Neuromuscular Blockers

Question 1

Which chemical do all NMBs resemble?

Answer 1

acetylcholine

Question 2

Name the only depolarizing NMB on the market. What enzyme degrades it? Is this enzyme found in the synaptic cleft?

Answer 2

Succinylcholine. Degraded by pseudocholinesterase aka butyrylcholinesterase. Not found in the cleft in high amounts.

Question 3

Which type of NMB competes with Ach for the receptor?

Answer 3

Non-depolarizing NMBs are competitive.

Question 4

What are the two types of non-depolarizing NMBs?

Answer 4

Amino steroid derivatives and benzylisoquinoline derivatives

Question 5

Name the three amino steroid derivatives and the two benzylisoquinoline derivatives.

Answer 5

Amino steroids: pancuronium, rocuronium, vecuronium.

Benzylisoquinoline derivatives: atracurium, cistracurium.

Question 6

NMBs work on ________ Ach receptors.

Answer 6

nicotinic

Question 7

Briefly describe the mechanism of action of non-depolarizing NMBs.

Answer 7

They competitively block nicotinic Ach receptors to prevent Ach from binding, causing flaccid paralysis.

Question 8

___% blockage of Ach nicotinic receptors is needed for paralysis from non-depolarizing NMBs.

Answer 8

70%

Question 9

Depolarizing NMBs cause _______ paralysis during phase 1 and _______ paralysis during phase 2.

Answer 9

spastic during phase 1 and flaccid during phase 2

Question 10

What is the primary clinical use for depolarizing NMBs? Why?

Answer 10

For intubation because they are fast acting and wear off fast

Question 11

Which two non-depolarizing NMBs are cleared organ-independently?

Is succinylcholine metabolized in an organ independent manner?

Answer 11

Atracurium and cistracurium are metabolized organ-independently.

Succinylcholine is organ-independent, too.

Question 12

Describe the sequence of paralysis for NMBs.

Answer 12

Small muscles first, large muscles last

Question 13

What type of NMBs are often used during hypothermia protocol?

Answer 13

Non-depolarizing NMBs

Question 14

Which NMB is the longest acting?

Answer 14

Pancuronium

Question 15

Amino-steroid derivative NMBs are dependent on these two organs for metabolism.

Answer 15

Liver, kidneys

Question 16

Which NMBs are deactivated via spontaneous Hofmann elimination reactions in vivo?

Answer 16

Benzylisoquinoline derivatives

Question 17

What type of NMBs have the following AEs: Bradycardia, Masseter muscle rigidity, hyperkalemia, malignant hyperthermia, muscle pain, anaphylaxis, increased intragastric pressure, increased intra-ocular pressure.

Answer 17

Depolarizing NMB

Question 18

Butyrylcholinesterase deficiency would be a contraindication to using which specific NMB?

Answer 18

Succinylcholine

Question 19

Name the medication, when taken concomitantly, increases risk for acute quadriplegic myopathy syndrome.

Answer 19

Steroids

Question 20

Name four drugs that increase (potentiate) NMB blockade.

Answer 20

1. General (inhaled) anesthetics
2. Antibiotics
3. Calcium channel blockers
4. Local anesthetics

Question 21

What train-of-four values are “ideal” for surgical procedures and what percentage of receptors blocked correspond to each value?

Answer 21

2/4 twitches = 85% blocked
1/4 twitches = 90% blocked
this is ideal

Question 22

How are non-depolarizing NMBs reversed clinically?

How are depolarizing NMBs reversed clinically?

Answer 22

Acetylcholinesterase inhibitors are given for non-depolarizing NMBs.

Depolarizing NMBs cannot be reversed clinically right now.

Question 23

Name an AE that pancuronium and some rocuroniums may cause.

Answer 23

Tachycardia, which leads to hypertension.

Question 24

Name two AEs that atracurium might cause.

Answer 24

1. Histamine release and all the garbo that comes along with that.
2. Tachycardia and seizure-like activity from the metabolite laudanosine.

Question 25

What is Acute Quadriplegic Myopathy Snydrome (AQMS)? What NMBs can cause it? Concomitant use of which drugs increase risk for this?

Answer 25

Residual and prolonged paralysis from the NMB lasting days to weeks. Non-depolarizing NMBs can cause it. Higher risk with concomitant steroid use.

Question 26

Which non-depolarizing NMB has the fastest onset?

Answer 26

Rocuronium.