Pharmacology · Chemotherapy supportive agents
Rasburicase !
A recombinant urate oxidase enzyme that turns uric acid into soluble allantoin in tumour lysis. It must not be given in G6PD deficiency.
Updated 2026-11-01
The structure shows urate oxidase from the mould Aspergillus flavus, the kind of enzyme rasburicase is, holding the inhibitor 8-azaxanthine in its urate-binding site.
Mechanism of action
Humans lack urate oxidase, so uric acid is the end product of purine breakdown. Rasburicase supplies the enzyme: it oxidises uric acid to allantoin, which is far more soluble and easily excreted. The reaction produces hydrogen peroxide; red cells with too little G6PD cannot neutralise it, leading to haemolysis and methaemoglobinaemia.
- Tumour lysis floods the blood with uric acid
- Rasburicase oxidises uric acid to allantoin
- Soluble allantoin is excreted: kidneys protected
- The H2O2 by-product is dangerous if G6PD is low
Pharmacokinetics
- Absorption
- Intravenous infusion in hospital, as a single short course.
Indications
- High uric acid in people with certain cancers receiving chemotherapy, as tumour cells break down (tumour lysis). Tumour lysis syndrome →
Adverse effects
Common
- Nausea, vomiting, diarrhoea or constipation, abdominal pain
- Fever, headache, mouth sores
- Swelling of the legs; pain or redness at the injection site
Contraindications
- G6PD deficiency (people of African or Mediterranean ancestry are screened first)
- Previous severe allergic reaction to rasburicase
Key interactions
- Uric acid laboratory tests
- Rasburicase can affect the results; the laboratory is told the patient is receiving it.
What is monitored
- G6PD status before the first dose
- Uric acid, potassium, phosphate, calcium and creatinine
- Signs of haemolysis or methaemoglobinaemia (colour, oxygen saturation, urine)
Administration and safety
- Given by intravenous infusion in hospital; the infusion is stopped at once if an allergic reaction occurs.
- Usually a single course that is not repeated.
- Before uric acid samples are drawn, the laboratory is told that the patient is receiving rasburicase.
Nursing care
- Confirm the G6PD result before the first dose.
- Watch for chest tightness, wheeze, hives or swelling of the lips during the infusion.
- Watch skin colour and oxygen saturation; report dark urine, jaundice or confusion.
- Strict intake and output during tumour lysis prevention.
Test yourself
Think of the answer, then tap the question to see it.
What does rasburicase convert uric acid into?
Allantoin, which is much more soluble and easily excreted.
Why is rasburicase dangerous in G6PD deficiency?
The reaction makes hydrogen peroxide; G6PD-deficient red cells cannot neutralise it, causing haemolysis and methaemoglobinaemia.
Why do humans need a drug to break down uric acid that many mammals break down themselves?
Humans lack a functional urate oxidase (uricase), so uric acid is our end product of purine breakdown.
Related drugs
Related conditions
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Rasburicase Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2016); Farmacología básica y clínica (Katzung), cap. 5 (McGraw Hill, 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 7 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.