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
True statements about neostigmine are 
Select and explain. 
A. It is a quaternary ammonium compounds, B. It is metabolized by the liver, C. It can cross the blood brain barrier, D. Prominent effect on cardiac muscle
A: It is a quaternary ammonium compounds
Answer: A: It is a quaternary ammonium compounds 
Explanation: (Ref. KDT6/e p101-102; Lee 12/ep217) Neostigmine is a reversible cholinesterase inhibitor.It is a quaernary ammonium compound. (lipid insolube agent), so it does not cross blood-brain-barrie. It is paly hydrolyzed by serum cholinesterase and paly excreted unchanged by the kidneys. It possesses some agonistic action on NM receptors.