Skeletal Muscle Relaxants

Question 1

What are the two groups of neuromuscular blocking drugs?
What is their MOA?
What is the prototype of each group?

Answer 1

Non depolarizing and depolarizing
Non depolarizing are antagonists to the nicotinic receptor
Depolarizing works by excessive agonist stimulation
D-tubocurarine
Succinycholine

Question 2

How do we reverse non depolarizing neuromuscular blocking agents, 2 things?

Answer 2

Acetylcholine esterase blockers to raise the level of Ach

Anticholinergic agents co-administered to prevent adverse cholinergic effects at muscarinic receptors

Question 3

What is a big time adverse effect of d-tubocurarine?

Answer 3

Significant histamine release

Question 4

2 drug to drug interactions for non depolarizing neuromuscular blocking agents?

Answer 4

Anesthetics prolong the blocking effect

Aminoglycosides enhance the blocking effect as well.

Question 5

What two patient populations will have prolonged effects of taking non depolaring neuromuscular agents?

Answer 5

Old people with renal and liver impairment

M gravis patients

Question 6

What two patients are resistant to non depolarizing blocking agents?

Answer 6

Severe burns

Upper motor neuron disease

Question 7

What is a unique clinical pearl of cisatracurium?

Which non depolarizer has the most rapid time of onset?

Answer 7

Can be used even with significant renal and hepatic failure

Rocuronium

Question 8

What is phase 1 blocking of succinylcholine and what agents augment the blocking?

Answer 8

Stimulation of the nicotinic receptors ultimately leading to flaccid paralysis.
Cholinesterase blockers

Question 9

What is phase 2 blocking by succinylcholine and what agent reversing this blocking?

Answer 9

This is a desensitizing blocking but AchE blockers will reverse it

Question 10

Clinical application of succinylcholine?

Answer 10

Rapid induction

Question 11

3 adverse effects of succinylcholine?

Black Box Warning of succinylcholine?

Answer 11

Cardiac arrhythmias, hyperkalemia, post op pain, malignant hyperthermia, increased intraocular pressure.

Cardiac arrest! Rhabdomyolysis with hyperkalemia leading to ventricular arrhythmias, cardiac arrest and death.

Question 12

What is the big time drug to drug interaction of succinylcholine and how is it treated?

Answer 12

When given with Anesthetics, it can cause malignant hyperthermia which is treated by dantrolene.

Question 13

4 main uses of neuromuscular blocking agents?

Answer 13

Surgical relaxation, tracheal intubation, control of ventilation and treatment of convulsions.

Question 14

What are the three subgroups of ACHE blockers and what are the respective duration of action of each?

Answer 14

Alcohols have shortest
Carbamic acid esters are medium
Organophosphate have the longest and required pralidoxime to quickly regenerate ACHE.

Question 15

What are the 3 drugs that are the standard ACHE blockers to use in M gravis?

Answer 15

Pyridostigmine, neostigmine, and ambenonium

Don’t cross blood brain barrier

Question 16

How do we describe m gravis crisis vs. cholinergic crisis and how do we distinguish between the two?

Answer 16

M gravis crisis is severe muscle weakness from having m gravis that requires intubation
Cholinergic crisis is excessive ACHE blocking that is manifested by weakness
Give a ACHE blocker and if it gets better, M gravis. If it doesn’t, cholinergic crisis.

Question 17

What drug is commonly used to reverse neuromuscular blocking drug induced paralysis?

Answer 17

Neostigmine

Question 18

What two conditions to remember that are treated with ACHE blockers?

Answer 18

Glaucoma and dementia

Question 19

What effect will ACHE blockers have on the following scenarios?
Blockage from non depolarizing agents?
Blockage by succinylcholine?
Cholinergic agonists?
Beta blockers?

Answer 19

Diminish the blockage
Phase 1 they make it worse, phase 2 they reverse the block
Enhances effect of ACH
ACHE blockers can potentially enhance the bradycardic effects

Question 20

What is the triple therapy usually given to someone with organophosphate toxicity?

Answer 20

Atropine, pralidoxmine, and a benzodiazepine