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pharm1 S.Horvath > local anesthetics > Flashcards

local anesthetics Flashcards

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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
the sodium channel exists in what 3 ways
resting (closed) , activated (open) , inactivated
26
LA binds more easily to Na channel when it is
activated (open) or inactivated
27
the ___ portion of the LA is what makes them different and have implicates for metabolism and allergic potential
linkage
28
esters and amides have ___ structure which helps maintain lipophilicity
ring
29
the ____ all have the letter I in them
amides
30
change in ____ = change in duration of action
lipid solubility
31
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
higher
32
ion trapping
weak base in a very acidic environment will convert and become ionized and not be able to pass into the axon
33
ion trapping happens with injection into
acidic, infected tissues
34
acidosis resulting from hypoxia may increase the ionized fraction of LA accumulation in
fetal circ
35
highly lipid soluble = ___ duration of action
longer. fat likes fat. less likely to be cleared by blood flow
36
onset of action isnt super variable among the LA's but ___ is
duration
37
1% solution =
1g/100ml
38
all LA have ____ effects except for cocaine
vasodilatory
39
the higher the concentration of drug injected that remain in the area of the nerves to be blocked, the ____ the onset of action
faster
40
systemic absorption ___ from the tissue injection site results in the offset and termination of drug effect
AWAY
41
the closer an LA is injected to a site of blood flow, the ___ it will discipate
faster
42
the more fatty the area, the ___ the duration of action
longer
43
you can add in a vasoconstrictor like epi to decrease
vascular absorption. (limits side effects, prolongs duration, enhances quality, increases nerve cell uptake)
44
vasodilation from an LA ___ blood flow to the surrounding tissue where the drug is deposited
increases
45
vasodilatory effects cause ___ absorption, ____ duration of action, and ___ toxicity
increased , reduced, increased
46
greatest reservoir for LA?
muscle mass
47
esters are metabolized by ____
pseudocholinesterase
48
pseudocholinesterase do what
rapidly break down esters into water soluble metabolites that are excreted in urine (hydrophilic, ionized, kicked out by kidneys)
49
***esters and allergic reactions!!!!***
procaine and benzocaine are metabolized to PABA (p-aminobenzoic acid)
50
how are pt's with genetically abnormal pseudocholinesterase at risk?
build up, longer duration, higher tox
51
how are amides metabolized
CYP 450 enzymes in liver
52
esters are metabolized ___ than amides
faster
53
rate of metabolism of amides
prilo > lido > mevicao, > ropiva > bup. (pink lads move ropes best)
54
decrease in liver function will reduce metabolism and increase toxicity of
amides
55
**risk of amides**
prilocaine metabolites covert hb to methemoglobin.
56
treat methemoglobinemia with
methylene blue
57
methemoglobinemia causes
grey cyanotic, met acidosis, reduced o2 carrying capacity, significant in anemic or heart failure patient
58
what two things influence toxicity greatly
absorption and metabolism
59
the ___ a local is absorbed into the vascular space, the ___ likely that high blood levels and CNS toxicity will occur
slower, less
60
what can you add to LA's
opiates, sodium bicarb, epi
61
what causes systemic toxicity?
inadvertent intravascular injection, administration of excessive dose
62
cardiocirc tox.. first you see
htn tachy (matching vasodilatory effects)
63
cardiocirc tox.. second you see
brady, extrasystoles, hypotension
64
cardiocirc tox.. lastly you see
asystole
65
cerebral tox.. first you see
psych abnormal
66
cerebral tox.. second you see
confusion, dizziness, tinnitus, metalic taste
67
cerebral tox.. last you see
seizures
68
which system is more resistant to tox of LA
CV
69
all LA ___ myocardial automaticity and ____ duration of refractory period
depress, reduce
70
high blood levels of LA will __ contractility and conduction
depress
71
LA's produce smooth muscle ___ and arteriolar ____
relaxation, vasodilation
72
which drug is known for cardio tox
bupivacaine
73
what can you give for cardio tox
lipid rescue 10-30% solution, binds up with other lipids
74
dysesthsia, burning, pain and aching in lower extremity and buttocks associated with
lido
75
eutectic mixture
topical , on intact skin. lipophilic
76
EMLA
lido and prilo. takes 1 hr
77
why shouldn't you put topicals on thin mucous membranes or areas with lot of bloodflow
cause damage, tox, increased absoption
78
cocaine is used for
vasoconstriction for ENT cases
79
a fibers
large, myelinated, motor function and proprioception. not as sensitive.. need more LA.
80
B fibers
pregang autonomic nerves
81
C fibers
small, unmyelinated, slow. most susceptible to LA.

pharm1 S.Horvath (18 decks)

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