The new cholinesterase inhibitors for Alzheimer's disease, Part 1: their similarities are different.

Three new cholinesterase inhibitors, donepezil, rivastigmine, and galantamine, all inhibit the enzyme AChE. Rivastigmine also inhibits BuChE, which could lead to additional benefits in late-stage Alzheimer's disease, but also cause more GI side effects at initiation of therapy. Galantamine is also an allosteric modulator of nicotinic receptors, which could lead to additional efficacy for attention and for behaviors mediated by neurotransmitters other than ACh. We are now entering an exciting era where the options for treating the devastating illness Alzheimer's disease are multiplying and creating a foundation upon which new therapies with new mechanisms of action can be built.