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MUSCULO-SKELETAL SYSTEM › ANTIGOUT PREPARATIONS › ANTIGOUT PREPARATIONS › Preparations inhibiting uric acid production
allopurinol
M04AA01
Forms & Strengths
- Oral tablet: 100 mg
- Oral tablet: 300 mg
- Intravenous injection: 500 mg/vial
Adult Dosing
- Gout (initial): 100 mg orally daily, increased by 100 mg weekly as needed
- Gout (maintenance): 200 to 300 mg daily for mild conditions; up to 800 mg daily for severe conditions
- Tumor lysis syndrome (oral): 300 to 800 mg daily for 2 to 3 days prior to chemotherapy
- Renal impairment adjustment: CrCl 10-20 mL/min: 200 mg daily; CrCl <10 mL/min: 100 mg daily
Pediatric Dosing
- Secondary hyperuricemia associated with chemotherapy (1-10 years): 10 mg/kg/day divided every 8 hours (max 800 mg/day)
- Pediatric gout or hyperuricemia (off-label): 10 mg/kg/day divided q8-12h or once daily (max 300 mg/day)
Indications
- Management of signs and symptoms of primary and secondary gout
- Management of patients with leukemia, lymphoma, and malignancy receiving cancer therapy causing elevation of serum/urinary uric acid levels
- Management of recurrent calcium oxalate renal calculi in patients with hyperuricosuria
Mechanism of Action
- Xanthine oxidase inhibitor
- Reduces the production of uric acid by competitively inhibiting the action of xanthine oxidase, the enzyme that converts hypoxanthine to xanthine and xanthine to uric acid
Contraindications
- Hypersensitivity to allopurinol or any component of the formulation
- Primary idiopathic hemochromatosis (relative/precaution)
Adverse Reactions
- Skin rash, maculopapular rash, pruritus
- Severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome and toxic epidermal necrolysis
- Gastrointestinal: nausea, vomiting, diarrhea, abdominal pain
- Hepatic: transient elevations of serum transaminases, alkaline phosphatase, and hepatotoxicity
- Hematologic: leukopenia, thrombocytopenia, eosinophilia, aplastic anemia (rare)
Drug Interactions
- Azathioprine and 6-mercaptopurine: Allopurinol inhibits xanthine oxidase, significantly increasing toxicity (myelosuppression); reduce dose of these agents by 75%
- Ampicillin and amoxicillin: Increased incidence of skin rash
- Warfarin: Enhanced anticoagulant effect due to inhibition of metabolism
- Thiazide diuretics: Increased risk of allopurinol hypersensitivity reactions and decreased efficacy of allopurinol due to elevated serum uric acid
- Theophylline: Decreased clearance and potential toxicity of theophylline
Curated Content: Needs Vetting Before Put to Clinical Use