How does amphotericin B achieve its therapeutic effect?

Amphotericin B achieves its therapeutic effect primarily by increasing the permeability of fungal cell membranes. It binds to ergosterol, a key component of fungal cell membranes, forming pores that disrupt the membrane's integrity. This disruption leads to the leakage of cell contents, ultimately resulting in fungal cell death.

The mechanism of action for amphotericin B is particularly effective against a broad range of fungi, including many pathogenic species. Its ability to specifically target ergosterol, which is found predominantly in fungi and not in human cells, allows it to have antifungal activity with relatively low toxicity to human cells.

While the other options mention mechanisms such as inhibiting protein synthesis, preventing replication, or blocking DNA synthesis, these actions pertain to different classes of antifungal agents and do not reflect the unique mechanism by which amphotericin B operates. Thus, the correct answer highlights the distinct approach amphotericin B uses in combating fungal infections through membrane disruption.