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Elitek

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Elitek

Warnings
Precautions

WARNINGS

Included as part of the PRECAUTIONS section.

PRECAUTIONS

Anaphylaxis

The safety and efficacy of Elitek (rasburicase) have been established only for a single course of treatment once daily for 5 days.

Elitek (rasburicase) can cause severe allergic reactions including anaphylaxis. In clinical studies, anaphylaxis was reported in < 1% patients receiving Elitek (rasburicase) . This can occur at any time during treatment including the first dose. Signs and symptoms of these reactions include bronchospasm, chest pain and tightness, dyspnea, hypoxia, hypotension, shock, and urticaria. Immediately and permanently discontinue Elitek (rasburicase) administration in any patient developing clinical evidence of a serious hypersensitivity reaction [see Boxed Warning, CONTRAINDICATIONS, ADVERSE REACTIONS].

Hemolysis

Elitek (rasburicase) is contraindicated in patients with G6PD deficiency because hydrogen peroxide is one of the major by-products of the conversion of uric acid to allantoin. In clinical studies, hemolysis occurs in < 1% patients receiving Elitek (rasburicase) ; severe hemolytic reactions occurred within 2-4 days of the start of Elitek (rasburicase) . Immediately and permanently discontinue Elitek (rasburicase) administration in any patient developing hemolysis. Institute appropriate patient monitoring and support measures (e.g., transfusion support). Screen patients at higher risk for G6PD deficiency (e.g., patients of African or Mediterranean ancestry) prior to starting Elitek [see Boxed Warning, CONTRAINDICATIONS].

Methemoglobinemia

In clinical studies, methemoglobinemia occurred in < 1% patients receiving Elitek (rasburicase) . These included cases of serious hypoxemia requiring intervention with medical support measures. It is not known whether patients with deficiency of cytochrome b5 reductase (formerly known as methemoglobin reductase) or of other enzymes with antioxidant activity are at increased risk for methemoglobinemia or hemolytic anemia. Immediately and permanently discontinue Elitek (rasburicase) administration in any patient identified as having developed methemoglobinemia. Institute appropriate monitoring and support measures (e.g., transfusion support, methylene-blue administration) [see Boxed Warning, CONTRAINDICATIONS].

Laboratory Sample Handling Procedure

At room temperature, Elitek (rasburicase) causes enzymatic degradation of the uric acid in blood/plasma/serum samples potentially resulting in spuriously low plasma uric acid assay readings. The following special sample handling procedure must be followed to avoid ex vivo uric acid degradation.

Uric acid must be analyzed in plasma. Blood must be collected into pre-chilled tubes containing heparin anticoagulant. Immediately immerse plasma samples for uric acid measurement in an ice water bath. Plasma samples must be prepared by centrifugation in a pre-cooled centrifuge (4°C). Finally, the plasma must be maintained in an ice water bath and analyzed for uric acid within four hours of collection [see Boxed Warning].

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenicity studies in animals to evaluate tumoriogenic potential of rasburicase have not been performed. Rasburicase was not mutagenic in the Ames, unscheduled DNA synthesis, chromosome analysis, mouse lymphoma, and micronucleus tests.

Rasburicase did not affect reproductive performance or fertility in male or female rats at a dose 50-fold higher (10 mg/kg) than the recommended human dose.

Use In Specific Populations

Pregnancy

Pregnancy Category C

There are no studies of rasburicase in pregnant women. Reproductive toxicity studies in rabbits treated during organogenesis with approximately 10 to 100 times the recommended human dose of rasburicase resulted in teratogenicity, including decreased fetal body weights and heart and great vessel malformations at all dose levels. Multiple heart and great vessel malformations were also observed in offspring of pregnant rats treated with approximately 250 times the recommended human dose of rasburicase. Other adverse effects were observed in rasburicase-treated pregnant rabbits at all dose levels tested and included pre- and post-implantation losses, abortions, and decreased uterine weights [See Nonclinical Toxicology].

It is unknown whether rasburicase can cross the placental barrier in humans and result in fetal harm. Because of the observed teratogenic effects of rasburicase in animal reproductive studies, use rasburicase during pregnancy only if the potential benefit to the mother justifies the potential risk to the fetus.

Nursing Mothers

It is not known whether rasburicase is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from rasburicase, a decision should be made whether to discontinue nursing or to discontinue rasburicase, taking into account the importance of the drug to the mother.

Pediatric Use

The safety and efficacy of Elitek (rasburicase) was studied in 246 pediatric patients ranging in age from 1 month to 17 years. There were insufficient numbers of patients between 0 and 6 months (n=7) to determine whether they respond differently from older children. Mean uric acid AUC0-96 hr was higher in children < 2 years of age (n=24; 150 ± s.e. 16 mg hr/dL) than those age 2 to 17 years (n=222; 108 ± s.e. 4 mg hr/dL). Children < 2 years of age had a lower rate of achieving normal uric acid concentration by 48 hours [83% (95% CI: 62, 95)] than those 2 to 17 years [93% (95% CI: 89, 95)].

Geriatric Use

Of the total number of adults treated with Elitek (rasburicase) (n=434) in clinical studies, 30% were aged 65 and over while 8% were aged 75 and over. No overall differences in pharmacokinetics, safety, and effectiveness were observed between the elderly and younger patients.

Last reviewed on RxList: 11/2/2009
This monograph has been modified to include the generic and brand name in many instances.

Warnings
Precautions
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