Which antifungal drug class inhibits 14-alpha-demethylase, decreasing ergosterol synthesis?

Which antifungal drug class inhibits 14-alpha-demethylase, decreasing ergosterol synthesis?

• A. Azoles
• B. Echinocandins
• C. Polyenes
• D. Allylamines

Answer: (A)

Inhibiting 14-alpha-demethylase, a fungal cytochrome P450 enzyme, stops the conversion of lanosterol to ergosterol, a critical component of the fungal cell membrane. Without enough ergosterol, the membrane becomes faulty—its permeability and function are disrupted, which hampers fungal growth. This mechanism is characteristic of azoles, which block the enzyme’s active site and prevent demethylation. Other antifungals work differently: allylamines block an earlier step (squalene epoxidase), reducing ergosterol; polyenes bind ergosterol in membranes to form pores; echinocandins inhibit cell wall synthesis by blocking β-1,3-glucan synthase. Therefore, the described class is azoles.

Inhibiting 14-alpha-demethylase, a fungal cytochrome P450 enzyme, stops the conversion of lanosterol to ergosterol, a critical component of the fungal cell membrane. Without enough ergosterol, the membrane becomes faulty—its permeability and function are disrupted, which hampers fungal growth. This mechanism is characteristic of azoles, which block the enzyme’s active site and prevent demethylation. Other antifungals work differently: allylamines block an earlier step (squalene epoxidase), reducing ergosterol; polyenes bind ergosterol in membranes to form pores; echinocandins inhibit cell wall synthesis by blocking β-1,3-glucan synthase. Therefore, the described class is azoles.