Acetylethylcholine mustard hydrochloride is a choline acetyl-transferase inhibitor that decreases muscle contraction frequency by inhibiting the synthesis of acetyl-beta-methylcholine (Ach), with a half-maximal inhibitory concentration (IC50) of 1.22 mM. It serves as an irreversible ligand for the high-affinity choline transport system and functions as a specific presynaptic long-acting cholinergic toxin. Additionally, acetylethylcholine mustard hydrochloride is a precursor to the ethylcholine mustard aziridinium ion.