Micafungin sodium is the salt of the semi-synthetic cyclic lipopeptide, micafungin, a member of the echinocandin class that was reported in 1999 from Fujisawa in Japan. The sodium salt takes advantage of the aryl sulfate moiety providing improved water solubility and is the preferred salt for pharmaceutical applications. Like all echinocandins, micafungin inhibits the synthesis of β-(1,3)-D-glucan, an essential component of the cell wall of susceptible fungi.