This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autonomic nervous system, Subject name: Pharmacology
[{'content': 'Which of the following drug binds only with the anionic site of cholinesterase \nSelect and explain. \nA. Physostigmine, B. Neostigmine, C. Edrophonium, D. Pyridostigmine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Refer kDT 6/e p 105,katzung 11e 104 Physostigmine, neostigmine and pyridostigmine are carbamates by chemical nature, they bind to both esteric site and anionic site where as edrophonium is an alcohol and binds to anionic site only', 'role': 'assistant'}]