Use of single-dose rasburicase in an obese female

OBJECTIVE: To report the use of single-dose rasburicase in an obese patient. CASE SUMMARY: A 53-year-old obese African American woman weighing 136 kg (ideal body weight IBW] 55 kg) with new-onset chronic myelomonocytic leukemia in leukocytic blast crisis was treated with hydroxyurea 5 g daily. In addition, she received allopurinol 300 mg daily for prevention of tumor lysis syndrome (TLS). The following day, allopurinol was discontinued and rasburicase was administered at a dose of 0.2 mg/kg of IBW for a serum uric acid level of 11.9 mg/dL. The patient's serum uric acid level decreased to 1.9 mg/dL 48 hours after a single dose. DISCUSSION: Rasburicase is indicated for the initial management of elevated plasma uric acid levels in patients with hematologic and solid tumor malignancies who are at risk for TLS. This case is unique because the patient received one dose of rasburicase followed by allopurinol rather than 5 daily doses of rasburicase. Additionally, the dose was based on IBW rather than actual body weight. Efficacy of this approach is apparent from the uric acid levels and the lack of hemodialysis requirements. CONCLUSIONS: A single dose of rasburicase (based on IBW) followed by allopurinol can effectively prevent TLS based on serum uric acid concentration. This approach resulted in a substantial cost savings.