Varenicline is highly selective and binds more potently to the α 4β 2 receptor subtype (Ki=0.15 nM) than to other common nicotinic receptors (α 3β 4 Ki=84 nM, α 7 Ki= 620 nM, α 1βγδ Ki= 3,400 nM), or to non-nicotinic receptors and transporters (Ki > 1µM, except to 5-HT3 receptors: