Pharmacology of Neuromuscular Blockers

Question 1

What does Ach hydrolyze into?

Answer 1

Acetate and choline

Question 2

What are the three skeletal muscle relaxants acting at the neuromuscular junction used in therapy?

Answer 2

Competitive Neuromuscular Blockers
Depolarizing Neuromuscular Blockers
Botulinum Toxin

Question 3

What are two types of competitive neuromuscular blockers?

Answer 3

Isoquinolones

Steroid-like

Question 4

What is a common direct acting muscle relaxant?

Answer 4

Dantrolene

Question 5

What is a common depolarizing neuromuscular blocker?

Answer 5

Succinylcholine

Question 6

What are common Isoquinolones?

Answer 6

Atracurium
Cisatracurium
Doxacurium

Question 7

What are common steroid-like skeletal muscle relaxants?

Answer 7

Pancuronium
Rocuronium
Vecuronium

Question 8

What are two general chemical types of competitive neuromuscular blockers?

Answer 8

Aliphatic chain bis-quaternaries

Steroid-like chain bis-quaternaries

Question 9

How do competitive neuromuscular blocking agents work?

Answer 9

Competitively inhibit acetylcholine from binding to the nicotinic receptor at the neuromuscular junction

Question 10

Why do isoquinolines and steroid-like drugs not work well on muscarinic receptors?

Answer 10

Because they have 2 positive charges and fit poorly into a ganglionic nicotinic receptor

Question 11

What happens when pancuromium or rocuronium are administered?

Answer 11

Pupil dilation

Tachycardia

Question 12

What gives cisatracurium an advantage over atracurium?

Answer 12

Atracurium caused release of histamine whereas cisatracurium does not so there is no inflammation

Question 13

How do non-depolarizing agents work?

Answer 13

Competitively inhibit acetylcholine binding to nicotinic receptors at the neuromuscular junction

Question 14

What drug reverses the neuromuscular blockade?

Answer 14

Neostigmine (anticholinesterase)

Question 15

How are steroid like NM blockers excreted?

Answer 15

In bile and renally

Question 16

What is the order of susceptibility to blockade?

Answer 16

Small muscles of eye -> Muscles of hand, facial muscles -> Diaphragm and vocal cords

Question 17

What is the byproduct of atracurium and cisatracurium hydrolysis?

Answer 17

Laudosine

Question 18

What happens when succinylcholine is administered?

Answer 18

Initially there is a repeated activation of nicotinic receptors (muscle rigidity) followed by flaccid paralysis (muscle is not sensitive to depolarization anymore)

Question 19

Succinylcholine initially stimulates autonomic ganglia causing what?

Answer 19

Bradycardia (prevented by atropine) and cardiac arrhythmia

Question 20

What can Succinylcholine cause?

Answer 20

Hyperkalemia: cardiac arrest/arrhythmia

Question 21

How does Dantrolene work?

Answer 21

Binds to ryanodine (RyR1) receptors in skeletal muscle not allowing calcium to be released from SR

Question 22

Why does Dantrolene not work in smooth or cardiac muscle?

Answer 22

They have RyR2 not RyR1

Question 23

What is Dantrolene used to treat?

Answer 23

malignant hyperthermia

Question 24

How many types are botox are approved for use?

Answer 24

2 type A

1 type B