Glycopyrrolate Quaternary — FRCA Primary MCQ

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ModeratePharmacology - AutonomicGlycopyrrolate QuaternaryFRCA Primary

Glycopyrrolate is a quaternary ammonium compound. This means it:

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Correct answer: D — Does not cross the blood-brain barrier or placenta

Quaternary ammonium compounds are ionised at physiological pH and cannot cross the BBB or placenta. Atropine is a tertiary amine that crosses both. Glycopyrrolate has a longer duration and causes less tachycardia than atropine.

Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care