local anesthetic Flashcards

1
Q

List the local anesthetic: Esters

A
  • Procaine (Novocain®)
  • Tetracaine (Pontocaine®)
  • Benzocaine (Americaine®)
  • Cocaine
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2
Q

what drug class is Lidocaine (Xylocaine®) in

A

local anesthetics: amides

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3
Q

what drug class is Prilocaine (Citanest®) in

A

local anesthetics: amides

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4
Q

what drug class is Bupivacaine (Marcaine®) in

A

local anesthetics: amides

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5
Q

what drug class is Mepivacaine (Carbocaine®) in

A

local anesthetics: amides

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6
Q

what drug class is Ropivacaine (Naropin®) in

A

local anesthetics: amides

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7
Q

what drug class is Etidocaine (Duranest®) in

A

local anesthetics: amides

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8
Q

what drug class is Articaine (Septocaine®) in

A

local anesthetics: amides

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9
Q

what drug class is Dibucaine (Nupercainal®) in

A

local anesthetics: amides

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10
Q

what drug class is Baclofen (Lioresal®) in

A
  • GABA-mimetic
  • muscle relaxant
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11
Q

what drug class is Diazepam (Valium®) in

A
  • Benzodiazepine
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12
Q

list the 4 spinal cord or brain stem sedatives

A
  • Cyclobenzaprine (Flexeril®)
  • Carisoprodol (Soma®)
  • Metaxalone (Skelaxin®)
  • Methocarbamol (Robaxin®)
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13
Q

local anesthetics are broken down into what 2 groups

A
  • esters
  • amides
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14
Q

do esters or amides have shorter duration of action? which has increased systemic toxicity?

A
  • Esters have shorter duration of action
  • Esters have increased systemic toxicity
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15
Q

local anesthetics are acids or bases?

A
  • weak bases
    • pKa = 7.5-9
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16
Q

What form does the local anesthetic need to be in to cross the cell membrane? what form binds to Na+ channel

A
  • non-ionized (LA + H+)
  • ionized (LAH+)
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17
Q

the closer the pKa is the physiological pH (7.4) the higher the concentration of the local anesthetic in what form? what benefit does this have

A
  • non-ionized form
    • membrane transport increases -> faster onset of action
      • ex: lidocaine (pKa 7.8) has a faster onset than bupivacaine (pKa 8.1)
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18
Q

what local anesthetic drug is an exception to the rule and even at a pKa of 3.5 is always in the non-ionized form ? route of administration?

A

Benzocaine

  • topical application only
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19
Q

how does bicarbonate affect LA transport across cell membrane

A
  • makes pH more basic and may increase non-ionized drug concentrations and thus, the degree of LA transport
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20
Q

MOA of local anesthestics

A
  • block Na+ channels and inhibit neuronal firing and the propagation of action potentials
    • When progressively increasing concentrations of a local anesthetic are applied to a nerve fiber, the threshold for excitation increases, impulse conduction slows, the rate of rise of the action potential declines, and finally, the ability to generate an action potential is completely abolished.
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21
Q

LA have high affinity for Na channels in what state

A
  • high affinity for channels in the activated (open state) and inactivated state and lower affinity for channels in the resting (closed) state
  • drug is more marked in rapidly firing axons than in resting fibers.
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22
Q

what effect does elevated calcium have of the MOA of local anesthetics

A
  • increase membrane potential; more channels are in resting state and the effect of LAs is diminished.
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23
Q

what effect does elevated potassium have of the MOA of local anesthetics

A
  • depolarize the membrane; more channels in inactivated state and the effect is enhanced
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24
Q

duration of action of local anesthetics is dependent on

A

spent at the site of action

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25
Q

List local anesthetics with a short duration of action

A
  • Procaine
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26
Q

List local anesthetics with a medium duration of action

A
  • cocaine
  • Mepivacaine
  • Lidocaine
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27
Q

List local anesthetics with a long duration of action

A
  • Tetracaine
  • Bupivicaine
  • Ropivicaine
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28
Q

toxic effects of LA are dependent on

A

half-life

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29
Q

how does epinephrine affect absorption of local anesthetic

A
  • epinephrine -> vasoconstriction
    • decreases diffusion of drug
    • prolongs duration of action
    • decreases systemic absorption and decreases risk of systemic toxicity
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30
Q

Where are Amides LA metabolized

A
  • Liver by CYP450
    • toxicity is more likely in pts with hepatic disease or reduced hepatic blood flow
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31
Q

Where are esters LA metabolized

A
  • rapidly metabolized by butyrylcholinesterases in the plasma
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32
Q

What is the problem with using local anesthetics for a differential block (trying to block pain)

A
  • block is not limited to intended site
  • also blocks motor nerves -> motor paralysis, respiratory impairment, hypotension
  • different degrees of sensory and motor nerve block in LA
    • bupivacaine little action on motor
    • etidocaine primarily affects motor
33
Q

what is the order of sensitivity to LA

A
  • sympathetic (blocked first) > sensory (pain) > touch > motor
34
Q

how does the intrinsic susceptibility of nerve fibers affect how they are blocked

