Fungal (真菌)

An antifungal agent is a drug that selectively eliminates fungal pathogens from a host with minimal toxicity to the host.

Classes: 1. Polyene Antifungal Drugs: Amphotericin, nystatin, and pimaricin interact with sterols in the cell membrane (ergosterol in fungi, cholesterol in humans) to form channels through which small molecules leak from the inside of the fungal cell to the outside. 2. Azole Antifungal Drugs: Fluconazole, itraconazole, and ketoconazole inhibit cytochrome P450-dependent enzymes (particularly C14-demethylase) involved in the biosynthesis of ergosterol, which is required for fungal cell membrane structure and function. 3. Allylamine and Morpholine Antifungal Drugs: lylamines (naftifine, terbinafine) inhibit ergosterol biosynthesis at the level of squalene epoxidase. The morpholine drug, amorolfine, inhibits the same pathway at a later step. 4. Antimetabolite Antifungal Drugs: 5-Fluorocytosine acts as an inhibitor of both DNA and RNA synthesis via the intracytoplasmic conversion of 5-fluorocytosine to 5-fluorouracil.