Building on the aforementioned, currently approved drugs for AD rivastigmine, galantamine and donepezil, as well as discontinued tacrine (Figure 1), improve cholinergic neurotransmission by inhibition of acetylcholinesterase (AChE, E.C. 3.1.1.7), enzyme responsible for degradation of ACh.9 Here, ACHE is linked to Alzheimer disease.