Pharmacology

Question 1

What is the action of neostigmine and what are its key uses?

Answer 1

Neostigmine binds the active site of acetylcholinesterase so the enzyme can no longer break down ACh, indirectly stimulates both nicotinic & muscarinic receptors

USES
o Myasthenia gravis = improve muscle tone
o Reverse effects of non-depolarising (competitive) muscle relaxants eg. rocuronium and vecuronium o Conservative management of acute colonic pseudo-obstruction
o Urinary retention without mechanical obstruction

Question 2

How do we group neuromuscular blockade agents? What are some examples of each subgroup?

Answer 2

NON DEPOL (Competitive)

• Combines with nicotinic receptors on the muscle end-plate of the neuromuscular junction
• competitively block the action of ACh (therefore can be reversed by neostigmine)
• include pancuronium, vecuronium and rocuronium

DEPOLARISING (non-competitive)

• mimics the action of ACh on nicotinic receptors, resulting in depolarization
• brief period of fasciculation, followed by neuromuscular blockade and flaccid paralysis
• suxamethonium