2009A04 Compare and contrast atropine and glycopyrrolate.
Discuss the clinical implications of these differences.

Atropine

Glycopyrrolate

Structure

Tertiary amine

Quaternary amine

Atropine

Glyropyrrolate

Administration

·  20-30mcg/kg bolus ± repeat

·  30-60mcg/kg

Time course

·  Onset 1-2 mins

·  Duration 30 mins

·  Onset 2-3 mins

·  Duration 30 mins (4 hours anti-sialogogue)

Absorption

·  Oral bioav 25%

·  Oral bioav 1-20%

Distribution

·  Crosses blood-brain barrier (BBB)

·  Doesn’t cross BBB

·  V_D 0.2L/kg

Metabolism

·  50%

·  Ester hydrolysis -> tropine, tropic acid, glucuronide etc

·  Minimal

Excretion

·  50%

·  Near 100%

Atropine

Glycopyrrolate

Receptor activity

<2mcg/kg: central effect -> ↓HR

·  Partial agonist

CNS effects

·  ↓PONV

·  Mydriasis

·  Confusion

·  Nil

Peripheral effects

·  ↑HR

·  Dry mouth

·  Flushing, fever

·  Constipation

·  Urinary retention

·  Same

·  (mild ↑HR due to partial agonism)

Reversal pairing

·  Atropine 1.2mg

·  Edrophonium 0.5mg

·  Glycopyrrolate 0.5mg (not 0.4)

·  Neostigmine 2.5mg

Specific use

·  Reversal of neuromuscular blockade

·  Emergency treatment of ↓HR

·  Prevent PONV

·  Treat organophosphate poisoning

·  Reversal of neuromuscular blockade

·  Anti-sialagogue