Dosing & Uses
Dosage Forms & Strengths
40 mg/day PO initially; maintenance: 40-80 mg/day; increased if serum uric acid is >6 mg/mL after 2 weeks
- Mild to moderate (CrCl 30-89 mL/min): Dosage adjustment not necessary
- Severe (CrCl <30 mL/min): Data not available; use with caution
- Mild to moderate (Child-Pugh class A or B): Dosage adjustment not necessary
- Severe (Child-Pugh class C): Data not available; use with caution
Safety and efficacy not established
Serious - Use Alternative
Significant - Monitor Closely
Elevated liver function test (LFT) results
Liver function abnormalities
Immunologic: Anaphylaxis, anaphylactic reaction
Hepatobiliary: Hepatic failure (some fatal), jaundice, serious cases of abnormal LFT results, liver disorders
Psychiatric: Psychotic behavior, including aggressive thoughts
Renal and urinary: Tubulointerstitial nephritis
Dermatologic: Generalized rash, Stevens-Johnson syndrome, hypersensitivity skin reactions
Coadministration with azathioprine, mercaptopurine, or theophylline
After initiation, gout flare frequently occurs; provide prophylaxis with nonsteroidal anti-inflammatory drug (NSAID) or colchicine upon initiation and for ≤6 months
Not indicated for asymptomatic hyperuricemia
Not tested for secondary hyperuricemia
Higher incidence of cardiovascular thromboembolic events than with allopurinol in clinical trials; monitor for symptoms of myocardial infarction and stroke
May increase liver enzyme activity; obtain LFTs at baseline, and do not initiate if alanine aminotransferase is 3 times upper limit of normal with total bilirubin >2 times upper limit of normal
Postmarketing reports of fatal and nonfatal hepatic failure
Pregnancy & Lactation
Pregnancy category: C
Lactation: Unknown whether drug is excreted into breast milk; use with caution
A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA:Information not available.
Mechanism of Action
Xanthine oxidase inhibitor; inhibits conversion of hypoxanthine to xanthine to uric acid; at therapeutic dosages, decreases production of uric acid without disrupting synthesis of vital purines and pyrimidines
Peak plasma time: 1-1.5 hr
Protein bound: 99.2%
Vd: 50 L
Metabolized by UGT1A1, UGT1A3, UGT1A9, and UGT2B7; oxidized by CYP1A2, CYP2C8, and CYP2C9; also metabolized by non-CYP450 enzymes
Half-life: 5-8 hr
Excretion: Feces (45%; 12% unchanged), urine (49%; 3% unchanged)
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|1||This drug is available at the lowest co-pay. Most commonly, these are generic drugs.|
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