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ANPH 510 pharm 2 mccarver > Local Anesthetics > Flashcards

Local Anesthetics Flashcards

0
Q

Local anesthetics are poorly __ soluble unless prepared as HCl salts

A

water

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1
Q

What is the Gold Standard of Local Anesthetics?

A

Lidocaine

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2
Q

HCl salts contribute to local anesthetic __

A

stability

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3
Q

LA’s containing epi may have pH lowered to __ with sodium bisulfate

A

4.0

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4
Q

Lower pH’s prevent oxidative decomposition of __

A

epinephrine

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5
Q

the hydrophilic portion of LA’s is a tertiary __

A

amine

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6
Q

the lipophilic portion is an unsaturated aromatic ring like __

A

PABA

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7
Q

is the lipo or hydrophilic portion essential for anesthetic activity?

A

lipo-philic, because it can pass the lipid bilayer

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8
Q

what does an ester linkage look like?

A

-CO-

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9
Q

what does an amide linkage look like?

A

-NHC-

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10
Q

Name all the esters

the one eyed ester bunny

A

Chloe drank four coke’s like a pro

Chloro Tetra Cocaine Procaine

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11
Q

Pipecoloxylidides like mep, bup, and rop are __ molecules that have assymetric carbon atoms and result in both left and right handed configurations.

A

chiral

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12
Q

“S” enantiomers are __ than “R” enantiomers which are __

A

“S”safer

“R”risky

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13
Q

How do LA’s work?

A

inhibit passage of sodium ions through channels in nerve membranes

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14
Q

LA binding to sodium channels is __ specific

A

stereo

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15
Q

sodium channels are __ when activated AND closing

A

open

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16
Q

sodium channels are __ when OPENING and RESTING

A

CLOSED

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17
Q

resting is an equilibrium between __-closed and __-closed

A

rested-closed and inactivated-closed

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18
Q

LA’s work on sodium channels in the __ open and __ closing states

A

final open

intermediate closing

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19
Q

Sodium channels partially recover from LA blockade BETWEEN action potentials, but LA’s strengthen their blockade each time sodium channels open DURING subsequent action potentials

A

recover between AP’s but

deeper block with subsequent AP’s

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20
Q

the more actively firing a nerve, the easier it is to block. again, LA’s have easiest access to sodium channels in the __ open and __ closing states

A

final open

intermediate closing

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21
Q

Cm = MAC for local anesthetics

A

minimum concentration needed to block

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22
Q

bigger nerves have __ Cm

A

bigger

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23
Q

Acidic tissues have __ Cm

A

higher

24
Q

how does pKa affect Cm?

A

the further the pKa from physiologic pH, the more Cm you’re gonna need.

25
Q

Faster firing nerves have __ Cm’s

A

lower

because there are more opportunities for the LA to block when the channels are constantly opening and closing.

26
Q

motor fibers have 2x the Cm of sensory fibers so…

A

you’re gonna need twice the LA to block motor as you do to block sensory

27
Q

how many nodes of ranvier must be blocked for adequate conduction blockade?

A

2-3

28
Q

pain fibers (A delta and C) require similar Cm’s for blockade, but B fibers (sympathethic) require less

A

so you’re gonna knock out the sympathetic nervous system before you block the pain signals

29
Q

In order, what tissues are LA’s absorbed and metabolized into first to last

A 
lungs
VRG
skeletal muscle
fat
metabolism
elimination
30
Q

the greater the protein binding, the __ the plasma drug concentrations

A

lower, because all of the drug is going to be bound up and none will be available.

31
Q

who has greater systemic absorption, amides or esters?

A

amides

what do you use for bier blocks? lidocaine which is an amide for better absorption

32
Q

the greater the protein binding, the __ can transfer through the placenta

A

less, because it’s all bound up and too big to fit through the placenta.

33
Q

you don’t even have to worry about esters crossing the placenta because__

A

hydrolyze very quick, ester hydrolysis.

34
Q

how do amides metabolize?

A

hepatic microsomal enzymes
prilocaine fast
lido/mepi middle
etido, bup, rop slooooow

35
Q

is systemic toxicity more likely with amides or esters?

A

amides, because esters under quick ester hydrolysis

36
Q

what’s so special about prilocaine?

A

metabolite orthotoulidine can convert hemoglobin to methemoglobin
-give methylene blue

37
Q

what is the most slooooowly eliminated amide?

A

dibucaine

that’s why we use a dibucaine number to define a person with atypical plasma cholinesterase

38
Q

why should you consider tetracaine if you want a really loooong acting spinal?

A

CSF lacks cholinesterase, so the block will last until it is systemically absorbed.

39
Q

what is the cause of most allergic reactions to LA’s

A

the ester bunny’s papa

ester metabolite PABA

40
Q

patient allergic to esters may receive amides

A

and vice versa

41
Q

what is the number one cause of systemic toxicity?

A

intravascular injection - duh

42
Q

systemic absorption from greatest to least

A

intercostal
epidural
brachial plexus

ribs, spine, arms
ieb - in emergency break glass

43
Q

the lower the PaCO2, the higher the seizure threshold, so_

A

hyperventilate your patient

44
Q

hyperkalemia (as in end stage renal pt in for shunt revision) has a higher probability of seizing.

A

don’t try a block with a K of 7.0 and a biphasic qrs

45
Q

transient radicular irritation symptoms usually disappear in one __

A

week

46
Q

__ has a lower incidence of transient radicular irritation than lido

A

bup

47
Q

hyperbaric 5% lido is the LA implicated in the horse’s tail

A

cauda equina from 5% lido

48
Q

high doses of LA’s produce hypotension due to __ and __ by blocking sodium channels and decreasing cAMP

A

arteriolar relaxation and myocardial depression

49
Q

limit epidural bup concentrations to ___% due to cardiac toxicity

A

0.5% bup, pretty standard concentration of bup

50
Q

can you use EMLA cream on someone with methemoglobinemia?

A

Nope, cause it’s prilo and lido

51
Q

LA’s diffuse from the mantle (outside) to the core (center). Are fibers in the mantle proximal or distal

A

proximal, they are added to the top layer as the nerve ascends to the spinal cord, thus anesthesia develops proximally and spreads distally

52
Q

what LA’s can you use for bier block

A

lido or prilo, same as in EMLA cream

53
Q

during epidural, the motor blockade may extend 4 segments __ the block

A

below

54
Q

for spinals, the SNS block may extend 2 segments __ than the sensory block, but the motor block may extend 2 segments __ than the sensory block

A

SNS 2 segments higher

motor 2 segments lower

55
Q

even though capacitance vessel dilation does occur below the level of spinal anesthesia, compensatory vasoconstriction occurs in the upper extremities and DOES NOT involve the central vasculature

A

DOES NOT

56
Q

__ circulation alterations are the most important physiologic events occurring with spinals

A

venous

because unlike arterioles, they cannot maintain intrinsic tone. SO tank em up first with a liter or two

57
Q

where are the cardiac accelerators?

A

T1-T4

58
Q

what is the bainbridge reflex?

A

decreased venous return = lower heart rate

I know it doesn’t make any sense, that just the way it is.

ANPH 510 pharm 2 mccarver (7 decks)

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