Fixed-Dose Rasburicase in Overweight and Obese Patients Versus Normal-Weight Patients

Background: Fixed-dose rasburicase (FDR) is common practice in treating hyperuricemia associated with tumor lysis syndrome in adults; however, there is a lack of data regarding the effectiveness of this dosing strategy specifically in the overweight and obese patient populations. Objective: To determine if patient weight per body mass index (BMI) category is associated with failure of initial FDR as defined by the need for additional dose(s) based on a uric acid level (UAL) >= 7.5 mg/dL within 10 days of previous rasburicase administration. Method: Adults who received FDR per institutional guidelines from October 2008 to August 2013 were reviewed. Patients had either a baseline UAL >= 7.5 mg/dL or were considered high risk (leukemia or lymphoma diagnosis with white blood cell count >50 000/mm(3) or lactate dehydrogenase level greater than 2 times the upper limit of normal). Patients were stratified by BMI as underweight (<18.5), normal (18.5-24.9), overweight (25-29.9), or obese (30+). Result: Overall, 12 out of 151 patients who received FDR required a repeat dose of rasburicase. The percentage of patients requiring a repeat rasburicase dose was not different between obese/overweight versus normal/underweight patients (8.7% vs 6.4%, P = 0.75). Similarly, there was no difference between obese alone versus normal/underweight patients (12.3% vs 6.4%; P = 0.51). Conclusion: In this retrospective analysis, patient BMI did not correlate with failure of FDR in adults, suggesting that this dosing strategy is efficacious in the adult population.