Amphotericin is an antifungal medication used for serious fungal infections. Amphotericin is known in two forms: amphotericin A and amphotericin B. Because of its higher in vivo antifungal activity, the latter is used clinically and in cell culture to avoid fungi and yeast contamination. Amphotericin B binds with ergosterol, a component of fungal cell membranes, forming pores that cause rapid leakage of monovalent ions and subsequent fungal cell death.