Mupirocin calcium Imp. E (EP): 9-[[(2E)-4-[(2R,3RS,4aS,7S,8S,8aR)-3,8-dihydroxy-2-[(1S,2S)-2-hydroxy-1-methylpropyl]hexahydro-2H,5H-pyrano[4,3-b]pyran-7-yl]-3-methylbut-2-enoyl]oxy]nonanoic acid.