Vesamicol can be broadly categorized as a cholinergic physiological antagonist, because it reduces the apparent activity of cholinergic neurons, but does not act at the postsynaptic ACh receptor. Vesamicol causes a non-competitive and reversible block of the intracellular transporter VAChT responsible for carrying newly synthesized ACh into secretory vesicles in the presynaptic nerve terminal. This transport process is driven by a proton gradient between cell organelles and the cytoplasm. Blocking of acetylcholine loading leads to empty vesicles fusing with neuron membranes, decreasing ACh release.
^Salin-Pascual RJ, Jimenez-Anguiano A (October 1995). "Vesamicol, an acetylcholine uptake blocker in presynaptic vesicles, suppresses rapid eye movement (REM) sleep in the rat". Psychopharmacology121 (4): 485–7. doi:10.1007/BF02246498. PMID8619013.