atracurium

noun

at·​ra·​cu·​ri·​um ˌa-trə-ˈkyu̇r-ē-əm 

: a muscle relaxant administered intravenously in the form of its besylate C₆₅H₈₂N₂O₁₈S₂ especially in conjunction with general anesthesia to facilitate insertion of an endotracheal tube or to relax skeletal muscles during surgery or mechanical ventilation

Note: Atracurium counteracts the action of the neurotransmitter acetylcholine at neuromuscular junctions by binding to the same receptors it acts upon.