Final answer:
Triazoles and allylamines are antifungals that inhibit ergosterol synthesis and are used to treat systemic yeast and topical skin infections, respectively. They are effective because they selectively target a component of fungal cell membranes without affecting human cells.
Step-by-step explanation:
The antifungals that work by inhibiting ergosterol synthesis include the triazoles and the allylamines. Triazoles, such as fluconazole, are known to inhibit ergosterol biosynthesis and can be used to treat several types of systemic yeast infections. They have the advantage of more selective toxicity, which results in fewer side effects. Similarly, allylamines like terbinafine inhibit an earlier step in ergosterol biosynthesis and are commonly used topically for dermatophytic skin infections as well as orally for nail fungus treatment.
Disruption of ergosterol biosynthesis is an effective mode of action for antifungals because this pathway is specific to fungi. Since ergosterol is a component of fungal cell membranes, but not of human cell membranes (which contain cholesterol), drugs targeting this process can be selectively toxic to fungi without harming human cells.