Amphotericin B is a type of antifungal drug used to treat a wide range of fungal and/or yeast (sour crop) infections---systemic or topical. It is effective against Aspergillus fumigatus, Coccidioides immitis, Cryptococcus neoformans, Histoplasma capsulatum, Rhodotorula, Blastomyces dermatitidis, Mucor mucedo, and Sporothrix schenckii. While Candida albicans is generally quite susceptible to amphotericin B, non-albicans species may be less susceptible.
Amphotericin B acts by binding to sterols (ergosterol) in the cell membrane of susceptible fungi. This creates a transmembrane channel, and the resultant change in membrane permeability allowing leakage of intracellular components. Ergosterol, the principal sterol in the fungal cytoplasmic membrane, is the target site of action of amphotericin B and the azoles.
Form: Amphotericin B is available as an injectable solution (5 mg/ml) for slow (over a period of several hours) IV administration, in sinus flushes, intratracheally, or nebulized in conjunction with another antifungal drug. There is also a lotion or cream (3%) available that is often used for fungal dermatitis or oral candidiasis that is resistant to nystatin. If Amphotericin B is applied topically, it can be very irritating and so needs to be diluted in water.
If administered rapidly or if overdosed, can result in heart arrhythmias and cardio-respiratory arrest. Since the drug is eliminated by the kidneys, it has a high risk of causing kidney damage (nephrotoxicity) and thus should only be used for a short duration.