Prevention of Tumor Lysis Syndrome

Introduction to Alopurinol Dosage

The recommended dose of alopurinol for preventing tumor lysis syndrome is 100 mg/m² every 8 hours orally (10 mg/kg/day divided every 8 hours) with a maximum dose of 800 mg/day, or 200-400 mg/m²/day in 1-3 divided doses intravenously (maximum 600 mg/day) 1
The same dosing is used for pediatric patients, with treatment starting 1-2 days before chemotherapy and continuing for 3-7 days after, depending on the ongoing risk of tumor lysis syndrome development 1

In patients with renal insufficiency, the dose should be reduced by 50% or more, with specific adjustments based on creatinine clearance (e.g., 200 mg/day for a creatinine clearance of 10-20 mL/min, and not exceeding 100 mg/day for a creatinine clearance of less than 10 mL/min) 1
When used concomitantly with 6-mercaptopurine/azathioprine, the doses of these medications should be reduced by 65-75% 1

Treatment should be initiated 24-48 hours before chemotherapy and continued for 3-7 days after chemotherapy, based on the risk of tumor lysis syndrome 1, 2
Vigorous hydration (2-3 L/m²/day) should be maintained, with monitoring of urine output aiming for 80-100 mL/m²/hour in pediatric patients and 100 mL/hour in adults 1, 2

Patients should be monitored for serum uric acid, electrolytes (potassium, calcium, phosphorus), renal function, and other parameters every 6-12 hours during the first 24-72 hours, then daily 2

For patients with pre-existing hyperuricemia (>450 μmol/L or 7.5 mg/dL), rasburicase is preferred over alopurinol 1
Rasburicase (0.20 mg/kg/day IV) may be considered as first-line treatment for high-risk patients, while alopurinol is appropriate for intermediate to low-risk patients 2

Alopurinol only prevents new uric acid formation and does not reduce existing uric acid levels 1
It can increase serum xanthine and hypoxanthine levels, risking xanthine crystal deposits in renal tubules 1
Potential drug interactions include those with dicumarol, uricosuric agents, thiazide diuretics, ampicillin/amoxicillin, cyclophosphamide, chlorpropamide, and cyclosporine 1
Alopurinol should not be administered simultaneously with rasburicase, as it reduces the efficacy of rasburicase 2