(1R,1’R,2R,2’S)-2,2′-((pentane-1,5-diylbis(oxy))bis(3-oxopropane-3,1-diyl))bis(1-(3,4-dimethoxybenzyl)-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinolin-2-ium) is an impurity of Cisatracurium, an enantiomer of a neuromuscular blocking agent.