Antifungal drug
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. Such drugs can be either prescription drugs or
OTC 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 fungal
cells and human cells is 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. Some of these side-effects can be life-threatening.
There are several classes of antifungal drugs.
Polyene antibiotic
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.
*
Nystatin*
Amphotericin B*
Natamycin*
Rimocidin*
Filipin*
PimaricinImidazole and triazole
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*
TiaconazoleThe triazoles are newer, and are less toxic and more effective:
*
Fluconazole*
Itraconazole*
Ravuconazole*
Posaconazole*
VoriconazoleAllylamines
Allylamines inhibit the
enzyme squalene epoxidase, another enzyme required for ergosterol synthesis:
*
Terbinafine - marketed as
Lamisil in North America and the UK
*
Amorolfine*
Naftifine*
ButenafineEchinocandin
Echinocandins inhibit the synthesis of
glucan in the
cell wall, probably via the
enzyme 1,3-β glucan synthase:
*
Anidulafungin*
Caspofungin*
MicafunginOthers
Others:
*
Flucytosine is an
antimetabolite.
*
Griseofulvin binds to
polymerized
microtubules and inhibits fungal
mitosis.
*
FluocinonideAlternatives:
*
Tea tree oil -- ISO 4730 ("Oil of Melaleuca, Terpinen-4-ol type")
Antifungal drugs are often found in
dandruff shampoos. Among the most common are
pyrithione zinc and
selenium sulfide.
*
Fungicide*
OTC Anti-Fungal Drug Manufacture
