A patient receiving neostigmine for reversal of neuromuscular blockade develops severe bradycardia and excessive salivation. The treating anaesthesiologist administers glycopyrrolate instead of atropine. Which property of glycopyrrolate best explains why it is preferred in this context?

• A It is a selective M2 muscarinic receptor antagonist
• B It is a quaternary ammonium compound that does not cross the blood-brain barrier ✓
• C It has a longer duration of action than neostigmine
• D It has intrinsic nicotinic receptor agonist activity

Explanation

Glycopyrrolate is a quaternary ammonium anticholinergic that does not cross the blood-brain barrier, preventing CNS side effects like confusion or agitation seen with atropine (a tertiary amine). It effectively blocks peripheral muscarinic effects of neostigmine such as bradycardia and hypersalivation. Its duration of action roughly matches neostigmine, making it a practical pairing. It has no nicotinic activity or selective M2 antagonism.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.