Colchicine is used in acute gout flares. Its mechanism of action is:
- A Inhibition of xanthine oxidase, reducing uric acid synthesis
- B Selective blockade of IL-1beta receptor on synovial macrophages
- C Binding to tubulin dimers, preventing microtubule polymerisation and inhibiting neutrophil migration and crystal phagocytosis ✓
- D Competitive inhibition of URAT-1 transporter, increasing renal uric acid excretion
Correct answer: C. Binding to tubulin dimers, preventing microtubule polymerisation and inhibiting neutrophil migration and crystal phagocytosis
Explanation
Colchicine binds non-covalently to tubulin heterodimers, preventing their polymerisation into microtubules. This disrupts cytoskeletal function in neutrophils, impairing their chemotaxis, adhesion, phagocytosis of urate crystals, and release of inflammatory mediators. It also inhibits NLRP3 inflammasome activation and IL-1beta processing. The result is a profound anti-inflammatory effect in gout without lowering serum uric acid. Xanthine oxidase inhibition is the mechanism of allopurinol.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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