Rasburicase is used for tumour lysis syndrome prevention in high-risk patients. It acts by:

• A Inhibiting xanthine oxidase, preventing xanthine conversion to uric acid
• B Alkalinising urine to increase uric acid solubility and renal excretion
• C Inhibiting URAT1 transporter in proximal tubule, preventing uric acid reabsorption
• D Recombinant urate oxidase, converting uric acid to allantoin (more water-soluble) ✓

Explanation

Rasburicase is a recombinant form of urate oxidase (absent in humans, present in other mammals), which converts uric acid to allantoin — a compound 5–10 times more water-soluble that is readily excreted by the kidney. This rapidly lowers serum uric acid within hours, critical for preventing urate nephropathy in tumour lysis syndrome. It is contraindicated in G6PD deficiency because the H2O2 generated as a byproduct causes haemolysis. Allopurinol/febuxostat inhibit xanthine oxidase; probenecid inhibits URAT1.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.