi, urate precipitation) — hydrate; monitor renal function
- Hepatotoxicity — monitor liver enzymes
- Myelosuppression (anemia, leukopenia, thrombocytopenia)
- Drowsiness/dizziness — caution driving/operating machinery
Adverse reactions
- Skin rash (most common), nausea, diarrhea, increased liver function tests, acute gout attacks
Pregnancy May cause fetal harm based on animal findings; limited human data do not show a clear pattern. Crosses the placenta.
Lactation Allopurinol and oxypurinol are present in human milk; do not breastfeed during treatment and for 1 week after the last dose.
NO BOXED WARNINGS
Principal riskSevere cutaneous adverse reactions, HLA-B*5801-linked
Cost, est. cash$4–$80/month
Generic entry1985
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.
Mechanism of action: Allopurinol ballicule
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Memory aids: mascots and interaction avatars
Podagra / gout cue retained in the image
