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': "Out of two anticholinesterases, drug 'X' is a teiary amine while drug 'Y' is a quaernary ammonium compound. Then \nSelect and explain. \nA. Drug 'X' is likely to be more potent than 'Y', B. Drug 'Y' will produce CNS effects, C. Drug 'Y' will be completely metabolized in the body, D. Drug 'X' will be more suitable to be used as a miotic", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Drug X is physostigmine and Drug Y is neostigmine. Physostigmine:- It is rapidly absorbed from g.i.t. and parenteral sites. Applied to the eye, it penetrates cornea freely. It crosses blood-brain barrier and is disposed after hydrolysis by ChE. Neostigmine and congeners:- These are poorly absorbed orally; oral dose is 20-30 times higher than parenteral dose. They do not effectively penetrate cornea or cross blood-brain barrier. They are paially hydrolysed and paially excreted unchanged in urine. Ref:- kd tripathi; pg num:-107,108', 'role': 'assistant'}]