Definitions

fungistatic

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.)

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:

The triazoles are newer, and are less toxic and more effective:

Triazoles:

Allylamines

Allylamines inhibit the enzyme squalene epoxidase, another enzyme required for ergosterol synthesis:

Echinocandins

Echinocandins inhibit the synthesis of glucan in the cell wall, probably via the enzyme 1,3-β glucan synthase:

Others

Alternatives

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 bicarbonate (baking soda) Arm & Hammer
Ketoconazole 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 remedy .
Ciclopirox olamine Loprox Show similar efficacy to ketoconazole with a relative increase in subjective symptom relief due to its inherent anti-inflammatory properties.
Piroctone olamine (Octopirox) Nivea Complete Control a replacement for the commonly used compound zinc pyrithione
Zinc pyrithione 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
Tar Neutrogena T/Gel
Tea tree oil

See also

References

External links

  • Antifungal Drugs - Detailed information on antifungals from the Fungal Guide written by Drs. R. Thomas and K. Barber



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