[PF] LOCAL ANESTHETICS Flashcards

1
Q

_________ provide anesthesia & analgesia by blocking the transmission of pain sensation along nerve fibers

A

Local anesthetics

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2
Q

The key target of local anesthetics is the _________. The binding is _________ and is mediated by hydrophobic interactions.

A

voltage-gated sodium channel

intracellular

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3
Q

The degree of nerve blockade depends on both _________ and _________.

A

drug concentration and volume

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4
Q

Efficacy for clinical use of local anesthetics may be increased by addition of:

A
  1. epinephrine
  2. opioids
  3. ⍺2-adrenergic agonists
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5
Q

The rate of local anesthetic system absorption depends on:

A
  1. the site of injection
  2. the dose
  3. the drug’s intrinsic pharmacokinetic properties
  4. the addition of vasoactive agent
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6
Q

Cocaine is also known as:

A

Coca shrub (Erythroxylon coca)

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7
Q

First isolated in 1860, numbing of tongue

A

Albert Niemann

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8
Q

Cocaine’s physiological actions

A

Sigmund Freud

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9
Q

Topical anesthetic for ophthalmological surgery 1884

A

Carl Koller

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10
Q

Infiltration and conduction block anesthesia

A

Halstead

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11
Q

Amides

A
  • BUPIVACAINE
  • LEVOBUPIVACAINE
  • ETIDOCAINE
  • LIDOCAINE
  • MEPIVACAINE
  • PRILOCAINE
  • ROPIVACAINE
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12
Q

Esters

A
  • BENZOCAINE
  • CHLOROPROCAINE
  • COCAINE
  • PROCAINE
  • TETRACAINE
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13
Q

Block conduction by _______ or ________ permeability to Na+

A

decreasing or preventing

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14
Q

No propagation of ________ = nerve conduction fails

A

action potential

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15
Q

The degree of block depends on how the nerve has been _______ and on its __________.

A

stimulated

resting membrane potential

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16
Q

_________ frequency of stimulation and _______ membrane potential cause a greater degree of anesthetic block

A

Higher

More positive

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17
Q

Local anesthetic gains access to its binding site within the pore only when the Na+ channel is in an _________.

A

open state

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18
Q

Pain

A

Unmyelinated C fibers

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19
Q

Temperature

A

Myelinated Aδ fibers

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20
Q

Touch

A

Myelinated A (gamma) fibers

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21
Q

Deep pressure

A

Myelinated Aβ fibers

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22
Q

Motor function

A

Myelinated A (alpha) fibers

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23
Q

Epinephrine is a?

A

Vasoconstrictor

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24
Q

Epinephrine acts by _________ the rate of absorption, it localizes the anesthetic at the desired site.

A

decreasing

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25
Q

It allows the rate at which it is destroyed in the body to keep pace with the rate at which it is absorbed into the circulation.

A

Epinephrine

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26
Q

Reduces systemic toxicity

A

Epinephrine

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27
Q

Sympathomimetic amines: =

A

↑ O2 consumption of tissue + vasoconstriction

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28
Q

Sympathomimetic amines: ↑ O2 consumption of tissue + vasoconstriction =

A

hypoxia, local tissue damage

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29
Q

Regions with limited collateral circulation could produce:

A

irreversible hypoxic damage, tissue necrosis, gangrene

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30
Q

Central nervous system:

A
  1. Restlessness
  2. Tremor
  3. Clonic convulsion
  4. Depression
  5. Death
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31
Q

The myocardium ________ in electrical excitability, conduction rate, & force of contraction

A

decreases

*seen only after high systemic concentrations are attained & effects on the CNS are produced

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32
Q

Bupivacaine side effects:

A

Ventricular tachycardia & fibrillation

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33
Q

Inadvertent IV administration

A

Bupivacaine

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34
Q

Undesired effects in GIT

A

depress contractions in the intestines

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35
Q

Undesired effects in vascular and bronchial smooth muscles

A

relaxation

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36
Q

Undesired effects in sympathetic nervous system

A

paralysis

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37
Q

Undesired effects in uterine muscle

A

Increase resting tone

Decrease contraction

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38
Q

Undesired effects in intrapartum:

A

uterine contractions not depressed

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39
Q

Local anesthetics block ________.

