Neuromuscular Blocking Agents Flashcards

1
Q

Motor nerves release ____ onto ____ receptors

A

neuromuscular nicotinic receptors mediate skeletal muscle contraction in response to acetylcholine

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2
Q

Somatic Nerves emanate from the ______ and innervate ______ with ___ synapses outside the CNS

A

Somatic Nerves emanate from the spinal cord and innervate skeletal muscle with no synapses outside the CNS

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3
Q

Somatic nerve signal terminated by:

A

Signal is terminated by degradation of Acetylcholine - by Acetylcholinesterases

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4
Q

Anticholinesterases are useful in treating ____________

A

Anticholinesterases are useful in treating Myasthenia gravis

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5
Q

___________ are useful in treating Myasthenia gravis

A

Anticholinesterases are useful in treating Myasthenia gravis

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6
Q

Acetylcholine + Acetylcholinesterase –>

A

Acetate + Choline

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7
Q

Acetylcholine at nicotinic receptor results in …. (pathway)

A

Na influx
Depolarization
muscle action potential
opening of voltage-sensitive Ca2+ channel
release of Ca2+ from sarcoplasmic reticulum
contraction

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8
Q

Nicotinic receptor historically blocked by

A

historically blocked by alpha-bungarotoxin from krait or cobra (Naja naja) venom (snake)

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9
Q

Agents prolonging Acetylcholine action (____, _____, _____) _______ muscle depolarization & contraction

A

Agents prolonging Acetylcholine action (Neostigmine, Pyridostigmine, Edrophonium) augment muscle depolarization & contraction- relevant to Myasthenia gravis

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10
Q

Agents blocking acetycholine release (_______) will prevent both _____ & _______

A

Agents blocking acetycholine release (Botulinum toxin) will prevent both muscle depolarization & contraction- relevant to cosmetics, muscle spasms

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11
Q

nicotinic receptor blockers (_____, ________) will prevent both ___________ & _________

A

nicotinic receptor blockers (d-tubocurarine, Mivacurium) will prevent both muscle depolarization & contraction- relevant to surgical paralysis

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12
Q

Something that blocks calcium-induced calcium release (________) will block ________ but not _______

A

Something that blocks calcium-induced calcium release (Dantrolene) will block contraction but not depolarization- relevant to Malignant Hyperthermia

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13
Q

Autoimmune disease resulting in destruction of nicotinic receptors on skeletal muscle

A

Myasthenia gravis

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14
Q

Treatment for myasthenia gravis

A

Treatment includes anticholinesterases (pyridostigmine, neostigmine)

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15
Q

Diagnosis for myasthenia gravis

A

Diagnosis can include the short acting anticholinesterase edrophonium (Tensilon test)

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16
Q

(Mestinon, Regonol) - used in myasthenia gravis or to reverse competitive neuromuscular antagonism; can be used prophylactically to prevent actions of nerve gases (tabun, soman)

A

Pyridostigmine

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17
Q

(Prostigmin)- used in myasthenia gravis but poorly absorbed from the gut; used more in hospitalized patients

A

Neostigmine

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18
Q

used to diagnose myasthenia gravis (vs. cholinergic crisis)

A

Edrophonium (Tensilon injectable)

increases strength in a myasthenic crisis and decreases strength in a cholinergic crisis (too much acetylcholine)

19
Q

principal behind a cholinergic crisis

A

nicotinic receptor - excessive stimulation of nicotinic receptors desensitizes organ to further stimulation

20
Q

Toxicity of anticholinesterases

A

SLUDGE (sweating, lacrimation, urination, diarrhea, GI distress, emesis)

21
Q

Used primarily in surgery to paralyze skeletal muscle

A

Neuromuscular blockers

22
Q

What do neuromuscular blockers block?

A

block nicotinic receptors on skeletal muscle

23
Q

Two types neuromuscular blockers?

A

Competitive, depolarizing

24
Q

Competitive blockers (eg)

A

d-tubocurarine, pancuronium, vecuronium, atracurium, metocurine, pipecuronium, mivacurium, rocuronium

25
Q

Depolarizing agents (Eg)

A

succinylcholine

26
Q

Mechanism of competitive blockers

A

competitive compete for nicotinic receptor sites - block Na+ influx, depolarization and contraction

27
Q

Succinylcholine mechanism

A

depolarizes end plate of muscle- chronic Na+ influx causes depolarization; fasciculations precede flaccid paralysis

28
Q

Anticholinesterases reverse block of ______

A

Competitive blockers

29
Q

Anticholinesterases may augment block of _________

A

Depolarizing blockers

30
Q

Fasciculations precede flaccid paralysis by ________

A

Depolarizing blockers

31
Q

___________ agents release K

A

Depolarizing agents

32
Q

Ether, halogenated anesthetics, streptomycin, tetracycline ________ competitive block

A

Ether, halogenated anesthetics, streptomycin, tetracycline enhance competitive block

33
Q

Anticholinesterases- _________ competitive blocker but __________ a depolarizing blocker

A

Anticholinesterases- antagonize competitive blocker but potentiate a depolarizing blocker

34
Q

epinephrine and norepinephrine - slight ability to reverse _____________

A

epinephrine and norepinephrine - slight ability to reverse competitive blockade

35
Q

Toxic effects of neuromuscular blockers

A

Apnea, histamine release, cardiovascular collapse

Malignant hyperthermia caused by halothane and succinylcholine

36
Q

Tx for malignant hyperthermia

A

treatment is dantrolene (dantrium) - inhibits Ca2+ release from sarcoplasmic reticulum by blocking the Ryanodine receptor (Calcium-induced calcium release)

37
Q

Uses for neuromuscular blockers

A

with anesthetics; prevention of seizures in electroshock therapy; nerve root pain vs muscle spasm impinging on nerve

38
Q

Absorption, metabolism of neuromuscular blockers

A

Absorption- Quaternary ammonium (i.v.); Metabolism - usually by kidneys except atracurium

39
Q

Depolarizing agents - avoid use in ____ patients, why

A

Avoid in burn patients (burned muscle increases the concentration of nicotinic receptors resulting in excessive potassium release in response to succinylcholine)

40
Q

Usually used for tracheal intubation to prevent aspiration of gastric contents; __________ is preferred for this because of its rapid action

A

succinylcholine

41
Q

Can produce malignant hyperthermia -treat with calcium antagonist, dantrolene

A

succinylcholine

42
Q

Succinylcholine has ______ duration of action

A

Short duration of action because of rapid metabolism (butyrylcholinesterase)

43
Q

Botulinum toxin mechanism

A

Prevents acetylcholine release by cleaving proteins (SNAP25) necessary for acetylcholine exocytosis