Which statement about glycopyrrolate is true?

Which statement about glycopyrrolate is true?

• A. It crosses the blood-brain barrier
• B. It does not cross the blood-brain barrier
• C. It is a cholinesterase inhibitor
• D. It increases salivation

Answer: (B)

Glycopyrrolate is a quaternary ammonium antimuscarinic drug, which means it blocks muscarinic receptors peripherally but does not readily enter the central nervous system. Its charged, nonlipid-soluble structure prevents it from crossing the blood-brain barrier, so it provides the desired effects—drying secretions and reducing salivation—without central (brain) effects. It is not a cholinesterase inhibitor, so it doesn’t increase acetylcholine levels; instead, it blocks muscarinic receptors. Because it acts peripherally, it lowers secretions rather than increasing them, which is why the true statement is that it does not cross the blood-brain barrier. If a drug did cross the BBB more readily (like atropine, which is less charged and more lipid-soluble), central effects such as confusion or delirium could occur.

Glycopyrrolate is a quaternary ammonium antimuscarinic drug, which means it blocks muscarinic receptors peripherally but does not readily enter the central nervous system. Its charged, nonlipid-soluble structure prevents it from crossing the blood-brain barrier, so it provides the desired effects—drying secretions and reducing salivation—without central (brain) effects. It is not a cholinesterase inhibitor, so it doesn’t increase acetylcholine levels; instead, it blocks muscarinic receptors. Because it acts peripherally, it lowers secretions rather than increasing them, which is why the true statement is that it does not cross the blood-brain barrier. If a drug did cross the BBB more readily (like atropine, which is less charged and more lipid-soluble), central effects such as confusion or delirium could occur.