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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.
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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, further 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 that 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 toxiccitation needed and more effectivecitation needed:
Triazoles:
Allylamines
Allylamines inhibit the enzyme squalene epoxidase, another enzyme required for ergosterol synthesis:
- Terbinafine - marketed as "Lamisil" in North America, Australia, the UK, Germany and the Netherlands.
- 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:
Others
- Benzoic acid - has antifugal properties but must be combined with a keratolytic agent such as in Whitfield's Ointment1
- Ciclopirox - (ciclopirox olamine) a fungicidal, It is most useful against Tinea versicolour 2.
- 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 3.
Alternatives4
- 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.
| Active ingredient | Example of product | Comments |
| Sodium bicarbonate5 (baking soda) | Arm & Hammer | |
| Ketoconazole6 | Nizoral, or Fungoral | There is a claim that Nizoral shampoo has hair loss benefits but Nizoral Shampoo does not have FDA approval as a hair loss remedy7 . |
| Ciclopirox olamine | Loprox | Show similar efficacy to ketoconazole with a relative increase in subjective symptom relief due to its inherent anti-inflammatory properties8. |
| Piroctone olamine (Octopirox)9 | Nivea Complete Control10 | a replacement for the commonly used compound zinc pyrithione |
| Zinc pyrithione11 | Head & Shoulders, Johnson and Johnson ZP-11, Clinic All Clear, Pantene Pro V, Sikkai Powder | An antifungal and antibacterial agent, was first reported in the 1930s. |
| Selenium sulfide | Selsun Blue, Vichy Dercos Anti-Dandruff shampoo, other varieties of Head & Shoulders | In USA, 1% strength is available over-the-counter, and a 2.5% strength is also available with a prescription |
| Tar12 | Neutrogena T/Gel | |
| Tea tree oil13 |
See also
References
- ^ Wilson, Gisvold, Block, Beale. Wilson and Gisvold's Textbook of Organic Medicinal and Pharmaceutical Chemistry. ISBN 0781734819. http://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
- ^ "antifung". Retrieved on 2008-07-09.
- ^ "Haloprogin". DrugBank. University of Alberta (Nov 06, 2006). Retrieved on 2007-02-17.
- ^ Pattnaik S, Subramanyam VR, Kole C (1996). "Antibacterial and antifungal activity of ten essential oils in vitro". Microbios 86 (349): 237–46. PMID 8893526, http://cat.inist.fr/?aModele=afficheN&cpsidt=3245986.
- ^ Use of Baking Soda as a Fungicide, By George Kuepper, Raeven Thomas, and Richard Earles, © NCAT November 2001
- ^ McGrath J, Murphy GM (1991). "The control of seborrhoeic dermatitis and dandruff by antipityrosporal drugs". Drugs 41 (2): 178–84. PMID 1709848.
- ^ Nizoral Shampoo as a Hair Loss Remedy? http://www.dermadoctor.com/pages/newsletter198.asp
- ^ Ratnavel RC, Squire RA, Boorman GC (2007). "Clinical efficacies of shampoos containing ciclopirox olamine (1.5%) and ketoconazole (2.0%) in the treatment of seborrhoeic dermatitis". J Dermatolog Treat 18 (2): 88–96. doi:. PMID 17520465.
- ^ Dubini F, Bellotti MG, Frangi A, Monti D, Saccomani L (2005). "In vitro antimycotic activity and nail permeation models of a piroctone olamine (octopirox) containing transungual water soluble technology". Arzneimittel-Forschung 55 (8): 478–83. PMID 16149717.
- ^ http://products2.nivea.com/products.php?page_id=1298&lan=com
- ^ Warner RR, Schwartz JR, Boissy Y, Dawson TL (2001). "Dandruff has an altered stratum corneum ultrastructure that is improved with zinc pyrithione shampoo". J. Am. Acad. Dermatol. 45 (6): 897–903. doi:. PMID 11712036.
- ^ Piérard-Franchimont C, Piérard GE, Vroome V, Lin GC, Appa Y (2000). "Comparative anti-dandruff efficacy between a tar and a non-tar shampoo". Dermatology (Basel) 200 (2): 181–4. doi:. PMID 10773717.
- ^ Prensner R (2003). "Does 5% tea tree oil shampoo reduce dandruff?". The Journal of family practice 52 (4): 285–6. PMID 12681088, http://www.jfponline.com/Pages.asp?AID=1437.
External links
- Antifungal Drugs - Detailed information on antifungals from the Fungal Guide written by Drs. R. Thomas and K. Barber
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