Tumour Lysis Syndrome Pregnancy: May cause fetal harm based on animal findings (structural abnormalities, embryo-fetal mortality, altered growth in rabbits at ~5x human exposure). Limited human data are insufficient; consider benefits and risks when prescribing in pregnancy (US label §8.1).

Rasburicase

Brand names: Fasturtec

Rasburicase is a recombinant urate oxidase enzyme used to treat and prevent acute hyperuricaemia, notably in tumour lysis syndrome, where it protects renal function.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 0.2 mg/kg

Route: Intravenous infusion over 30 minutes

Frequency: Once daily for up to 5 days

Recommended dose 0.2 mg/kg as a 30-minute IV infusion daily for up to 5 days for initial management of plasma uric acid in patients receiving anticancer therapy expected to cause tumour lysis. Do not administer as an IV bolus. Dosing beyond 5 days or more than one course is not recommended; safety and efficacy established only for a single course once daily for 5 days. Reconstitute with the supplied diluent; inject the calculated dose into 0.9% sodium chloride to a final total volume of 50 mL and infuse over 30 minutes through a separate line, or flush the line with >=15 mL normal saline before and after. No renal-impairment-specific dose adjustment is provided in the US label (this variant is tagged 'renal' for context only).

Paediatric dose

Dose: 0.2 mg/kg

Route: Intravenous infusion over 30 minutes

Frequency: Once daily for up to 5 days

Same 0.2 mg/kg once-daily regimen as adults. Safety and effectiveness established in paediatric patients ages 1 month to 17 years; insufficient data in those 0-6 months. Children <2 years had higher uric acid AUC and a lower rate of achieving normal uric acid by 48 hours than those 2-17 years (US label §8.4).

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Paediatric weight-based calculator

Patient weight (kg)

Verify in a children's formulary

Contraindications

History of anaphylaxis or severe hypersensitivity to rasburicase
Development of haemolytic reactions or methaemoglobinaemia with rasburicase
Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Side effects

Vomiting, nausea (incidence >=20%)
Fever; headache; abdominal pain (incidence >=20%)
Peripheral oedema; constipation; diarrhoea (incidence >=20%)
Hypophosphataemia; increased alanine aminotransferase; pharyngolaryngeal pain
Anaphylaxis, haemolysis and methaemoglobinaemia (serious, boxed-warning reactions)

Interactions

Laboratory test interference: rasburicase causes ex vivo enzymatic degradation of uric acid in blood/plasma/serum, giving spuriously low uric acid readings — collect blood into pre-chilled heparin tubes, keep in an ice-water bath, centrifuge at 4°C, and analyse within 4 hours
No metabolic-based drug interactions anticipated — rasburicase does not metabolise allopurinol, cytarabine, methylprednisolone, methotrexate, 6-mercaptopurine, thioguanine, etoposide, daunorubicin, cyclophosphamide or vincristine in vitro

Clinical monograph

How it works

It catalyses the oxidation of uric acid to allantoin, a more soluble compound that is more readily excreted, rapidly lowering plasma urate.

Prescribing in practice

Rasburicase is contraindicated in glucose-6-phosphate dehydrogenase deficiency because it can precipitate severe haemolysis and methaemoglobinaemia; screen at-risk patients before use.
Hypersensitivity and anaphylaxis can occur, so administer under appropriate supervision with resuscitation facilities available.
Blood samples for uric acid measurement require special handling on ice, as rasburicase continues to degrade urate in vitro and falsely lowers results.

Monitoring

Monitor uric acid (using correctly handled samples), renal function and signs of haemolysis or hypersensitivity during therapy.

Counselling the patient

Tell your team immediately if you feel breathless, develop a rash, or feel unwell during the infusion.
This treatment helps protect your kidneys when there is rapid breakdown of cancer cells.

Evidence & guidelines

Rasburicase is recommended for the management of tumour lysis syndrome and is more effective than allopurinol at controlling urate, as shown in randomised trials.

Reference: Cairo-Bishop TLS Criteria; NICE Haematology Guidelines; SPC Fasturtec; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

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