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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Neostigmine is not able to cross blood brain barrier because of its
assistant
The correct answer is  Quaternary ammonium compounds are water soluble and thus cannot cross blood brain barrier neostigmine is a quaternary derivatives where as physostigmine is a teritiary amine Ref-KDT 6/e p101