Neuromuscular blockers

Question 1

d-tubocurarine (give class, charge and duration of action if known)

Answer 1

Competitive, nondepolarizing neuromuscular blocker. Charged, 20 min - 1 hour

Question 2

Mivacuronium (give class, charge and duration of action if known)

Answer 2

Competitive, nondepolarizing neuromuscular blocker, 20 min - 1 hour

Question 3

Pancuronium (give class, charge and duration of action if known)

Answer 3

Competitive, nondepolarizing neuromuscular blocker, 20 min - 1 hour

Question 4

Vecuronium (give class, charge and duration of action if known)

Answer 4

Competitive, nondepolarizing neuromuscular blocker, 20 min - 1 hour

Question 5

Atracurium (give class, charge and duration of action if known)

Answer 5

Competitive nondepolarizing neuromuscular blocker, 20 min - 1 hour

Question 6

Which competitive, nondepolarizing neuromuscular blocker has different degradation, and how is it different?

Answer 6

Atracurium is stable outside body but partially degraded spontaneously in body (good for patients with renal-hepatic failure)

Question 7

Succinylcholine (give class, charge and duration of action if known)

Answer 7

Depolarizing, desensitizing neuromuscular blocker, charged, around 5 minutes

Question 8

What counters competitive, nondepolarizing neuromuscular blockers?

Answer 8

Acetylcholinesterase inhibitors

Question 9

What metabolizes depolarizing, desensitizing neuromuscular blockers?

Answer 9

Pseudocholinesterase

Question 10

Actions of depolarizing, desensitizing neuromuscular blockers (such as succinylcholine)

Answer 10

1) Mimics action of Ach on Nm receptor, 2) keeps postsynaptic membrane depolarized longer, 3) Desensitizes receptor, making receptor insesitive to Ach after repolarization

Question 11

Botulinus toxin (give class, charge and duration of action if known)

Answer 11

Acetylcholine release inhibitor, very long duration of action

Question 12

Where does botulinus toxin bind?

Answer 12

To a protein in cholinergic nerve terminals which causes Ach release, blocking secretion irreversibly

Question 13

List the duration of action for neuromuscular blockers

Answer 13

Succinylcholine (5 min), d-tubocurarine (20 mins), -iums (20-60 minutes), Botulinus toxin (weeks or months)

Question 14

How is the paralysis induced by succinylcholine different from that induced by d-tubocurarine or botulinus toxin (besides duration)?

Answer 14

Succinylcholine paralysis can begin with muscle fasiculations

Question 15

What neuromuscular blockers affect release of another NT (not Ach) and in what way?

Answer 15

d-Tubocurarine and succinylcholine lead to histamine release

Question 16

What neuromuscular blocking agents affect ganglia activity and in what way?

Answer 16

d-tubocurarine (blocks ganglia) and succinylcholine (stimulates then blocks ganglia).

Question 17

Which competitive, depolarizing neuromuscular blocker causes the least histamine release?

Answer 17

Pancuronium

Question 18

How is sensitivity to neuromuscular blocking agents changed in myasthenia gravis?

Answer 18

Insensitive to succinylcholine, hypersensitive to d-tubocurarine

Question 19

What two agents can cause malignant hyperthermia and what is the treatment?

Answer 19

Halothane and succinylcholine. Treatment is dantrolene

Question 20

What can succinylcholine cause in children?

Answer 20

Cardiac damage (rare but life threatening)