Infectious diseases caused by fungi are called mycoses, and they are often chronic in nature. Fungal infections that are most difficult to treat are systemic mycoses, which are often life threatening. They are generally resistant to antibiotics used in the treatment of bacterial infections. Thus, treatment of fungal infections requires special group of antimicrobials termed as antifungals.
Antifungal agent’s also known as antimycotic drugs are pharmaceutical fungicide or fungistatic agent used to treat and prevent mycosis such as athlete’s foot, ringworm, candidiasis (thrush), serious systemic infections such as cryptococcal meningitis and others.
- Fungistatics are anti-fungal agents that inhibit the growth of fungus. E.g. Fluconazole, Itraconazole
- Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. E.g. Hexachlorobenzene
Antifungal agent are drugs that selectively eliminates fungal pathogens from a host with minimal toxicity towards them.
Developing a drug to combat fungal infections leaving the human host unaffected is very difficult. Major reason being nature of fungal diseases: they are eukaryotic species biochemically similar to human.
Both fungal and human cells are eukaryotic in structure, which means that there are few differences that can be exploited in order to achieve selective toxicity towards fungi whilst leaving the human cells unharmed.
This causes some side effects to the host cells thus, minimizing the side effects is also an important factor in antifungal products. It is difficult to find or design drugs that target fungi without affecting human cells (side effects).
They act by exploiting differences between mammalian and fungal cells to kill the fungal organism without dangerous effects on the host.
Antifungal drugs can be systemic or topical with their action being fungistatic or fungicidal.
Many antifungal drugs exhibit marked variability in drug blood concentrations due to Inconsistent absorption, drug interactions, elimination, metabolism, genetic variability etc.
Most antifungal drugs interfere with biosynthesis or integrity of ergosterol, major sterol in the fungal cell membrane. Others cause disruption of the fungal cell wall.
Classes of Anti-Fungals: Antifungal agents can be classified on various basis such as infections they treat, chemical composition and their mode of action.
Antifungal Agents can be classified into two groups based on the infections they inhibit or treat.
- Systemic: Drugs employed for treatment of systemic mycoses E.g. Amphotericin B, Fluconazole, Ketoconazole, and Itraconazole.
- Topical: Agents used against superficial fungal infections. E.g. Clotrimazole, Miconazole, Nystatin.
Based on their mechanism of action, they can be grouped into five classes:
- Other agents (Griseofulvin and Flucytosine).
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