Muscle relaxants

Question 1

Mechanism of action of suxamethonium

Answer 1

• Depolarising neuromuscular blocker
• Inhibits action of acetylcholine at the neuromuscular junction

Question 2

What compounds degrade suxamethonium in the neuromuscular junction?

Answer 2

• plasma cholinesterase
• acetylcholinesterase

Question 3

Advantages of suxamethonium

Answer 3

Fastest onset and shortest duration

Question 4

Adverse effects of suxamethonium

Answer 4

• hyperkalaemia
• malignant hyperthermia
• lack of acetylcholinesterase

Question 5

Atracurium, Pancuronium and Vecuronium are Non-depolarising neuromuscular blocks. TRUE/FALSE?

Answer 5

TRUE

Question 6

Duration of action of Atracurium and vecuronium

Answer 6

30-45 minutes

Question 7

Adverse effects of atracurium

Answer 7

Generalised histamine release on administration may produce facial flushing, tachycardia and hypotension

Question 8

Adverse effects of atracurium

Answer 8

Generalised histamine release on administration may produce facial flushing, tachycardia and hypotension

Question 9

How is Atracurium excreted by the body?

Answer 9

• Not excreted by liver or kidney - broken down in tissues by hydrolysis

Question 10

Reversal agent for atracurium, pancuronium and vecuronium

Answer 10

Neostigmine

(effects of pancuronium may only be partially reversed)

Question 11

What is the main difference between atracurium and vecuronium?

Answer 11

Vecuronium degraded by liver and kidney
Atracurium broken down in tissues via hydrolysis

Question 12

Onset and duration of action of pancuronium

Answer 12

Onset approx. 2-3 minutes
Duration of action up to 2 hours