Antifungal drugs
Drugs that are used to treat infections caused by fungi (including yeasts).
The most common fungal infections are tinea (ringworm) and candidiasis (thrush).
Tinea is caused by fungi called dermatophytes, which feed on keratin (the principal protein of the skin, hair, and nails).
Tinea most commonly affects the skin between the toes (athlete's foot), the scalp, the skin beneath a beard, the groin, and the nail bed (where it can be deep-seated).
Thrush is caused by overgrowth of the yeast Candida albicans, normally a harmless inhabitant of the gastrointestinal tract and vagina.
This can occur when the normal balance of the body's microorganisms is upset, for example in people taking drugs (e.g. antibiotics, oral contraceptives), or when the body's resistance to infection is lowered, for example in people with diabetes and pregnant women.
The infection is usually confined to the mouth, vagina, or skin folds (it can infect napkin rash in babies), but in severely immunocompromised people (for example those whose immune systems are impaired by AIDS) candidiasis can spread throughout the body. Such people are also susceptible to other systemic fungal infections (e.g. Cryptococcus neoformans).
A variety of drugs is available for treating fungal infections; some of them are also active against bacteria. Many of them act on the cell walls of fungi to make them permeable so that the contents of the cell leak out and the fungus dies.
The imidazole antifungal drugs are used mainly to treat candidiasis (especially of the vagina) and various forms of tinea;
they are usually applied locally (as pessaries, creams, powders, etc.), although some can also be taken orally for treating persistent infections (Diflucan).
The triazoles are usually taken orally.
Other antifungal drugs include griseofulvin and terbinafine (usually taken orally for treating tinea) and nystatin.
For treating deep-seated or systemic infections, such drugs as amphotericin and fluconazole are administered by injection; flucytosine is used specifically for treating systemic yeast infections.
Antifungal drugs applied topically rarely cause side effects, but treatment by mouth or injection may produce severe adverse effects and must be monitored carefully.
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Diflucan
