Nystatin Mechanism — MFDS Part 1 MCQ
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Correct answer: A — Binding to membrane ergosterol and forming permeability-altering pores
Nystatin is a polyene antifungal that interacts preferentially with ergosterol in the fungal cell membrane. This promotes pore formation and membrane disruption, increasing permeability and causing leakage of intracellular constituents. Oral nystatin acts locally because gastrointestinal absorption is negligible. Inhibition of lanosterol 14-alpha-demethylase is the mechanism of azoles such as fluconazole. Beta-1,3-D-glucan synthase is inhibited by echinocandins, whereas squalene epoxidase is inhibited by allylamines such as terbinafine. Disruption of fungal microtubules and the mitotic spindle is associated with griseofulvin. Therefore, the best answer is A.
Reference: Récamier KS et al. Effect of membrane structure on the action of polyenes: I. Nystatin action in cholesterol- and ergosterol-containing membranes. Journal of Membrane Biology. 2010;237:31–40. https://pubmed.ncbi.nlm.nih.gov/20872217/