This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Which of the following anticholinergic agent does not cross the blood brain barrier? 
Select and explain. 
A. Glycopyrrolate, B. Atropine, C. Hyoscine butylbromide, D. Hyoscine hydrobromide
D: Hyoscine hydrobromide
Answer: D: Hyoscine hydrobromide 
Explanation: Answer- D. Hyoscine hydrobromideGlycopyrrolate is a synthetic quaternary anticholinergic, which doesn't cross the blood brain barrier and completely lacks central effects.