(R)-Laudanosine-d3 N-3-((5-Hydroxypentyl)oxy)-3-oxopropyl Benzenesulfonate is the labeled analog of (R)-Laudanosine N-3-((5-Hydroxypentyl)oxy)-3-oxopropyl Benzenesulfonate (L178505), an impurity of Cisatracurium (C496700), an enantiomer of a neuromuscular blocking agent. It could be used in liver transplant patient with safety.