Mupirocin calcium Imp. D (EP): 9-[[(2E)-4-[(2R,3aS,6S,7S)-2-[(2S,3S)-1,3-dihydroxy-2-methylbutyl]-7-hydroxyhexahydro-4H-furo[3,2-c]pyran-6-yl]-3-methylbut-2-enoyl]oxy]nonanoic acid.