This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anesthesia, Subject name: Pharmacology
[{'content': 'Which of the following drug do not cross the blood-brain barrier? \nSelect and explain. \nA. Diacetyl monoxime, B. Obidoximine, C. Physostigmine, D. Neostigmine', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Neostigmine being a quaternary ammonium compound and highly polar cannot cross BBB.Pralidoxime which is used in OP poisoning also can&;t cross the BBB.Ref: Katzung 11th ed.Pg 121', 'role': 'assistant'}]