Polymyxin B6 Sulfate

(3R,6S) -N- ((2S) -4-amino-1- (((3R) -1- (((2S) -4-amino-1-oxo-1- (((6R,9R,12R,15R,18R) -6,9,18-tris (2-aminoethyl) -15-benzyl-3- ((R) -1-hydroxyethyl) -12-isobutyl-2,5,8,11,14,17,20-heptaoxo-1,4,7,10,13,16,19-heptaazacyclotricosan-21-yl) amino) butan-2-yl) amino) -3-hydroxy-1-oxobutan-2-yl) amino) -1-oxobutan-2-yl) -3-hydroxy-6-methyloctanamide