Local Anesthetic Pharm (EB) Flashcards

1
Q

Local anesthetic amides (5)

A

lidocaine Bupivacaine Ropivacaine Mepivacaine Prilocaine

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2
Q

Local anesthetic esters (4)

A

cocaine Procaine Tetracaine Amethocaine

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3
Q

Myelin layer of B nerve fibers? Function? Order of block? Effect?

A

Myelin layer = light Function = autonomic, preganglionic, sympathetic Order of block = 1 Effect = warmth (vasodilation)

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4
Q

Myelin layer of C nerve fibers? Function? Order of block? Effect? ?

A

Myelin layer = none Function = pain Order of block =2 Effect = loss of pain sensation

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5
Q

Myelin layer of Adelta nerve fibers? Function? Order of block? Effect? ?

A

Myelin layer = light Function = pain, temp Order of block = 2 Effect = loss of pain and temp sensation

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6
Q

Myelin layer of Agamma nerve fibers? Function? Order of block? Effect? ?

A

Myelin layer = moderate Function = muscle tone Order of block = 3 Effect = loss of proprioception

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7
Q

Myelin layer of Abeta nerve fibers? Function? Order of block? Effect? ?

A

Myelin layer = moderate Function = touch, pressure Order of block = 4 Effect = loss?

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8
Q

Myelin layer of Aalpha nerve fibers? Function? Order of block? Effect? ?

A

Myelin layer = heavy Function = motor Order of block = 5 Effect = paralysis

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9
Q

How does frequency of stimulation influence the onset of blockade?

A

traumatized tissue more sensitive to local anes blockade

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10
Q

Order of regional local anes blocking?

A

proximal regions are blocked sooner than distal regions

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11
Q

Which kind of fibers are blocked first (conventionally)

A

small sensory fibers are blocked before larger sensory and motor fibers

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12
Q

potency of a local anes is closely correlated to

A

lipid solubility

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13
Q

What are nerve membranes made out of to help with the potency of local anes?

A

lipids

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14
Q

What influences the speed of onset of a local anes?

A

pKa

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15
Q

PKa of local anes

A

weak bases = 7.6 - 9.1

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16
Q

At tissue pH of 7.4, < 50% of local anesthetics are

A

nonionized

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17
Q

What form of local anesthetics diffuses across the cell membrane

A

non-ionized

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18
Q

pH _ in infected tissues?

A

decreases

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19
Q

Because pH decreases in infected tissues, what happens to the non-ionized fraction of local anes? What happens to the action of localed anes?

A

reduced non-ionized fraction. Reduced or absent local anes action

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20
Q

Protein binding and duration of action of bupivacaine?

A

95% protein bound, Long duration

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21
Q

Protein binding and duration of action of lidocaine

A

65% protein bound, Short duration

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22
Q

Effect of action of local anes on vessels? What effect does this have on the drug?

A

vasodilation&raquo_space; fastens uptake of drug, shortens duration of effect

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23
Q

Additives to a local anesthetic (3)

A

vasoconstrictors (epinephrine) Hyaluronidase Bicarbonate

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24
Q

Why is epinephrine added to a local anesthetic?

A

delayed absorption, prolonged action

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25
Q

Con of adding epinephrine to a local anesthetic?

A

localized ischemia possible

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26
Q

Why is hyaluronidase added to a local anesthetic?

A

increasing tissue permeability Facilitates diffusion Rapid onset

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27
Q

Why is bicarbonate added to a local anesthetic?

A

buffers G+ Faster diffusion Shortens onset and duration Injection less painful

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28
Q

What metabolized local anes esters into inactive compounds?

A

plasma cholinesterases

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29
Q

NB to a long IV infusion of amide local anes?

A

slowly metabolized by the liver so can accumulate after long IV infusion

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30
Q

Pros of loco-regional use of local anesthetics (3)

A

easy to use Effective and reliable analgesia Minimal systemic effects

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31
Q

CV effects of loco-regional use of local anesthetic

A

decreased CV responses to surgical stimulation

32
Q

Effect of loco-regional use of a local anesthetic on the MAC

A

decreases

33
Q

How are local anesthestics systemically given?

A

lidocaine CRI

34
Q

How can lidocaine reduce hyperalgesia?

