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
Which of the following drug does not cross the blood-placental barrier? 
Select and explain. 
A. Atropine, B. Glycopyrolate, C. Physostigmine, D. Hyoscine hydro bromide
B: Glycopyrolate
Answer: B: Glycopyrolate 
Explanation: Ref:KD Tripathi pharmacology 7th edition (page.no: 19,116) Placental membranes are lipoidal and allow free passage of lipophilic drugs while restricting hydrophilic drugs. Glycopyrrolate is a quaternary ammonium compound. So it can't cross placenta and brain(BBB). Other drugs can cross the placenta