Final answer:
Amphotericin B is a polyene antifungal agent that binds to ergosterol in fungal cell membranes, creating pores that result in increased permeability and leakage of ions, leading to cell death. It is effective against a wide range of systemic fungal infections but has notable nephrotoxic side effects.
Step-by-step explanation:
The polyene antifungal agent that acts by binding to ergosterol in fungal membranes, altering permeability and causing an increase in the leakage of ions such as Na+, K+, and H+, is amphotericin B. This drug creates pores in the fungal cell membranes because ergosterol is a key component of fungal membranes, while human cells contain cholesterol. The disruption of the cell membrane by amphotericin B is an effective mode of action because it results in a loss of essential ions and molecules, leading to cell death. Because of its wide range of activity against systemic fungal infections such as aspergillosis and cryptococcal meningitis, it has been a staple antifungal treatment for many years. However, its use can be limited by the occurrence of serious side effects, including nephrotoxicity.