A recombinant modified uricase or urate oxidase that oxidizes uric acid to allantoin.
Can reduce serum uric acid levels within 4 hours.
Given intravenously and results in faster and greater reductions in uric acid than the use of allopurinol.
Reserved for patients with very elevated uric acid levels and renal insufficiency.
Provides superior control of plasma uric acid in randomized trials of pediatric patients with cancer.
Approved for the initial management of plasma uric acid in pediatric patients with leukemia, lymphoma, and solid tumors when anticancer treatment may result in tumor lysis and hyperuricemia.
Rasburicase prophylaxis is considered for a patient with highly proliferative tumors such as AML with a white count of greater than 50,000 per microliter, ALL with white cell count of greater than 100,000 per microliter, Burkett lymphoma, and high grade B or T-cell lymphoma plus a baseline uric acid that level that exceeds 8 mg/dL and a creatinine higher than 1.5 times the baseline level or the upper limit of the normal range.
In a randomized study of adults with hematological malignancies at risk for hyperuricemia rasburicase 0.2 mg/kilogram/day intravenously days one through five, rasburicase plus allopurinol 0.2 mg/kilogram/day intravenously, days one to three followed by oral allopurinol 300 mg/day, days 3-5, or allopurinol 300 mg/day, days one through five: plasma uric acid response was 87% with rasburicase, 78% with rasburicase plus allopurinol and 66% with allopurinol, and the time to uric acid control is four hours for rasburicase, four hours for rasburicase plus allopurinol and 27 hours for allopurinol (Cortes J et al).
A single dose of 1.5 to 7.5 mg abrogates hyperuricemia within 24 to 36 hours in most persons.
It is known to cause Methemoglobinemia particularly in the context of G6PD deficiency.
Rasburicase produces hydrogen peroxide as a byproduct of its activity.
It is recommended to measure G6PD levels before the administration of rasburicase.
Contraindicated in patients with glucose-6-phosphate-dehydrogenase deficiency, secondary for the inability of such patients to break down hydrogen peroxide, and produce urate oxidase reaction.
A single dose of 3 mg of Rasburicase for high risk patients as often sufficient as prophylaxis against tumor lysis, with the additional doses as clinically indicated.