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.Pharmacology > Chapter 21: Local Anesthetics > Flashcards

Chapter 21: Local Anesthetics Flashcards

1
Q

local anesthetics work by blocking ___channels to prevent transmission of painful stimulus

A

Na

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2
Q

voltage gated Na channels open when the membrane ___

A

depolarizes

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3
Q

t/f when the inactivation gate of the Na channel is close, the channel cannot be reopened

A

t

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4
Q

when the membrane re-polarizes, the inactivation gate ___ in preparation for next depolarization

A

relaxes

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5
Q

inactivation gates of na channels prevent prolonged ___

A

depolarization

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6
Q

why would it be dangerous to block all the Na channels?

A

not just found in neurons, also in skeletal muscle and cardiac muscle, so the heart and diaphragm wouldn’t contract and we would die

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7
Q

what is Tetrodotoxin? what does it do?

A

natural toxin found in puffer fish; blocks many na channels and can be fatal at low doses

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8
Q

what dose of tetrodotoxin is fatal in an adult human?

A

10-25mg

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9
Q

how can tetrodotoxin be used in research of cellular processes?

A

blocking Na channels makes it easier to observe other processes

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10
Q

t/f there is no therapeutic use for tetrodotoxin

A

t

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11
Q

local anesthetics block the Na channels of ___(small/large) diameter nerve fibers more effectively

A

small

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12
Q

the neurons that carry pain signals are ____ in diameter

A

small

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13
Q

small neurons like ____ can be the target of off-target effects of local anesthetics, but large neurons like ___ cannot

A

autonomic neurons; motor neurons

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14
Q

t/f if the concentration of local anesthetic is high enough, large diameter neurons can be blocked

A

t

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15
Q

the primary principle of local anesthetics is that they are administered to the local area where ____ is wanted

A

nerve block

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16
Q

local anesthetics allow for high ____ while having reduced risk of ___

A

drug concentration; systemic effects

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17
Q

the effect of local anesthetic is ___ as the effect is reduced as the drug diffuses away from the local site

A

transient

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18
Q

what is unique about epidurals and spinal blocks in terms of being local anesthetics

A

the anesthetic is not injected at the site that will feel pain, but rather to the area of the spinal cord that houses the nerves for that area

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19
Q

local anesthetics are relatively simple molecules that have what 3 parts?

A

lipophilic, hydrophilic, linker

20
Q

local anesthetics are divided into 2 groups based on their linking groups: ___ and ___ type agents

A

ester and amide

21
Q

cocaine is a ___ type local anesthetic

A

ester

22
Q

procaine is___ local anesthetic that was developed based on discovery of cocaine as an anesthetic

A

prototypic ester

23
Q

why are other agents used more frequently than procaine?

A

it has a short duration of action

24
Q

Benzocaine is a ___type anesthetic that is administered by the ___ route

A

ester; topical

25
Q

t/f benzocaine is used in many creams to treat sunburn pain

A

t

26
Q

the ester bonds of benzocaine are cleaved by ___

A

esterases

27
Q

esterases can ___ the duration of action of ester local anesthetics

A

shorten

28
Q

lidocaine and bupivacaine are ___ type anesthetics

A

amide

29
Q

amide anesthetics are used more often bc

A

they cant be craved by esterase’s, so have longer duration of action

30
Q

___ is one of the common agents used in epidurals for childbirth

A

bupivacaine

31
Q

compare the duration of action for lidocaine vs bupivacaine and what they are useful for

A

lidocaine has a moderate duration and useful in dental procedures; bupivacaine has longer duration and used in surgery and child birth

32
Q

local anesthetic bind to what part of the Na channel?

A

inside of the pore

33
Q

do local anesthetics pass through the Na channels?

A

NO

34
Q

how do local anesthetics gain access to the inside of the Na channel w/o passing through the pore?

A

cross the cell membrane and access binding site from the inside

35
Q

the ionized form of local anesthetics has a ___ affinity for the binding site

A

greater

36
Q

t/f local anesthetics having lipophilic and hydrophilic parts help them cross the cell membranes to act on the channels

A

t

37
Q

the hydrophilic parts of the local anesthetics have a ___ group that can be protonated depending on pH

A

tertiary nitrogen

38
Q

when the pH and PKa are the same, there is a ____ split between charged and uncharged local anesthetics

A

50-50

39
Q

the pka of lidocaine is 7.8, so at physiologic pH, there is a near ___ spilt of charged and uncharged drug

A

50/50

40
Q

the ___ (charged / uncharged) form of local anesthetic is able to cross the membrane

A

uncharged

41
Q

t/f bc the uncharged form of local anesthetic crosses through to the membrane so the equilibrium is thrown off

A

t

42
Q

the effects of local anesthetics are stopped when the drug diffuses away from the Na channel which can then

A

return to resting closed state to await depolarization

43
Q

t/f blood flow easily carries local anesthetic away from site of admisntration

A

t

44
Q

the ADRs of local anesthetics are ___ dependent

A

dose

45
Q

if local anesthetics get too much into systemic circulation, they can cause

A

respiration and cardiac arrest and death q

46
Q

t/f repeated dosing of anesthetic is only given when necessary

A

t

47
Q

how can the duration of action of a local anesthetic at its local site be prolonged w/o adding more anesthetic?

A

add a vasoconstrictor like epi prevents drug from flowing through local BV away from admin site

.Pharmacology (55 decks)

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