Zanapezil (TAK-147) free base is a potent, reversible and selective acetylcholine esterase ( AChE ) inhibitor. Zanapezil free base shows a potent and reversible inhibition of AChE activity in homogenates of the rat cerebral cortex ( IC 50 =51.2 nM). Zanapezil free base shows a moderate inhibition of muscarinic M1 and M2 receptor binding with K i values of 234 and 340 nM, respectively. Zanapezil free base can be used for the research of early stages of Alzheimer's disease (AD).