Antifungal drug
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An antifungal drug is medication used to treat fungal infections such as athlete's foot, ringworm and candidiasis (thrush), as well as serious systemic infections like cryptococcal meningitis.
Unlike bacteria, yeasts and fungi are eukaryotes, as are humans (and all other plants and animals). The basic structure of a fungal cell is nearly identical to a human's. This means finding a target for an antifungal to attack, that does not exist in the infected organism, is more difficult.
List of antifungal drugs
Antifungals work by exploiting differences between mammalian and fungal cells to kill off the fungal organism and without significantly harming the host. There are often side-effects to these drugs.
There are several classes of antifungal drugs.
The polyenes bind with sterols in the fungal cell wall, principally ergosterol. This causes the cell's contents to leak out and the cell dies. Human (and other animal) cells contain cholesterol rather than ergosterol so are much less suceptible.
The imidazole and triazole groups of antifungal drugs inhibit the enzyme cytochrome P450 14α-demethylase. This enzyme converts lanosterol to ergosterol, and is required in fungal cell wall synthesis. These drugs also block steroid synthesis in humans.
Imidazoles:
- Miconazole
- Ketoconazole
- Clotrimazole
- Econazole
- Mebendazole
- Bifonazole
- Butoconazole
- Fenticonazole
- Isoconazole
- Oxiconazole
- Sertaconazole
- Sulconazole
- Thiabendazole
- Tiaconazole
The triazoles are newer, and are less toxic and more effective:
Allylamines inhibit the enzyme squalene epoxidase, another enzyme required for ergosterol synthesis:
Echinocandins inhibit the synthesis of glucan in the cell wall, probably via the enzyme 1,3-β glucan synthase:
Others:
- Flucytosine is an antimetabolite.
- Griseofulvin binds to polymerized microtubules and inhibits fungal mitosis.