This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Pharmacology
A 55yr old man with dementia was given a natural alkaloid. Which of the following could it be- 
Select and explain. 
A. Tacrine, B. Donepezil, C. Galantamine, D. Rivastigmine
C: Galantamine
Answer: C: Galantamine 
Explanation: Ans. is 'c' i.e., Galantamine Galantamine: o It is a natural alkaloid which selectively inhibits cerebral acetylcholinesterase and has some direct agonistic action on nicotinic receptors as well. o It has produced cognitive and behavioral benefits in Alzheimer's disease