Exam 2 - Drugs Targeting the Neuromuscular Junction

Question 1

What is a synapse? (structure and function)

Answer 1

• the structure formed between a motor neuron and muscular fiber
• transmit nerve impulses between neurons or a neuron and a target cell

Question 2

How does myasthenia gravis disrupt the signaling at NMJ?

Answer 2

the production of antibodies attach acetylcholine receptors on muscle cell surfaces
* blocks the binding of acetylcholine

Question 3

How can myasthenia gravis be treated?

Answer 3

AChE inhibitors (neostigmine) effectivelt increase ACh concentration at the NMJ, causing more Nm channels to open = more muscle contraction

Question 4

What do neuromuscular blocking agents do?

Answer 4

inhibit Nm = suppressing muscle contraction

Question 5

What are the therapeutic uses of neuromuscular blocking agents?

Answer 5

• muscle relaxation
• tracheal intubation
• reduce convulsions

Question 6

What are 2 important things to consider when using neuromuscular blocking agents?

Answer 6

• respiration
• cardiovascular function

Question 7

What is important to remember about molecules with quarternary N groups?

Answer 7

poor lipid solubility and inability to cross BBB

Question 8

Describe nondepolarizing neuromuscular blocking agents.

Answer 8

competitive antagonist, prevents depolarization = reducing muscle contractions

Question 9

What is the mechanism of action for nondepolarizing neuromuscular blocking agents?

Answer 9

blocking agents bind to Nm receptor but do not activate/depolarize the cell = prevention of muscle contraction

Question 10

What are examples of nondepolarizing neuromuscular blocking agents?

Answer 10

• D-tubocurarine
• pancuronium
• cistracurium
• veceronium

Question 11

Can an AChE (neostigmine) reverse the effects of nondepolarizing neuromuscular blocking drugs?

Answer 11

• yes
• neostigmine elevates ACh allowing it to compete nondepolarizing agent off

Question 12

What are contraindications of nondepolarizing neuromuscular blocking drugs?

Answer 12

• use w/ antibiotics (increase NMJ block)
• myasthenia gravis

Question 13

Describe depolarizing neuromuscular blocking agents.

Answer 13

initially noncompetitive agonist (depolarization) then causes persistent inhibition = reducing muscle contraction

Question 14

What is the mechanism of action for depolarizing neuromuscular blocking drugs?

Answer 14

Phase 1
* depolarize membrane so it cannot respond to later impulses

Phase 2
* membrane repolarizes but it resistant to depolarization (desensitization)

Question 15

What is an example of depolarizing neuromuscular blocking drugs?

Answer 15

succinylcholine

Question 16

Can an AChE inhibitor (neostigmine) reverse the effects of depolarizing neuromuscular blocking drugs?

Answer 16

no

Question 17

What are the contraindications of depolarizing neuromuscular blocking agents?

Answer 17

organophosphate poisoning