A

nicotinic Ach receptors

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40
Q

Hypersensitivity manifest as:

A

allergic dermatitis or a typical asthmatic attack

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41
Q

Esters are hydrolyzed as:

A

Plasma cholinesterase

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42
Q

Esters

A
  1. Benzocaine
  2. Chloroprocaine
  3. Cocaine
  4. Procain
  5. Tetracaine
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43
Q

Amides:

A
  1. Lidocaine
  2. Prilocaine
  3. Bupivacaine
  4. Ropivacaine
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44
Q

Initially hydrolysis forming o-toluidine metabolite – Methemoglobinemia

A

Prilocaine

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45
Q

Hepatic cyps

A

N-dealkylation then hydrolysis

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46
Q

Amides are extensively bound to ___________.

A

⍺1-acid glycoprotein

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47
Q

↑ ⍺1-acid glycoprotein:

A
  1. cancer
  2. surgery
  3. trauma
  4. MI
  5. smoking
  6. uremia
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48
Q

↓ ⍺1-acid glycoprotein:

A

oral contraceptives

49
Q

Amides effect on neonate:

A

deficient in plasma proteins

*susceptible to toxicity

50
Q

Reduced cardiac output

A

Amides

*slows delivery of the amide compounds to the liver, reducing their metabolism and prolonging their plasma half-lives

51
Q

Toxicity and potential for abuse (decreased clinical use)

A

Cocaine

52
Q

Cocaine inhibit ________.

A

Catecholamine uptake (NE)

53
Q

Inhibition of catecholamine uptake leads to:

A
  1. sensitization to catecholamines
  2. vasoconstriction
  3. mydriasis
54
Q

inhibit DA uptake

A

euphoria

55
Q

used primarily for topical anesthesia of the upper respiratory tract

A

Cocaine

56
Q

Relief of pain for postherpetic neuralgia

A

Licocaine transdermal patch

57
Q

dental procedures

A

Oral patch transdermal patch

58
Q

(EMLA)

A

Lidocaine + Prilocaine

59
Q

topical analgesics

A

Lidocaine + Tetracaine

60
Q

More cardiotoxic

A

Bupivacaine

61
Q

It block cardiac Na+ channels during systole but dissociates much more slowly during diastole

A

Bupivacaine

62
Q

Cardiac toxicity by the Bupivacaine is difficult to treat and enhanced by coexisting:

A

acidosis, hypercarbia & hypoxemia

63
Q

amide + ester

A

Articaine

64
Q

For dental & periodontal procedures

A

Articaine

65
Q

Articaine rapid onset

A

(1-6 mins)

66
Q

Articaine duration of action

A

1 hour

67
Q

Rapid onset and short duration of action

A

Chloroprocaine

68
Q

Reduced acute toxicity due to its rapid metabolism

A

Chloroprocaine

69
Q

↑ incidence of back pain – tetany of paraspinus muscle – Ca2+ binding by EDTA

A

Chloroprocaine

70
Q

amide

A

Mepivacaine

71
Q

more toxic to neonate

A

Mepivacaine

72
Q

not used in obstetrical anesthesia

A

Mepivacaine

73
Q

ion trapping

A

Mepivacaine

74
Q

lower pH of neonatal blood

A

Mepivacaine

75
Q

Prilocaine can cause methemoglobinemia at a dose of ________.

A

8 mg/kg

76
Q

metabolism of the aromatic ring to o-toluidine

A

Prilocaine

77
Q

Less toxic than Bupivacaine

A

Ropivacaine

78
Q

First synthetic local anesthetic

A

Procaine

79
Q

Hydrolyzed in vivo to produce para-aminobenzoic acid which inhibits the action of sulfonamides

A

Procaine

80
Q

Long duration

A

Tetracaine

81
Q

Effective in the symptomatic relief of anal and genital pruritus, poison ivy rashes, and numerous other acute & chronic dermatoses

A

DIBUCAINE
DYCLONINE HYDROCHLORIDE
PRAMOXINE HYDROCHLORIDE

82
Q

Applied directly to wounds and ulcerated surfaces, where they remain localized for long periods of time, producing a sustained anesthetic action

A

Anesthetics of low solubility (Benzocaine)

83
Q

Can cause methemoglobinemia

A

Benzocaine

84
Q

1st LA used in ophthalmology

A

Cocaine

85
Q

Disadvantage of cocaine:

A

mydriasis, corneal sloughing

86
Q

used in patients sensitive to esters

A

Proparacaine

87
Q

Long-term administration is associated with retarded healing, pitting, and sloughing of the corneal epithelium, & predisposition of the eye to inadvertent injury

A

Tetracaine

88
Q

Block Na+ channel – no action potential

A

Biological toxins

89
Q

Channels in cardiac myocytes & dorsal root ganglion neurons are resistant

A

Biological toxins

90
Q

Paralysis of the respiratory muscles

A

Biological toxins

91
Q

Puffer fish (Fugu), newts of Salamandridae, Costa Rican frog Atelopus

A

Tetrodotoxin

92
Q

clams & shellfish – red tide

A

Saxitoxin

93
Q

If the patient survives paralytic shellfish poisoning for ________, the prognosis is good.

A

24 hours

94
Q

Topical anesthesia

A

TETRACAINE, LIDOCAINE, COCAINE

*eutectic mixtures of local anesthetics lidocaine (2.5%)/prilocaine (2.5%) (EMLA) and lidocaine (7%)/tetracaine (7%) (PLIAGIS)

95
Q

__________ of mucous membranes decreases operative bleeding while improving surgical visualization

A

Shrinking

96
Q

Injection directly into tissue without taking into consideration the course of cutaneous nerves – skin to deeper structures

A

Infiltration anesthesia

97
Q

Infiltration anesthesia duration is increased by:

A

Epinephrine

98
Q

__________ - containing solutions should not be injected into tissues supplied by end arteries—for example, fingers and toes, ears, the nose, and the penis.

A

Epinephrine

99
Q

The resulting ________ may cause gangrene.

A

vasoconstriction

100
Q

subcutaneous injection in order to anesthetize the region distal to the injection

A

Field block anesthesia

  • scalp, anterior abdominal wall, upper & lower extremities
101
Q

Anesthesia of proximal portion of volar surface of forearm needs extensive anesthesia starting at ______ distal to the site of injection

A

2-3 cm

102
Q

_________ is never intentionally injected into the nerve, as this would be painful and could cause nerve damage.

A

Local anesthetic

103
Q

Instead, the __________ is deposited as close to the nerve as possible.

A

anesthetic agent

104
Q

When a local anesthetic is deposited about a peripheral nerve, it diffuses from the outer surface toward the core along a ___________.

A

concentration gradient

105
Q

Extremity is exsanguinated with an Esmarch (elastic) bandage and a proximally located tourniquet is inflated to __________ above the systolic blood pressure.

A

100-150 mm Hg

*INTRAVENOUS REGIONAL ANESTHESIA (BIER’S BLOCK)

106
Q

The Esmarch bandage is removed and the local anesthetic is injected into a previously cannulated vein

A

INTRAVENOUS REGIONAL ANESTHESIA (BIER’S BLOCK)

107
Q

Lidocaine without epinephrine

A

INTRAVENOUS REGIONAL ANESTHESIA (BIER’S BLOCK)

108
Q

surgery of the forearm & hand, foot & distal leg

A

INTRAVENOUS REGIONAL ANESTHESIA (BIER’S BLOCK)

109
Q

Injection of LA into subarachnoid space

A

Spinal anesthesia

110
Q

Spinal cord ends at ____.

A

L1 (above L2)

111
Q

Sympathetic blockade results to:

A

vasodilation (venous > arterial), hypotension

112
Q

At high levels of spinal blockade, the cardiac accelerator fibers which exit the spinal cord at T1-T4, will be blocked

A

bradycardia

113
Q

Decrease of BP to ~30% of resting values:

A

warrants treatment:

  1. O2
  2. fluid infusion (500-1000ml)
  3. manipulation of patient position
  4. administration of vasoactive drugs (ephedrine, phenylephrine)
114
Q

Neurological deficits (rare) :

A
  1. foreign substances (such as disinfectants or talc) into the subarachnoid space
  2. infection
  3. hematoma
  4. direct mechanical trauma
115
Q

Upright position

A

Postdural puncture headache

116
Q

Postdural puncture headache treatment:

A
  1. Conservative
  2. bed rest
  3. analgesics
  4. epidural blood patch
117
Q

Site of action of epidural anesthesia:

A

Spinal nerve roots

118
Q

requires higher dose than spinal anesthesia

A

Epidural anesthesia

119
Q

the level of sympathetic block is close to the level of sensory block

A

Epidural anesthesia