A
  • 3 factors: diameter, degree of myelination, and conduction velocity
    • smaller fibers are blocked first and more sensitive
    • myelinated fibers are blocked faster than unmyelinated but less sensitive
    • the faster the conduction velocity, the slower the block
35
Q

cardiovascular side effects of local anesthetics

A
  • arrhythmias
  • vasodilation
  • hypotension
36
Q

which local anesthetic has the most cardiac side effects

A

Bupivacaine

37
Q

CNS effects of local anesthetics

A

depression of cortical inhibitory pathways

  • sedation
  • visual/auditory disturbances
  • muscle twitching
  • convulsions
38
Q

which type of local anesthetic is more prone to cause allergic reactions

A
  • Esters
39
Q

Procaine is an ester or amide? long or short duration of action

A
  • ester
  • short
40
Q

metabolic product of Procaine

A
  • para-aminobenzoic acid (PABA)
    • can cause allergic reactions
41
Q

Use of procaine

A
  • infiltration anesthesia
42
Q

Tetracaine is an ester or amide? duration of action?

A
  • ester
  • long duration of actions
43
Q

compare tetracaine and procaine in terms of toxicity

A

tetracaine 16 x more potent and more toxic

44
Q

use of tetracaine

A
  • ophthalmological use
  • spinal anesthesia
45
Q

Benzocaine is an ester or amide? route of adminstration?

A
  • ester
  • topical only
46
Q

adverse effects of Benzocaine

A

methemoglobinemia

47
Q

cocaine is an ester or amide

A
  • ester
    • used topically
48
Q

Lidocaine is an ester or amide

A
  • amide
49
Q

Use of Lidocaine

A
  • infiltration blocks
  • epidural anesthesia
50
Q

why is Lidocaine not preferred for spinal blocks

A
  • increased risk for Transient neurological symptoms (TNS)
51
Q

Prilocaine is ester or amide

A
  • amide
52
Q

compare the clearance of Prilocaine to the other amides

A

Prilocaine has the highest rate of clearance of the amides

53
Q

adverse effect of Prilocaine

A
  • methemoglobinemia
    • due to metabolites
54
Q

use of Prilocaine

A
  • largely limited to use in dentistry
55
Q

Bupivacaine is an ester or amide? duration of action

A
  • amide
  • long duraction of action
56
Q

adverse effects of Bupivacaine

A
  • cardiotoxicity
57
Q

Bupivacaine has a higher sensitivity to motor block or sensory block

A
  • more potent sensory block than motor block
58
Q

use of Bupivacaine

A
  • epidural during labor and childbirth
59
Q

MOA of Ropivacaine

A
  • amide
  • long acting
  • the S enantiomer of bupivacaine
  • less lipid soluble and cleared more rapidly than bupivacaine
    • less cardiac toxicity
60
Q

use of Ropivacaine

A
  • peripheral and epidural block
  • vasoconstricting effects at clinical doses
    • don’t need to add epinephrine
61
Q

Is Mepivacaine an ester or amide

A

amide

62
Q

Is Etidocaine an ester or amide

A

amide

63
Q

Does Etidocaine have more blocking effect on motor or sensory

A
  • inverse differential block
    • may cause motor block before or without sensory block
64
Q

Is Articaine an ester or amide

A
  • amide
  • also has an additional ester group
65
Q

use of Articaine

A

dental medicine

66
Q

Is Dibucaine an ester or amide

A
  • amide
    • topical use
67
Q

What is the Dibucaine number test

A
  • The dibucaine number is a measure of activity of butyrylcholinesterase (dibucaine inhibits wildtype)
    • Used to differentiate individuals who have mutations and deficiencies.
      • number of 80 or below is considered deficient
68
Q

MOA of Diazepam?

A

acts on GABAA receptor to facilitate GABA-mediated presynaptic inhibition in the spinal cord

69
Q

dose of Diazepam in use as muscle relaxant produces what side effect

A

heavy sedation

70
Q

MOA of Baclofen

A
  • agonist at GABAB receptors
  • opens K+ channels -> hyperpolarizaiton
  • inhibits Ca2+ influx -> decreases transmitter release
71
Q

MOA of Tizanidine

A
  • alpha 2 receptor agonist
    • produces both pre and post synaptic inhibition of spinal cord synaptic activity to decrease muscle spasticity
  • inhibits pain transmission in dorsal horn
72
Q

side effect of Tizanidine

A

sedation

73
Q

MOA of Dantrolene

A
  • inhibits ca2+ release from sarcoplasmic reticulum
  • interferes with excitation-contraction coupling of actin and myosin in skeletal muscle fiber
74
Q

Use of dantrolene

A
  • tx
    • neuroleptic malignant syndrome
    • malignant hyperthermia
75
Q

MOA of Botulinum toxin

A
  • inhibits ACh release from berve at NMJ
76
Q

use of Botulinum toxin

A
  • used locally to control muscle spasms following stroke or neurological injury
77
Q

List the drugs for acute local muscle spasms

A
  • Cyclobenzaprine (flexeril)
  • Carisoprodol (soma)
  • Metaxolone
  • Methocarbamol
78
Q

main side effect of drugs for acute local muscle spasms

A
  • significant sedation