(Amphotericin-B, Azoles, Polyenes)
Cytoplasm of each living cell is bounded by cytoplasmic membrane, which serves as a selective permeability barrier and performs active transport functions. By performing such vital functions, cell membrane controls the internal composition of the cell. If the functional integrity of cell membrane is interrupted, macromolecules and ions escape from the interiors of the cells resulting in damage or death of the cell.
Selectivity of chemotherapeutic agents is due to effect that cytoplasmic membrane of certain bacteria and fungi can be more readily disrupted by some agents than cell membrane of humans and animal cells. Example of this mechanism is that polymyxins are active against Gram-negative bacteria and Polyenes antibiotics (Amphotericin) are acting of fungi. However polymyxins are inactive against fungi and Polyenes are inactive against bacteria. This is because ergosterol is present in the cell membrane of fungi and absent in bacterial cell membrane. Polyenes (drugs acting against fungi) require ergosterol to be present in cell membrane to exert their effects that’s why they are active against fungi and not active against bacteria.
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