Single 6-mg dose of rasburicase: The experience in a large academic medical center.

BACKGROUND: Tumor lysis syndrome is an oncologic emergency due to the release of tumor cell contents, leading to metabolic derangements. Rasburicase, a recombinant urate oxidase, catabolizes uric acid. At our institution, we administer a single 6-mg dose of rasburicase to patients who are at risk for tumor lysis syndrome. We aimed to assess the efficacy of single 6-mg dose of rasburicase and explore risk factors associated with rasburicase failure. METHODS: We report results in 92 adult patients who had a baseline uric acid greater than 7.5 mg/dL and received a single 6-mg dose of rasburicase for the management of tumor lysis syndrome. Responders were defined as those whose uric acid was less than or equal to 7.5 mg/dL within 24-36 h of rasburicase administration. The primary end point was response based on uric acid level. Secondary end points included response to rasburicase in association with lactate dehydrogenase, serum creatinine, calcium, phosphorus, blood pH, and oncologic diagnosis. RESULTS: Median age was 65 years and 70% were men. Most patients had leukemia (32%) or lymphoma (40%). Eighty-seven of 92 patients (95%), who received single 6-mg dose of rasburicase, achieved a uric acid less than 7.5 mg/dL within 24-36h of dosing. Body mass index was similar between responders and non-responders: 28.6 kg/m2 vs. 26.6 kg/m2, respectively, p = 0.6. Baseline lactate dehydrogenase levels were similar between the groups: 756 U/L vs. 892 U/L, respectively, p = 0.33. Blood pH values documented within 24 h of first dose of rasburicase were also similar between the two groups (n = 30; 7.33 vs. 7.34 respectively, p = 0.6). However, median baseline uric acid was lower in responders than non-responders: 12.3 mg/dL vs. 17.3 mg/dL, respectively, p = 0.012. Baseline serum creatinine and creatinine clearance were similar between responders and non-responders (2.2 mg/dL vs. 3.95 mg/dL; p = 0.12 and 29 mL/min vs. 16 mL/min; p = 0.11, respectively). CONCLUSIONS: Higher baseline uric acid levels were observed in patients who did not respond to the first rasburicase dose. In our study, uric acid levels normalized in 95% of patients after a single 6-mg dose of rasburicase indicating that a single 6-mg dose of rasburicase may be sufficient to manage tumor lysis syndrome, for most patients.

Nephrotoxicity of Natural Products.

BACKGROUND: The manufacture and sale of natural products constitute a multi-billion dollar industry. Nearly a third of the American population admit to using some form of complementary or alternative medicine, with many using them in addition to prescription medications. Most patients fail to inform their healthcare providers of their natural product use and physicians rarely inquire. Annually, thousands of natural product-induced adverse events are reported to Poison Control Centers nationwide. Natural product manufacturers are not responsible for proving safety and efficacy, as the FDA does not regulate them. However, concerns exist surrounding the safety of natural products. SUMMARY: This review provides details on natural products that have been associated with renal dysfunction. We have focused on products that have been associated with direct renal injury, immune-mediated nephrotoxicity, nephrolithiasis, rhabdomyolysis with acute renal injury, hepatorenal syndrome, and common adulterants or contaminants that are associated with renal dysfunction. KEY MESSAGES: The potential for natural products to cause renal dysfunction is justifiable. It is imperative that natural product use be monitored closely in all patients. Healthcare practitioners must play an active role in identifying patients using natural products and provide appropriate patient education.