A

central analgesic effect when given CRI

35
Q

Effect of lidocaine CRI on MAC

A

MAC sparing effect

36
Q

Effect of lidocaine CRI on GI tract in horses?

A

prokinetic activity

37
Q

CV effect of lidocaine CRI

A

anti-arrythmic properties

38
Q

Effect of lidocaine CRI on inflammation

A

anti-oxidant and inflammatory modulator activity

39
Q

CNS effects of local anes

A

initial CNS tox&raquo_space; Sedation, disorientation, ataxia Muscle tremor, convulsions, respiratory depression

40
Q

CV effects of local anesthestics

A

CV toxicity» Depress myocardial contractility Profound hypotension Arrhythmias CV collapse

41
Q

What local anesthetics cause methamglobinemia?

A

prilocaine Benzocaine

42
Q

Why should you not give 5% lidocaine

A

causes an irreversible block within minutes

43
Q

Problems of high concentrations of local anesthetics?

A

tissue irritation Neurotoxicity

44
Q

Problem with given epinephrine

A

tissue ischemia

45
Q

Problem with given ester local anesthetics

A

allergic rxns

46
Q

How do you avoid toxicity with local anesthetics (4)

A

know the toxic doses Weigh the pt calculate dose avoid unintentional IV inj

47
Q

The toxicity of local anesthetics is _

A

additive

48
Q

How do you tx seizures causes by local anes

A

benzos Propofol CRI

49
Q

How do you tx CNS depression caused by local anes

A

supportive care Mechanical ventilation

50
Q

How do you tx cardiac problems caused by local anes

A

supportive care Fluids O1 Atropine Antiarrythmic

51
Q

How does lipid rescue work to tx local anes systemic tox?

A

remove lipophilic toxins from affected tissue Surrounds local anesthetic molecules in plasma

52
Q

Onset of lidocaine

A

rapid (5 min)

53
Q

duration of lidocaine

A

short (1-2 hrs)

54
Q

uses of lidocaine

A

nerve block Epidural/spinal Infiltration CRI(IV)

55
Q

What cardiac thing can lidocaine be used to tx?

A

ventricular tachycardia Arrhythmias

56
Q

What animal is more sensitive to the toxic effects of lidocaine?

A

cats

57
Q

What is the side effect of using lidocaine as a spray in order to ET tube a car?

A

laryngeal edema (due to additives)

58
Q

duration and onset of mepivicaine?

A

rapid onset (5 minutes), Short duration (1-2 hrs)

59
Q

routes of administration of mepivicaine

A

SC Local infiltraton Intra-articular

60
Q

Why is mepivicaine preferred for equine nerve blocks?

A

less irritant than lidocaine

61
Q

What major use does mepivicaine have over lidocaine?

A

can be used for intra-synovial analgesia

62
Q

Onset of bupivacaine

A

slow (20-30 minutes)

63
Q

Duration of bupivacaine

A

long duration (4-6 hours)

64
Q

What drug has a higher cardiotoxicity than lidocaine?

A

bupivacaine

65
Q

Uses of bupivacaine

A

nerve block Epidural/spinal

66
Q

Which isomer of bupivacaine is less tocic?

A

L-bupivacaine

67
Q

What drug damages articular cartilage?

A

bupivacaine

68
Q

What entantiomer of ropivacaine is available?

A

S

69
Q

Is ropivicaine more or less soluble than ropivacaine?

A

less

70
Q

What LA: has a faster return to motor function? Why?

A

ropivacaine Less impact on muscle fibers

71
Q

What is EMLA cream?

A

eutectic mixture of local anesthetics 2.5% lidocaine and 2.5% prilocaine

72
Q

What is the main use of EMLA cream?

A

skin anesthesia prior to IV catheter

73
Q

Onset of action of EMLA cream?

A

20-30 minutes

74
Q

Why use opioids with a local anesthetic?

A

increase efficacy and extend duration of block

75
Q

What blocks is morphine used in?

A

intra-articular and epidural blocks

76
Q

Which a2 agonists may extend the duration and increase efficacy of local blocks?

A

medetomidine Dexmedetomidine

77
Q

Why is ketamine use with LA?

A

epidural anesthesia