This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: A.N.S., Subject name: Pharmacology
Which of the following drugs does not cross blood placental barrier? 
Select and explain. 
A. Atropine, B. Glycopyrrolate, C. Physostigmime, D. Hyoscine hydro bromide
B: Glycopyrrolate
Answer: B: Glycopyrrolate 
Explanation: Ans. (B) Glycopyrrolate(Ref: KDT 8th/e p124)Glycopyrrolate is a quarternary ammonium compounds and is thus water soluble and unable to penetrate BBB.