All are cholinergic agents EXCEPT:: (A) Gallantamine, (B) Donepezil, (C) Tacrine, (D) Memantine
Answer is D. Ref: KD Tripathi pharmacology 7th edition (page.no:489) All these drugs are used in Alzheimer's disease. But only A,B,C increase cholinergic activity in Alzheimer's. Memantine is a Glutamate Antagonist.it is an NMDA blocker Examples of direct-acting cholinergic agents include choline esters (acetylcholine, methacholine, carbachol, bethanechol, tacrine) and alkaloids (muscarine, pilocarpine, cevimeline)