Antifungal drug

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 is more difficult to find a weakness in fungi to attack that does not also exist in human cells - so, if you attack the fungus, you may also attack the human cells the fungus lives on. 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 molecule with multiple conjugated double bonds. A polyene antifungal is a macrocyclic polyene with a heavily hydroxylated region on the ring opposite the conjugated system. This makes polyene antifungals amphiphilic. 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 are much less susceptible. (Note: as a polyene's hydrophobic chain is shortened, 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.)
* Natamycin -- 33 Carbons , binds well to ergosterol.
* Rimocidin
* Filipin -- 35 Carbons, binds to cholesterol (toxic).
* Nystatin
* Amphotericin B
* Candicin

Imidazole and Triazole antifungals

The imidazole and triazole are synthetic 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 toxicFact|date=September 2007 and more effectiveFact|date=September 2007:

Triazoles:

* 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

* Benzoic acid - has antifugal properties but must be combined with a keratolytic agent such as in Whitfield's Ointment [cite book|author=Wilson, Gisvold, Block, Beale|title=Wilson and Gisvold's Textbook of Organic Medicinal and Pharmaceutical Chemistry|isbn=0781734819http://books.google.com/books?id=CIpWhgWV5q0C&pg=RA1-PA234&lpg=RA1-PA234&dq=%22benzoic+acid%22+antifungal+tinea&source=web&ots=nK8OrzL8p3&sig=AIzhJBiDYl1-sffvCRmynMan06Q]

* Ciclopirox - (ciclopirox olamine) a fungicidal, It is most useful against Tinea versicolour [cite web |url=http://faculty.swosu.edu/scott.long/phcl/antifung.htm |title=antifung |format= |work= |accessdate=2008-07-09] .
* Tolnaftate - fungicidal, marketed as Tinactin, Desenex, Aftate, as well as other names.
* Undecylenic acid - organic unsaturated fatty acid derived from natural castor oil, fungistatic as well as anti-bacterial and anti-viral.
* Flucytosine, or 5-fluorocytosine, is an antimetabolite.
* Griseofulvin - binds to polymerized microtubules and inhibits fungal mitosis.

* Haloprogin - discontinued due to the emergence of more modern antifungals with fewer side effects [cite web
last =
first =
authorlink =
coauthors =
title = Haloprogin
work = DrugBank
publisher = University of Alberta
date =Nov 06, 2006
url =http://redpoll.pharmacy.ualberta.ca/drugbank/cgi-bin/getCard.cgi?CARD=APRD01011.txt
format =
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accessdate = 2007-02-17 ] .

=Alternatives [cite journal |author=Pattnaik S, Subramanyam VR, Kole C |title=Antibacterial and antifungal activity of ten essential oils in vitro |journal=Microbios |volume=86 |issue=349 |pages=237–46 |year=1996 |pmid=8893526 |doi= |url=http://cat.inist.fr/?aModele=afficheN&cpsidt=3245986] =

* 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 - zinc dietary supplements or natural food sources, including pumpkin seeds and chick peas.
* Selenium - selenium dietary supplements or natural food sources, particularly Brazil nuts.

Anti-Dandruff shampoos

Antifungal drugs are often found in Anti-dandruff shampoos, the antifungal drugs inhibit the yeast, Malassezia furfur (formerly known as Pityrosporum ovale) which encourage seborrhoeic dermatitis and Tinea versicolor.

ee also

* Fungicide
* Antimicrobial

References

External links

* [http://www.fungalguide.ca/treatments/antifungal_drugs.html Antifungal Drugs] - Detailed information on antifungals from the Fungal Guide written by Drs. R. Thomas and K. Barber