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.
List of antifungal drugs
Antifungals work by exploiting differences between mammalian and fungal cells to kill off the fungal organism without significantly harming the host. Unlike bacteria, both fungi and humans are eukaryotes. The basic structure of a fungal cells and human cells are nearly identical. This means it is more difficult to find a target for an antifungal medication to attack that does not also exist in the infected organism. Consequently, there are often side-effects to these drugs.
There are several classes of antifungal drugs.
The polyene antibiotics bind with sterols in the fungal cell wall, principally ergosterol. This causes the cell's contents to leak out and the cell dies. Animal cells contain cholesterol instead of ergosterol and so they are much less susceptible.
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.
Dandruff shampoos
Antifungal drugs are often found in dandruff shampoos. Among the most common are pyrithione zinc and selenium sulfide.