biology

Rasburicase

Rasburicase is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Rasburicase rather than just read about it. In short: Rasburicase, sold under the brand name Elitek in the US and Fasturtec in the EU, is a medication that helps to clear uric acid from the blood. It is a recombinant version of urate oxidase, an enzyme that metabolizes uric acid to allantoin.

Key takeaways

Rasburicase belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Rasburicase to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Rasburicase from memory before moving on to harder problems.

Reference excerpt

Rasburicase, sold under the brand name Elitek in the US and Fasturtec in the EU, is a medication that helps to clear uric acid from the blood. It is a recombinant version of urate oxidase, an enzyme that metabolizes uric acid to allantoin. Urate oxidase is known to be present in many mammals but does not naturally occur in humans. Rasburicase is produced by a genetically modified Saccharomyces cerevisiae strain. The complementary DNA (cDNA) coding for rasburicase was cloned from a strain of Aspergillus flavus. Rasburicase (Q00511) is a tetrameric protein with identical subunits. Each subunit is made up of a single 301 amino acid polypeptide chain with a molecular mass of about 34 kDa. The drug product is a sterile, white to off-white, lyophilized powder intended for intravenous administration following reconstitution with a diluent. Elitek (rasburicase) is supplied in 3 mL and 10 mL colorless, glass vials containing rasburicase at a concentration of 1.5 mg/mL after reconstitution. It is on the World Health Organization's List of Essential Medicines.

Medical uses Rasburicase is approved for use by the U.S. Food and Drug Administration (and European counterparts) for the prevention and treatment of tumor lysis syndrome (TLS) in people receiving chemotherapy for hematologic cancers such as leukemias and lymphomas. However, it is not clear if it results in important benefits such as decreased kidney problems or decreased risk of death as of 2017. It is being investigated for treating severely high blood levels of uric acid from other sources. For example, it has been used for hyperuricemia in gout, in other rheumatologic conditions, and in rhabdomyolysis with kidney failure.

Contraindication Rasburicase use is contraindicated in patients with a G6PDH deficiency as it may cause sudden, severe hemolysis. The blood smear revealed numerous abnormal red blood cells (RBCs) with membranous defects (bite cells) and submembranous blister-like structures (blister cells). These cell types are characteristic of Heinz body hemolytic anemia (HBHA). While Heinz bodies are not visible on a Giemsa-stained smear, they can be detected with supravital staining, appearing as 1- to 3-μm inclusions in RBCs (inset).

Side effects Rasburicase administration can cause anaphylaxis (incidence unknown); methemoglobinemia may occur in susceptible individuals such as those with G6PDH deficiency due to the production of hydrogen peroxide in the urate oxidase reaction. Testing patients for G6PDH deficiency prior to starting a course of rasburicase has been recommended.

Pharmacology

Mechanism of Action In humans, uric acid is the final step in the catabolic pathway of purines. Rasburicase catalyzes enzymatic oxidation of poorly soluble uric acid into an inactive and more soluble metabolite allantoin with carbon dioxide and hydrogen peroxide as byproducts in the chemical reaction.

Pharmacodynamics The measurement of plasma uric acid was used to evaluate the effectiveness of rasburicase in clinical studies. Following administration of either 0.15 or 0.20 mg/kg rasburicase daily for up to 5 days, plasma uric acid levels decreased within 4 hours and were maintained below 7.5 mg/dL in 98% of adult and 90% of pediatric patients for at least 7 days. There was no evidence of a dose response effect on uric acid control for doses between 0.15 and 0.20 mg/kg rasburicase.

Pharmacokinetics The pharmacokinetics of rasburicase were evaluated in both pediatric and adult patients with leukemia, lymphoma or other hematological malignancies. Rasburicase exposure, as measured by AUC0-24 hr and Cmax, tended to increase with a dose range from 0.15 to 0.2 mg/kg. The mean terminal half-life was similar between pediatric and adult patients and ranged from 15.7 to 22.5 hours. The mean volume of distribution of rasburicase ranged from 110 to 127 mL/kg in pediatric patients and from 75.8 to 138 mL/kg in adult patients, respectively. Minimal accumulation of rasburicase ( < 1.3 fold) was observed between days 1 and 5 of dosing. In adults, age, gender, baseline liver enzymes and creatinine clearance did not impact the pharmacokinetics of rasburicase. A cross-study comparison revealed that after administration of rasburicase at 0.15 or 0.20 mg/kg, the geometric mean values of body-weight normalized clearance were approximately 40% lower in Japanese (n=20) than that in Caucasians (n=22).

Society and culture

Economics Rasburicase is much more expensive than the conventional uric acid lowering treatment for tophaceous gout.

References

Illustrations

Worked examples

Example 1 — a first encounter with Rasburicase

Start with the simplest possible case. Write down what Rasburicase claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Rasburicase before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Rasburicase ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Rasburicase

In research: Rasburicase appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Rasburicase in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Rasburicase is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chemotherapeutic adjuvants, World Health Organization essential medicines, so understanding it makes those chapters shorter.
In everyday life: Look for Rasburicase outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Rasburicase in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Rasburicase means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Rasburicase out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rasburicase in simple terms?

Why does Rasburicase matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Rasburicase?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Rasburicase.