Neuromuscular Blockers Flashcards

1
Q

what are the only clinically useful nicotinic antagonists

A

skeletal muscle type nAChR’s (Nm)

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2
Q

what is the structure of all neuromuscular blocking drugs

A

analogues of acetylcholine

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3
Q

neuromuscular blockers are given by what route

A

IV

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4
Q

what is the difference between a non-depolarizing and a depolarizing block

A

non-depolarizing: nAChR antagonists
depolarizing: nAChR agonists

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5
Q

what are 2 considerations of neuromuscular blockers

A

animals fully conscious and no analgesia

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6
Q

in veterinary medicine, __________ is one of the most commonly used non-depolarizing neuromuscular blockers

A

atracurium

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7
Q

is atracurium a depolarizing or non-depolarizing neuromuscular blocker

A

non-depolarizing

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8
Q

what is the most common clinical use of atracurium

A

prevent eye movement during ocular surgery

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9
Q

what is a benefit of using atracurium during eye surgery

A

you can achieve complete muscle relaxation without the need for higher anesthetic doses, making it safer and a faster recovery

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10
Q

how does atracurium cause muscle relaxation

A

it competitively blocks AChRs at the NMJ

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11
Q

what are the pharmacokinetic considerations of atracurium

A

1) must be injected IV because it is highly polar (ionized)
2) duration of effect varies with dosage
3) usual recovery time (20min-30 min, sometimes 1h) follows last dose

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12
Q

what drugs can you use to reverse the effects of atracurium

A

neostigmine, pyridostigmine, edrophonium

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13
Q

what is a major consideration of using neuromuscular blockers that limits their use to in referral practices by board-certified veterinarians

A

can get dose-dependent respiratory paralysis

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14
Q

what is the order of paralysis of muscles when using neuromuscular blockers

A

1) extraocular
2) neck/face/hands/feet
3) abdomen/arms/legs
4) eye blink
5) respiratory and diaphragm

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15
Q

what is the order of recovery of muscles when using neuromuscular blockers

A

1) respiratory and diaphragm
2) eye blink
3) arms/legs/abdomen
4) face/neck/hands/feet
5) extraocular

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16
Q

what is the main depolarizing neuromuscular blocker

A

succinylcholine

17
Q

how does succinylcholine cause paralysis

A

acts like a nicotinic agonist -> initial depolarization causes muscle contractions, then cannot repolarize so Na channels remain inactivated -> flaccid paralysis -> rapidly degraded by ACh esterase

18
Q

what is the main clinical use of succinylcholine today

A

to help horses go down smoothly prior to euthanasia

19
Q

what is the onset and duration of action of atracurium

A

3min; approx 45 min (dose-dependent)

20
Q

what is the onset and duration of action of succinyl choline

A

less than 1 min; 90s

21
Q

what is the role of muscle relaxants

A

decrease muscle tone/spasms without completely inhibiting voluntary contractions -> useful to alleviate muscle spasms associated with certain clinical conditions (IVDD, blocked cat…)

22
Q

what are the 2 forms of muscle relaxants

A

centrally acting and peripherally acting

23
Q

what are the 3 classes of centrally acting muscle relaxants

A

1) benzodiazepines (ex. Valium)
2) methocarbamol
3) guaifenesin

24
Q

what is the peripherally acting muscle relaxant

A

dantrolene

25
how do benzodiazepines cause muscle relaxation
facilitate GABA activity in the CNS
26
what are 2 considerations of benzodiazepines
1) metabolism can be altered by other drugs 2) may cause CNS depression
27
what are the 3 main issues with methocarbamol
mechanism unknown, efficacy uncertain, contraindicated in renal diseases
28
what is the mechanism of action of guaifenesin
inhibits interneurons in motor reflexes
29
how is guaifenesin used
given IV with injectable anesthetics for induction
30
how does dantrolene work
inhibits Ca release from the SR