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Pharmacology > Exam5- Local Anesthetics > Flashcards

Exam5- Local Anesthetics Flashcards

1
Q

local anesthetics vs analgesic drugs

A 
analgesic= specifically inhibit nociceptive pathway
local= non-secific inhibitors of neuronal conduction
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2
Q

afferent nociceptors

A

=Adelta and C fibers

-conduct thermal , intense mechanical, and chemical stimulation to a second order neuron or brain

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3
Q

Local Anesthetic Mechanism of Action

A

block voltage gated Na+ channels on nerve membranes

=stops generation and conduction of action potentials

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4
Q

locals will more readily reach their sites of action when they are in ___ form

A

LIPID SOLUBULE (UNCHARGED)

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5
Q

all locals are strong/weak acids/bases?

A

WEAK BASES

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6
Q

pH of all locals are between ___ and ____

A

7.5 and 9.5

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7
Q

physiological pH =

A

7.4

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8
Q

most of the drug will begin it its protonated/non protonated form

A

protonated
drug pH = 7.5 - 9.5
physiological pH = 7.4

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9
Q

pKa = pH at___

A

equilibrium of BH+ and B

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10
Q

when pH= 7.4 base is protonated/nonprotonated

A

BH+

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11
Q

when pH>pKa there is more ___

A

B

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12
Q

lidocaine has a pKa of

A

7.9

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13
Q

the closer pKa is to physiological pH the ____ the onset of the drug.

A

faster

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14
Q

fiber diameter/myelination affects___

A

susceptibility to local anesthetic

  • larger nerves are less susceptible to block than smaller nerves
  • myelinated nerves are less susceptible than non-myelinated n.
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15
Q

firing frequency and susceptibility to locals

A

locals bind active channels more readily than resting channel

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16
Q

position of fiber affects its susceptibility to locals….

A

superficial fibers are more easily reached ∴ more susceptible

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17
Q

pain and temperature neuron fiber type

A

delta

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18
Q

pain and temp neuron diameter

A

2-5um ∴ easy to target

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19
Q

order of nerve function loss:

A 
sympathetic
pain 
cold
warm 
touch 
motor
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20
Q

critical length hypothesis

A

in order to be effective the field of action of a local anesthetic must include at least 3 nodes of Ranvier

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21
Q

axon size and number of nodes ranvier

A

larger axons= less nodes
small axons= more nodes
∴smaller axons are more susceptible to locals bc there are more nodes within a given nerve block field

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22
Q

amide locals list

A 
lidocaine 
mepivacaine
prilocaine
bupivacaine
articaine
ropivacaine
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23
Q

ester locals list

A 
cocaine
procaine
tetracaine
benzocaine
proparacaine
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24
Q

amides or esters are metabolized in blood

A

esters
-readily hydorlyzed by esterases in blood into PABA
PABA= common allergy

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25
Q

amide metabolism

A

cytochrome p450 in liver
∴ have a longer duration of action than esters
-cause less allergic reactions than esters

26
Q

ester vs amide pKa

A

esters usually have a higher pKa

∴ slower onset and shorter duration

27
Q

amides with short duration of action

A

prilocaine and lidocaine

28
Q

amides with intermediate duration of action

A

mepivacaine

articaine

29
Q

amides with long duration of action

A

ropivacaine

30
Q

three routes of local administration

A
  1. topical
  2. infiltration/nerve block
  3. epidural/spinal
31
Q

____ are commonly used for topical applicaiton

A

binzocaine

tetracaine

32
Q

___ are commonly used for infiltration

A 
licocaine
mepivacaine
prilocaine 
articaine
bupivacaine
(all amides)
33
Q

all locals except cocaine are vaso____

A

dilators

34
Q

locals that are the least vasodilators

A

mepivacaine
prilocaine
∴ don’t need to be delivered with a vasoconstrictor

35
Q

vasoconstrictors benefits

A
  1. prolong the duration of anesthesia by preventing diffusion from the site of action
  2. limit systemic toxicity of local anesthetics
  3. reduce blood loss for surgical procedures
36
Q

epinephrine hydorcholide

A

most common with local injection

only targets alpha-1 receptors

37
Q

levonordefrin hydrochloride

A

less common

selective alpha-1 receptor agonists

38
Q

alpha-1 agonists should be used with caution w/___

A

patients with cardiovascular disease
because they cause hypertension
**ALWAYS avoid delivery into systemic circulation and only administer via infiltration when necessary at the lowest dose possible

39
Q

locals and MAO oxidase inhibitors

A

-can increase the effects potentially resulting in a hypertensive crisis

40
Q

lidocaine

A

=most commonly used local anesthetic

  • common prep= 2% lidocaine hydrochloride with 1:100,000 epinephrine
  • safe for kids
  • inexpensive
41
Q

articaine properties

A

similar to lidocaine

42
Q

bupivacaine properties

A

prolonge duration of action

43
Q

mepivacaine properties

A

very little vasodilation

doesn’t require a vasoconstrictor

44
Q

prilocaine properties

A

doesn’t require a vasoconstrictor

45
Q

benzocaind

A

=ester used in dentistry
-used topically as a numbing agent
(no longer via infiltration)

46
Q

one cartridge=___ ml

A

1.8ml

47
Q

2% =___ mg/ml

=___ mg/cartridge

A

20mg/ml

=36mg/cartridge

48
Q

1:10000 epi=___ ug/ml

=___ug/cartridge

A

10ug/ml

=18ug per cartridge

49
Q

EMLA

A

Eutectic mixture of local anesthetics
=2.5%prilocaine and 2.5% lidocaine
-for pain and itching

50
Q

LMX-4

A

=liposomal formulation of 4% lidocaine

-for pain and itching

51
Q

topical locals for pain and itching

A

EMLA
LMX-4
tetracaine
benzocaine

52
Q

ophthalmology locals

A

proparacaine
-for ocular proceudres
repeated administration=corneal damage/blindness

53
Q

locals for minor lacerations

A

=topical analgesics with epinephrine
TAC= tetracaine, adrenalin/epi, cocaine
LET= lidocaine, epinephrine, tetracaine

54
Q

locals for surgical wounds

A

pre-surgical infilatration

55
Q

locals for major lacerations

A

pack with agents soaked with TAC or LET

56
Q

digital injury locals

A

DO NOT USES EPINEPHRINE you can use digits form ischemia!!!!

57
Q

induced nerve block

A

administered into space around spinal column, below L1

  1. epidural space = epidural block
  2. subarachnoid space =spinal block
  3. paravertebral region= paravertebral block (more diffuse)
58
Q

epidural anesthesia

A
  • between L3 and L4 through ligament flavor
  • most commonly ropivacaine
  • bupivacaine is also used but is more cardiotoxic (arrhythmias)
59
Q

systemic toxicity of local anesthetic

A

CNS: excitation initially then severe toxicity = seizures
Cardiovascular: decreased conduction, arrhythmias
hypotension, reduced autonomic activity
Hemoblobin: prilocaine is metabolized in the liver and then converts hemoglobin to methemoglobin

60
Q

PABA

A

paraaminobenzoic acid

=metabolite of ESTER anesthetics

Pharmacology (11 decks)

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