CNS Drugs: Anesthetics

Question 1

What route of anesthesia?

injection into CSF in
lumbar region;

Blocks sympathetic fibers in
the subarachnoid space

Answer 1

spinal

Question 2

Which type of local anesthetic?

shorter duration

increased systemic toxicity

Answer 2

Esters

Question 3

LAs must be ______ to cross the cell membrane

Answer 3

non-ionized

Question 4

To bind to the sodium channel, LAs must be ______. this happens where?

Answer 4

ionized, happens inside cell

Question 5

at physiologic pH of 7.4, LAs are typically in what form?

Answer 5

ionized

Question 6

where is the binding site for LAs on the sodium channel?

Answer 6

inner membrane

Question 7

in general the closer the pKa is to physiologic pH, the higher the conc. of drug in the ______ form

Answer 7

non-ionized

Question 8

pKa close to 7.4 means what for membrane transport?

Answer 8

faster

Question 9

Lidocaine pKa is 7.8, bupivacaine is pKa 8.1… which will have a faster onset?

Answer 9

lido

Question 10

which LA is always in the non-ionized form, with the pKa of 3.5

Answer 10

benzocaine

Question 11

_______ can make pH more basic and therefore increase non-ionized concentrations and degree of LA transport

Answer 11

bicarb

Question 12

LAs exhibit state-dependent blockade, which means they target channels in what states

Answer 12

open and inactivated states (rapidly firing axons)

Question 13

What effect does increased calcium have on LA activity?

Answer 13

diminished effects 
(hyperpolarized, more resting state channels)

Question 14

What effect does increased potassium have on LA activity?

Answer 14

enhanced effects (depolarized, more active)

Question 15

The below have what potency/lipid solubility compared to procaine, and what duration?

tetracaine
bupivacaine
ropivacaine

Answer 15

Long acting

16x potency

Question 16

The below has what potency/lipid solubility compared to procaine?

lidocaine

Answer 16

4x

Question 17

The below have which duration of action compared to procaine?

cocaine
mepivacaine
lidocaine

Answer 17

medium acting

Question 18

The below have what potency/lipid solubility compared to procaine?

cocaine
mepivacaine

Answer 18

2x

Question 19

procaine is ____ acting

Answer 19

short

Question 20

Toxic effects of LAs (CNS, cardiac) depend on…

Answer 20

half-life

Question 21

Concurrent use of ____ along LAs has the below effects

•
Decreases diffusion of drug
•
Prolongs duration of action
•
Decreases systemic absorption
•
Decreases risk of systemic toxicity

Answer 21

vasoconstrictors

Question 22

Which type of LAs?

•
Metabolized in the liver by the CYP450s
•
Toxicity is more likely in patients with hepatic disease or
reduced hepatic blood flow

Answer 22

amides

Question 23

Which type of LAs?

•
Rapidly metabolized by butyrylcholinesterases in the
plasma
•
Mutations can affect metabolism of these LAs

Answer 23

esters

Question 24

What is the order of sensitivity of LA effects?

Answer 24

SNS > pain > touch > motor

Question 25

This happens when a block is not limited to the intended site. it can lead to motor paralysis, respiratory impairment, hypotension

Answer 25

differential block

Question 26

____ fibers are more sensative than large ones

Answer 26

small diameter (B/C)

Question 27

Myelinated or unmyelinated fibers of similar diameter are more or less sensitive?

Answer 27

myelinated (type delta) less sensitive

Question 28

the _____ the conduction velocity, the less sensitive. Meaning motor fibers are less sensitive than pain

Answer 28

faster conduction = less sensitive

Question 29

Which LA has the following SE/Toxicity? increased binding to cardiac Na channels, slower dissociative times

Answer 29

bupivacaine

Question 30

What can help decrease cardiotoxicity of LAs?

Answer 30

IV lipid administration

Question 31

Cardio effects of LAs are...

Answer 31

arrhythmia, vasodilation, hypotension

Question 32

The depression of cortical inhibitory pathways can lead to...

Answer 32

severe CNS sxs, TNS

Question 33

allergic reactions are often due to PABA, which is a metabolite of which class?

Answer 33

Esters

Question 34

Which LA can produce methemoglobinemia?

Answer 34

prilocaine

Question 35

Which LA? metabolized to PABA (allergy & sulfa inhibition) Used for infiltration anesthesia

Answer 35

procaine

Question 36

Which LA? preferred for ophthalmologic use spinal anesthesia with 10% dextrose severe toxicity w. high volume peripheral blocks

Answer 36

tetracaine

Question 37

Which LA? topical only high risk methemoglobinemia

Answer 37

benzocaine

Question 38

Which LA? Rapid onset anesthesia Preferred for infiltration blocks and epidural not used for Spinal Blocks

Answer 38

lido

Question 39

why isn't lido used for spinal blocks?

Answer 39

risk of TNS

Question 40

Which LA? highest rate of clearance of amides can cause methemoglobinemia largely limited to dentistry

Answer 40

prilocaine

Question 41

This has more potent sensory block than motor block. is used for epidural during labor and childbirth

Answer 41

bupivacaine

Question 42

which amide has greatest cardiotoxicity and diffuses away from cardiac channels slowly?

Answer 42

bupivacaine

Question 43

This is an S-enantiomer of bupivacaine that is less lipid soluble and cleared more rapidly

Answer 43

ropivacaine

Question 44

what advantages does ropivacaine have against bupivacaine?

Answer 44

less adverse effects, less cardiotoxic

Question 45

ropivacaine is used for...

Answer 45

peripheral/epidural

Question 46

which amide is vaso-constricting at clinical doses?

Answer 46

ropivacaine

Question 47

Mepivacaine is not used for...

Answer 47

labor

Question 48

etidocaine is the opposite of bupivacaine in that it causes...

Answer 48

motor block before sensory block (differential block)

Question 49

Which LA contains both amide and ester group?

Answer 49

articaine

Question 50

the ester group on articaine renders it open to metabolism by...

Answer 50

plasma esterases

Question 51

Where is articaine used?

Answer 51

dentistry

Question 52

The dibucaine number test measures activity of _______ to differentiate individuals with mutations and deficiency

Answer 52

butyrylcholinesterase

Question 53

dibucaine (induces/inhibits) wild type butyrylcholinesterase

Answer 53

inhibits