A patient with chronic gout and tophaceous deposits is treated with pegloticase. The mechanism of pegloticase differs from allopurinol because:

• A Pegloticase inhibits xanthine oxidase irreversibly, whereas allopurinol inhibits it reversibly
• B Pegloticase promotes renal excretion of urate via URAT1 blockade, whereas allopurinol inhibits synthesis
• C Pegloticase blocks NLRP3 inflammasome activation in gouty joints
• D Pegloticase is recombinant uricase (pegylated) that converts uric acid to allantoin, whereas allopurinol inhibits uric acid synthesis ✓

Explanation

Pegloticase is polyethylene glycol (PEG)-conjugated recombinant porcine uricase that converts uric acid into allantoin, which is freely water-soluble and excreted renally. This enzyme-replacement approach dramatically dissolves tophaceous deposits. Allopurinol and febuxostat inhibit xanthine oxidase, reducing uric acid synthesis. Pegloticase is reserved for refractory tophaceous gout because PEG antibodies can develop, neutralizing the drug and causing infusion reactions.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.