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pharm1 S.Horvath > local anesthetics > Flashcards

local anesthetics Flashcards

1
Q

local anesthetics are drugs that ____ block the conduction of electrical impulses along nerve fibers

A

reversibly

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2
Q

axolemma

A

cell membrane surrounding an axon

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3
Q

axoplasm

A

intracellular contents

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4
Q

schwann cells

A

produce myelin sheath, support and insulation

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5
Q

myelinated

A

have electrically insulating layer

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6
Q

Nodes of Ranvier

A

gap in myelin sheath, speeds propagation of action potentials, do not contain myeline.

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7
Q

saltatory conduction

A

the propagation of action potentials along myelinated axons from one node to the next, increasing conduction velocity of action potential. jumping node to node

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8
Q

fasciculi

A

bundle of axons (nerve fibers

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9
Q

endoneurium

A

layer of delicate connective tissue around the myelin sheath of each fiber

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10
Q

perineurium

A

middle layer, consists of layers of flattened, overlapping cells, binds a group of fascilices together

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11
Q

epineurium

A

outermost layer, made of connective tissue, holds fasiculli together

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12
Q

myelinated vs unmyelinated

A

myelinated are larger, conduct impulses faster, and are more difficult to block with LA than unmyelinated

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13
Q

order of layers inner to outer

A

endo, peri, epi

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14
Q

resting potential voltage?

A

-70MV

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15
Q

Na reverses membrane potential to

A

+35mv

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16
Q

resting membrane potential is restored by

A

active removal of intracellular Na+ by the Na/K pump (3/2)

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17
Q

local anesthetics ___ action potential

A

slow down

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18
Q

a-b-c

A

A is biggest, then B, then C

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19
Q

the only unmyelinated fibers

A

C fibers

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20
Q

C fibers are for pain and temp,

A

smallest and slowest

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21
Q

where are receptors for LA’s located

A

intracellular side of cell membrane

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22
Q

the receptors have a greater affinity for what form of the local anesthetics?

A

charged, ionized

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23
Q

to first penetrate the cell membrane, must be

A

non-ionized, uncharged state. weak bases

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24
Q

La are ___ in the physiologic pH and ___ inside the cell

A

basic, acidic

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25
Q

the sodium channel exists in what 3 ways

A

resting (closed) , activated (open) , inactivated

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26
Q

LA binds more easily to Na channel when it is

A

activated (open) or inactivated

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27
Q

the ___ portion of the LA is what makes them different and have implicates for metabolism and allergic potential

A

linkage

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28
Q

esters and amides have ___ structure which helps maintain lipophilicity

A

ring

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29
Q

the ____ all have the letter I in them

A

amides

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30
Q

change in ____ = change in duration of action

A

lipid solubility

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31
Q

LA with a pKa closest to physiologic ph will have a ___ concentration of non-ionized form that can readily pass thru the nerve cell membrane

A

higher

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32
Q

ion trapping

A

weak base in a very acidic environment will convert and become ionized and not be able to pass into the axon

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33
Q

ion trapping happens with injection into

A

acidic, infected tissues

34
Q

acidosis resulting from hypoxia may increase the ionized fraction of LA accumulation in

A

fetal circ

35
Q

highly lipid soluble = ___ duration of action

A

longer. fat likes fat. less likely to be cleared by blood flow

36
Q

onset of action isnt super variable among the LA’s but ___ is

A

duration

37
Q

1% solution =

A

1g/100ml

38
Q

all LA have ____ effects except for cocaine

A

vasodilatory

39
Q

the higher the concentration of drug injected that remain in the area of the nerves to be blocked, the ____ the onset of action

A

faster

40
Q

systemic absorption ___ from the tissue injection site results in the offset and termination of drug effect

A

AWAY

41
Q

the closer an LA is injected to a site of blood flow, the ___ it will discipate

A

faster

42
Q

the more fatty the area, the ___ the duration of action

A

longer

43
Q

you can add in a vasoconstrictor like epi to decrease

A

vascular absorption. (limits side effects, prolongs duration, enhances quality, increases nerve cell uptake)

44
Q

vasodilation from an LA ___ blood flow to the surrounding tissue where the drug is deposited

A

increases

45
Q

vasodilatory effects cause ___ absorption, ____ duration of action, and ___ toxicity

A

increased , reduced, increased

46
Q

greatest reservoir for LA?

A

muscle mass

47
Q

esters are metabolized by ____

A

pseudocholinesterase

48
Q

pseudocholinesterase do what

A

rapidly break down esters into water soluble metabolites that are excreted in urine (hydrophilic, ionized, kicked out by kidneys)

49
Q

esters and allergic reactions!!!!

A

procaine and benzocaine are metabolized to PABA (p-aminobenzoic acid)

50
Q

how are pt’s with genetically abnormal pseudocholinesterase at risk?

A

build up, longer duration, higher tox

51
Q

how are amides metabolized

A

CYP 450 enzymes in liver

52
Q

esters are metabolized ___ than amides

A

faster

53
Q

rate of metabolism of amides

A

prilo > lido > mevicao, > ropiva > bup. (pink lads move ropes best)

54
Q

decrease in liver function will reduce metabolism and increase toxicity of

A

amides

55
Q

risk of amides

A

prilocaine metabolites covert hb to methemoglobin.

56
Q

treat methemoglobinemia with

A

methylene blue

57
Q

methemoglobinemia causes

A

grey cyanotic, met acidosis, reduced o2 carrying capacity, significant in anemic or heart failure patient

58
Q

what two things influence toxicity greatly

A

absorption and metabolism

59
Q

the ___ a local is absorbed into the vascular space, the ___ likely that high blood levels and CNS toxicity will occur

A

slower, less

60
Q

what can you add to LA’s

A

opiates, sodium bicarb, epi

61
Q

what causes systemic toxicity?

A

inadvertent intravascular injection, administration of excessive dose

62
Q

cardiocirc tox.. first you see

A

htn tachy (matching vasodilatory effects)

63
Q

cardiocirc tox.. second you see

A

brady, extrasystoles, hypotension

64
Q

cardiocirc tox.. lastly you see

A

asystole

65
Q

cerebral tox.. first you see

A

psych abnormal

66
Q

cerebral tox.. second you see

A

confusion, dizziness, tinnitus, metalic taste

67
Q

cerebral tox.. last you see

A

seizures

68
Q

which system is more resistant to tox of LA

A

CV

69
Q

all LA ___ myocardial automaticity and ____ duration of refractory period

A

depress, reduce

70
Q

high blood levels of LA will __ contractility and conduction

A

depress

71
Q

LA’s produce smooth muscle ___ and arteriolar ____

A

relaxation, vasodilation

72
Q

which drug is known for cardio tox

A

bupivacaine

73
Q

what can you give for cardio tox

A

lipid rescue 10-30% solution, binds up with other lipids

74
Q

dysesthsia, burning, pain and aching in lower extremity and buttocks associated with

A

lido

75
Q

eutectic mixture

A

topical , on intact skin. lipophilic

76
Q

EMLA

A

lido and prilo. takes 1 hr

77
Q

why shouldn’t you put topicals on thin mucous membranes or areas with lot of bloodflow

A

cause damage, tox, increased absoption

78
Q

cocaine is used for

A

vasoconstriction for ENT cases

79
Q

a fibers

A

large, myelinated, motor function and proprioception. not as sensitive.. need more LA.

80
Q

B fibers

A

pregang autonomic nerves

81
Q

C fibers

A

small, unmyelinated, slow. most susceptible to LA.

pharm1 S.Horvath (18 decks)

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