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Allopurinol

Oral
Intravenous
Class
Urate-lowering agents
Subclass
Xanthine oxidase inhibitors
Substance name
Allopurinol
Brand names
Zyloprim®
Common formulations
Tablet
Dosage and administration
Adults patients
Treatment
Gout • Mild
•
Start at: 100 mg PO daily
•
Maintenance: 200-300 mg PO daily
•
Maximum: 800 mg per day
Titrate starting dose in 100 mg increments weekly until the serum uric acid concentration is ≤ 6 mg/dL. Administer dosage in excess of 300 mg in divided doses.
Gout • Moderate-to-severe
•
Start at: 100 mg PO daily
•
Maintenance: 400-600 mg PO daily
•
Maximum: 800 mg per day
Titrate starting dose in 100 mg increments weekly until the serum uric acid concentration is ≤ 6 mg/dL. Administer dosage in excess of 300 mg in divided doses.
Nephrolithiasis in patients with hyperuricosuria • Recurrent, due to calcium oxalate stones
•
Maintenance: 200-300 mg PO daily, in 1-2 divided doses
•
Maximum: 800 mg per day
Adjust the dose upwards or downwards depending upon control of the hyperuricosuria as assessed by 24-hour urinary urate determinations.
Prevention
Prevention of chemotherapy-induced hyperuricemia in patients with malignancies
•
300-800 mg PO daily, started 24-48 hours before chemotherapy and continued until the risk of tumor lysis has abated
Indications for use
Labeled indications
Adults
•
Treatment of gout (mild)
•
Treatment of gout (moderate-to-severe)
•
Treatment of nephrolithiasis in patients with hyperuricosuria (recurrent, due to calcium oxalate stones)
•
Prevention of chemotherapy-induced hyperuricemia in patients with malignancies
Safety risks
Contraindications
Hypersensitivity to allopurinol or its components
HLA-B*58:01 allele carriers
•
Consider screening for HLA-B*58:01 before initiating allopurinol in patients from populations with high prevalence of HLA-B*58:01 allele, such as African, Han Chinese, Korean, Thai, and Native Hawaiian/Pacific Islander ancestry.
Warnings and precautions
AKI
•
Use caution in patients with pre-existing renal disease, including CKD or a history of kidney stones. Monitor kidney function frequently during the initiation of treatment. Maintain adequate fluid intake to yield a urinary output of at least 2 L/day of neutral or, preferably, slightly alkaline urine to avoid the formation of xanthine calculi.
Drug hypersensitivity reaction
•
Use caution in patients with decreased renal function receiving thiazide diuretics.
Gout flares
•
Use caution in patients with gout. Administer prophylactic treatment with colchicine or an anti-inflammatory agent.
Increased serum transaminases, increased serum ALP
•
Use caution in all patients. Assess liver enzymes if anorexia, weight loss, or pruritus develop. Monitor liver enzymes periodically in patients with pre-existing liver disease.
Myelosuppression
•
Use caution in all patients, particularly with concomitant use of cytotoxic drugs. Monitor blood counts more frequently when used with cytotoxic drugs.
Skin rash
•
Use caution in patients taking bendamustine, ampicillin, or amoxicillin.
Somnolence
•
Use extreme caution in patients performing activities requiring mental alertness, such as driving or operating machinery.
Specific populations
Renal impairment
CrCl > 20 mL/min
•
Monitor renal function. Monitor for skin rash.
CrCl 10-20 mL/min
•
Start at dose of 100 mg/day. Maximal dose of 200 mg/day. Do not exceed frequency of once daily. Monitor renal function. Monitor for skin rash.
CrCl < 10 mL/min
•
Maximal dose of 100 mg/day. Do not exceed frequency of once daily. Monitor renal function. Monitor for skin rash. Consider increasing frequency to q48h in patients with CrCl < 3 mL/min.
Renal replacement therapy
Continuous renal replacement
•
No guidance available.
Intermittent hemodialysis
•
Maximal dose of 50 mg BID or 100 mg once daily. Monitor renal function. Monitor for skin rash.
Peritoneal dialysis
•
No guidance available.
Hepatic impairment
Any severity
•
No guidance available.
Pregnancy and breastfeeding
Pregnancy
All trimesters • Australia Category: B2
•
Use only if benefits outweigh potential risks. Evidence of fetal harm in animals. Experience with allopurinol during human pregnancy is limited, partly because it is seldom required by women of reproductive age.
Breastfeeding
Use only if benefits outweigh potential risks.
•
Monitor infants for allergic reactions, such as rash, and obtain periodic CBC and differential blood counts.
Low-moderate levels in breastfed infants (25-45%).
No overt adverse effects reported in breastfed infants.
Adverse reactions
Common 1-10%
•
↑ serum ALP, maculopapular rash, diarrhea, nausea
Uncommon < 1%
•
Acute liver failure, acute pericarditis, atopic dermatitis, ↓ blood neutrophil count, ↓ platelet count, ecchymosis, exfoliative dermatitis, gastritis, gout flares, hepatomegaly, ↑ WBC count, ↑ blood eosinophil count, ↑ serum TBIL, jaundice, necrotizing vasculitis, peripheral neuropathy, renal failure, abdominal pain, dyspepsia, fever, headache, hematuria, joint pain, nosebleed, paresthesia, somnolence, vomiting, splenomegaly, Stevens-Johnson syndrome, toxic epidermal necrolysis, vasculitis
Unknown frequency
•
DRESS syndrome, ↑ serum transaminases
Interactions
Drug(s)
Check Interactions
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