The antifungal action of terbinafine results from inhibition of which enzyme?
- A Squalene epoxidase ✓
- B 14-alpha-demethylase
- C Beta-1,3-glucan synthase
- D Thymidylate synthase
Correct answer: A. Squalene epoxidase
Explanation
Terbinafine is an allylamine that blocks squalene epoxidase, an early step in ergosterol biosynthesis. This causes squalene accumulation, which is toxic to the fungal cell, making terbinafine fungicidal against dermatophytes. The azoles act later in the pathway at lanosterol 14-alpha-demethylase, while echinocandins target glucan synthesis in the cell wall. Terbinafine is first line for dermatophyte onychomycosis.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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