Exam 10: NMJ Blockers

Question 1

3 Non-depolarizing NMJ Blockers

Answer 1

Atracurium
Mivacurium
Rocuronium

Question 2

1 Depolarizing NMJ Blocker

Answer 2

Succinylcholine

Question 3

Where do NMJ Blockers have effects? Where do they not?

Answer 3

At NMJ…

NO CNS effects (don’t cross the BBB)

Question 4

Order of muscles to be paralyzed by NMJ blocker (recovery order?)

Answer 4

1. Small, rapidly moving muscles
2. Limb trunk muscles
3. Intercostals
4. Diaphragm
   They recover in the reverse order

Question 5

Dantrolene

Answer 5

Muscle relaxant (not complete)
Treatment for malignant hyperthermia
Also used to for long-term control of muscle spasms

Question 6

3 botox uses

Answer 6

1. Blepharospasm (involuntary eyelid closing)
2. Strabismus (eye spasms)
3. Wrinkles

Question 7

non-depolarizing NMJ blocker mechanism

Answer 7

Competitive inhibitors of ACh at the NMJ

Question 8

reversal of non-depolarizing NMJ blockers

Answer 8

Cholinesterase inhibitors increase ACh at the NMJ, overcoming the competitive inhibition (Neostigmine)

Question 9

2 side effects of non-depolarizing NMJ blockers

Answer 9

1. Prolonged apnea

2. Histamine release

Question 10

Difference between -Curium and -curonium drugs

Answer 10

• curium: Benzylisoquinonlines (can cause histamine release, but don’t have much vagal-blocking effect)
• curonium: Steroidal NMJ blockers (Can cause tachycardia due to vagal blockade, less prominent in Vecuronium or Rocuronium)

Question 11

Sugammadex

Answer 11

Binds to and inactivates steroidal NMJ blockers (Rocuronium)

Approved in Europe, but not the USA

Question 12

1 Short-acting non-depolarizing NMJ blocker

Answer 12

Mivacurium

Lasts 12-18 minutes

Question 13

Mivacurium

Answer 13

Short acting non-depolarizing NMJ blocker

Metabolized quickly by plasma cholinesterase

Question 14

2 Intermediate-acting non-depolarizing NMJ blockers

Answer 14

rocuronium
Atacurium
30-90 minutes

Question 15

Rocuronium

Answer 15

Rapid onset
Used for rapid induction intubation
Lasts 30-90 minutes

Question 16

Atacurium

Answer 16

Similar to rocuronium in effects, but is not metabolized by the liver
Useful in patients with liver or renal failure

Question 17

1 Long duration non-depolarizing NMJ blocker

Answer 17

Pancuronium

2-3 hours

Question 18

Pancuronium

Answer 18

Used to be used as the 2nd drug in the 3-drug lethal injection protocol

Question 19

Succinylcholine

Answer 19

depolarizing NMJ blocker
fast onset, short duration
used for short procedures (intubation)
Causes fasciculations initially, before paralysis (twitching)
No antidote

Question 20

Succinylcholine mechanism

Answer 20

alters electro-chemical driving force
causes excessive opening of nicotinic ACh receptors, decreasing the electrical driving force and therefore less response to motor neuron activity

Question 21

Phase I succinylcholine

Answer 21

Fast onset (single dose)
Augmented by Neostigmine

Question 22

Phase II succinylcholine

Answer 22

Slow onset (many doses)
Unknown exact mechanism
Neostigmine antagonizes Stage II block

Question 23

Dantrolene mechanism

Answer 23

inhibits Ryanodine receptors

Question 24

Dantrolene side effects

Answer 24

muscle weakness

liver toxicity

Question 25

Botox mechanism

Answer 25

Prevents ACh release at the NMJ

Question 26

Botox side effect

Answer 26

Can cause up-regulation of nicotinic ACh receptors, resulting in increased wrinkling and ptosis