Reversible Cholinesterase Inhibitors

Question 1

Neostigmine
MOA

Answer 1

It reversibly inhibits the action of acetylcholinesterase by preventing it from breaking down ACh into choline and acetate, so potentiates transmitter action. It does this by binding to the anionic site and ester group in the enzyme. The structure of Neostigmine is different enough from ACh (has an aromatic ring) so that it is not metabolized by acetylcholinesterase. Making it an effective inhibitor

Question 2

Neostigmine
Abs/Distrb/Elim

Answer 2

• Given i.v. to reverse neuromuscular block
• By mouth for Myasthenia gravis
• Mostly ionized to low oral bioavailability and poor penetration of the BBB
• Half-life of 1 hr

Question 3

Neostigmine
Clinical use

Answer 3

• Myasthenia gravis
• Reversal of non-depolarising neuromuscular block
• Post-operative urinary retention

Question 4

Neostigmine
Adverse Effects

Answer 4

• May exacerbate asthma
• Unwanted cholinomimetic actions can be reduced by atropine