9. Cholinergics 5 - Neuromuscular Blocking Agents

Front 1

What are the 5 Neuromuscular blocking agents?

Back 1

VAMPS
-Vecuronium
-Atracurium
-Mivacurium
-Pancuronium
-Succinylcholine

Front 2

What will NMJ blocking agents do?

Back 2

Paralyze muscles

Front 3

2 general categories of clinical uses for Nm blocking agents:

Back 3

-Surgical (relaxants)
-Nonsurgical

Front 4

3 surgical uses of Nm blockers:

Back 4

-Endotracheal intubation
-Muscle relaxant for surgery
-Maintain controlled ventilation during surgery

Front 5

5 Nonsurgical uses of Nm blockers:

Back 5

-Ventilation during longterm ICU stays
-Reduce Laryngeal or general muscle spasms
-Decrease Tetany in disease/MS
-Diagnose myasthenia gravis
-Reduce spasms during ECT

Front 6

2 categories of Nm blockers:

Back 6

-NonDepolarizing (VAMP)
-Depolarizing (Succinylcholine)

Front 7

How do the Nondepolarizing neuromuscular blockers work?

Back 7

As competitive antagonists - compete with ACh for unoccupied endplate receptors

Front 8

What happens when the competitive Nm antagonists do bind nicotinic ACh receptors?

Back 8

They have no intrinsic activity; nothing happens.

Front 9

What are the 4 competitive Nm antagonists to know?

Back 9

-Mivacurium
-Atracurium
-Vecuronium
-Pancuronium

Front 10

What makes Miva, Atra, Vecu, and Pancu different?

Back 10

Their half life

Front 11

What makes Miva/ATra/Vecu/Pancu similar?

Back 11

All are quaternary nitrogens and cannot penetrate the CNS

Front 12

How many receptors have to be blocked for muscle contraction to begin to be interfered with?

Back 12

70-85%

Front 13

How many receptors have to be blocked for muscle contraction to be fully blocked?

Back 13

90-95%

Front 14

How can Neuromuscular junction blockade by competitive antagonists be reversed?

Back 14

By increasing the concentration of ACh at the NMJ

Front 15

What drugs are used to reverse neuromuscular blockade?

Back 15

AChE inhibitors - keeps more ACh in the synapse to do its job longer.

Front 16

Which 2 specific AChE inhibitors are used to overcome competitive antagonist blockade at the NMJ?

Back 16

-Edrophonium
-Neostigmine

Front 17

What are the 3 ways that VAMPs differ?

Back 17

-Half life
-Side effects
-Route of elimination

Front 18

Of VAMP, which one has a
-short half life
-med half life
-long half life

Back 18

Short = Mivacurium 2-8 min
Med = Atra (20m)/Vecu (50m)
Long = Pancuronium 120 min

Front 19

So for Mivacurium:
-Half life
-Metabolized by
-Side effects

Back 19

Half life = 2-8 min (short)
-Metabolized by pseudocholinesterases in serum
-Sl. BP DECREASE, increased HR, minimal histamine release

Front 20

For Atracurium:
-Half life
-Eliminated by
-Side effects

Back 20

Half life = 20 min (med)
-Metabolized by liver
-Bad if a person has liver disease

Front 21

For Vecuronium:
-Half life
-Eliminated by
-Side effects

Back 21

Half life = 50 min (med)
-Excreted renally
-Bad if patient has renal disease

Front 22

What are the Cardiovascular and histamine releasing effects of Vecuronium and Atracurium like?

Back 22

Minimal

Front 23

For Pancuronium:
-Half life
-Side effects

Back 23

Half life = 120 min - long
-Slightly INCREASES bp
-Slightly increases HR
-Slightly increases histamine

Front 24

Which neuromuscular blocker is an AGONIST/depolarizing?

Back 24

Succinylcholine

Front 25

How does a depolarizing agonist inhibit the neuromuscular junction?

Back 25

By causing a sustained EPP which causes depolarization blockade

Front 26

What is the structure of Succinylcholine?

Back 26

2 acetylcholines joined together

Front 27

What type of nitrogens are on Succinylcholine?

Back 27

Quaternary - thus it can't cross into the CNS

Front 28

What happens to muscles initially when Succinylcholine binds to the NMJ?

Back 28

Muscle fasciculations

Front 29

What happens after depolarization blockade is achieved?

Back 29

Flaccid paralysis

Front 30

What is succinylcholine metabolized by?

Back 30

Pseudocholinesterase - not acetylcholinesterase

Front 31

What is the duration of action for Succinylcholine?

Back 31

Ultra short - 5-10m

Front 32

What makes the duration of action longer for succinylcholine? Why?

Back 32

Liver disease - that's where plasma pseudocholinesterase is made

Front 33

What else can prolong the effects of Succinylcholine greatly?

Back 33

Genetic variation in pseudocholinesterase activity

Front 34

What is Succinylcholine frequently used clinically for?

Back 34

Intubation

Front 35

What does Succinylcholine cause at toxic levels?

Back 35

Prolonged apnea

Front 36

What are 2 side effects of Succinylcholine?

Back 36

-Malignant hyperthermia when used with anesthetics
-Post op pain due to fasciculations

Front 37

Can Succinylchoine toxicity be treated with AchE inhibitors?

Back 37

No; it is not a competitive antagonist like VAMP

Front 38

What are 2 ways that you can treat the COMPETITIVE antagonists if apnea is prolonged?

Back 38

-Increase ACh at the NMJ
-Use AchE inhibitors - Edrophonium or Neostigmine