Griseofulvin acts on dermatophytes by which mechanism, and which property explains its interaction with warfarin?
- A Inhibits squalene epoxidase; it displaces warfarin from albumin
- B Disrupts ergosterol membranes; it competes for the same CYP2C9 pathway
- C Inhibits fungal mitosis by binding tubulin; it induces hepatic CYP450 enzymes accelerating warfarin clearance ✓
- D Inhibits thymidylate synthase; it antagonises vitamin K absorption
Correct answer: C. Inhibits fungal mitosis by binding tubulin; it induces hepatic CYP450 enzymes accelerating warfarin clearance
Explanation
Griseofulvin binds fungal microtubular protein, disrupting mitotic spindle function and halting metaphase, so it is active only against dermatophytes and deposits in keratin precursor cells of skin, hair and nails. It is a classical inducer of hepatic cytochrome P450 enzymes, which accelerates warfarin metabolism and reduces INR control, requiring dose adjustment. Displacement interactions and shared CYP2B9 competition describe other drug classes, not griseofulvin.
Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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