Everything about Antifungal totally explained
An
antifungal drug is
medication used to treat
fungal infections such as
athlete's foot,
ringworm,
candidiasis (thrush), serious systemic infections such as
cryptococcal meningitis, and others. Such drugs are usually obtained by a doctor's
prescription or purchased
over-the-counter.
List of antifungal drugs
Antifungals work by exploiting differences between mammalian and fungal cells to kill off the fungal organism without dangerous effects on the host. Unlike
bacteria, both
fungi and humans are
eukaryotes. Thus fungal and human
cells are similar at the molecular level. This means it's more difficult to find a target for an antifungal drug to attack that doesn't also exist in the infected organism. Consequently, there are often
side-effects to some of these drugs. Some of these side-effects can be life-threatening if not used properly.
There are several classes of antifungal drugs.
Polyene antifungals
A polyene is a circular molecule consisting of a hydrophobic and hydrophilic region. This makes polyene an amphoteric molecule. The
polyene antimycotics bind with
sterols in the fungal
cell membrane, principally
ergosterol. This changes the transition temperature (Tg) of the cell membrane, thereby placing the membrane in a less fluid, more crystalline state. As a result, the cell's contents leak out (usually the hydrophilic contents) and the cell dies. Animal cells contain
cholesterol instead of ergosterol and so they're much less susceptible. (Note: as polyene's hydrophobic chain is reduced, its sterol binding activity is increased. Therefore, increased reduction of the hydrophobic chain may result in it binding to cholesterol, making it toxic to animals.)
Imidazole and triazole antifungals
The
imidazole and
triazole antifungal drugs inhibit the
enzyme cytochrome P450 14α-demethylase. This enzyme converts
lanosterol to ergosterol, and is required in fungal cell membrane synthesis.
These drugs also block
steroid synthesis in humans.
Imidazoles:
Miconazole (Miconazole nitrate)
Ketoconazole
Clotrimazole - marketed as Lotrimin or Lotrimin AF (and Canesten in the UK)
Econazole
Bifonazole
Butoconazole
Fenticonazole
Isoconazole
Oxiconazole
Sertaconazole - marketed as Ertaczo in North America
Sulconazole
Tioconazole
The triazoles are newer, and are less toxic and more effective:
Fluconazole
Itraconazole
Isavuconazole
Ravuconazole
Posaconazole
Voriconazole
Terconazole
Allylamines
Allylamines inhibit the
enzyme squalene epoxidase, another enzyme required for ergosterol synthesis:
Terbinafine - marketed as "Lamisil" in North America, Australia, the UK and Germany.
Amorolfine
Naftifine - marketed as "Naftin" in North America
Butenafine - marketed as Lotrimin Ultra
Echinocandins
Echinocandins inhibit the synthesis of
glucan in the
cell wall, probably via the
enzyme 1,3-β glucan synthase:
Anidulafungin
Caspofungin
Micafungin
Others
Others:
Benzoic acid has antifugal properties but must be combined with a keratolytic agent
Ciclopirox is a fungicidal. Its real name is ciclopirox olamine.
Flucytosine, or 5-fluorocytosine, is an antimetabolite.
Griseofulvin binds to polymerized microtubules and inhibits fungal mitosis.
Gentian Violet
Haloprogin
Tolnaftate is fungicidal, marketed as Tinactin, Desenex, Aftate, as well as other names
Undecylenic acid is fungistatic
Alternatives:
Tea tree oil -- ISO 4730 ("Oil of Melaleuca, Terpinen-4-ol type")
Citronella oil
lemon grass
orange oil
palmarosa oil
patchouli
lemon myrtle
Neem Seed Oil
Coconut Oil -- medium chain triglycerides in the oil have antifungal activities
Zinc dietary supplements or natural food sources, including pumpkin seeds and chick peas
Selenium dietary supplements or natural food sources, particularly Brazil nuts
Dandruff shampoos
Antifungal drugs are often found in dandruff shampoos. Among the most common are pyrithione zinc,selenium sulfide and ketoconazole (Nizoral).
Further Information
Get more info on 'Antifungal'.
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