Local Anesthetics Flashcards
what characteristic of local anesthetics allows them to cross cell membranes
they’re amphipathic- both lipophilic and hydrophilic characteristics
are ester linked or amide linked local anesthetics more prone to rapid hydrolysis and inactivation
ester
are ester linked or amide linked local anesthetics at high risk for causing hypersensitivity
ester
are ester linked or amide linked local anesthetics used more on mucous surfaces
ester
what is the mechanism of action of local anesthetics
bind with cytoplasmic receptors and inhibit VGNaC, prolonging the channel in the inactive form
do local anesthetics have high affinity for resting, activated, or inactivated VGNaC
inactivated
the effects of local anesthetics are pronounced in __ and not in __
in rapidly firing axons
not in resting neurons
how many nodes of ranvier are sufficient to induce local anesthesia
2-3
does an increase in extracellular calcium increase of decrease the effects of local anesthesia
increase
tetrodotoxin comes from __
puffer fish
saxitoxin comes from __
algae
ciguatoxin comes from __
exotic fish
batrachotoxin comes from __
frogs
what is the order of blockage between motor, sensory, and autonomic fibers
autonomic first, then sensory and motor
what is the order of recovery between motor, sensory, and autonomic fibers
motor, sensory, then autonomics
are smaller or larger fibers more sensitive to blockade
small
are myelinated or unmyelinated fibers more sensitive to blockade
myelinated
what fibers, A/B/C, are affected first due to their response to low concentration of local anesthetic
B
what is an example of a differential blockade in which local anesthetics block sensory impulses while sparing motor and proprioception
labor analgesia
diffusion of local anesthetics is in the __ (unionized basic or charged) form, which is then converted to the __ (unionized basic or charged) form inside the axon
diffusion= unionized basic
converted to charged
what is the relationship between local anesthetic effect and inflammation
inflammation produces lactic acid products. acidification of tissues slows the local anesthetic effectiveness
the anesthetic becomes charged and is unable to penetrate the nerve cell membrane
what can be done to eliminate the effect of increased acidity with inflammation when giving a local anesthetic
enhance with sodium bicarbonate to increase the pH
amide linked local anesthetics use is cautioned in those with __, __, and those taking __
hepatic disease
congestive heart failure
beta blockers
local anesthetics have drug-drug interaction with what 2 classes of drug
alpha 2 agonist
opioids
the duration of action of local anesthetics is proportional to ))
the duration of contact with the nerves
what can be used to prolong the effect of local anesthetics
vasoconstrictors
vasoconstrictors with local anesthetic use is contradicted in procedures involving what body sites
tip of nose
feet
toes
penis
fingers
what is the effect of local anesthetic use on the CNS
stimulation then depression
what is the mechanism of action of cocaine as a local anesthetic
blocks reuptake of NE
causes vasoconstriction
what local anesthetic is used in the ocular and tracheobronchial regions to reduce bleeding
cocaine
is cocaine lipid soluble?
does cocaine have a high or low potency?
lipid soluble
high potency
procaine is a local anesthetic with a lower potency and shorter course of action as compared to cocaine. procaine reduces the effect of what drug class
sulfonamides
what local anesthetic is used as an antiarrhythmia and is the drug of choice in ventricular fibrillation following MI
lidocaine
in what cases with a vasoconstrictor now be used with a local anesthetic
during cases of arrhythmia, as vasoconstrictors can worsen arrhythmias
what local anesthetic is long acting and produces more sensory block and motor block, thus being preferred during labor
Bupivacaine
Bupivacaine causes more __ but less __
more cardiotoxicity
less nephrotoxicity
what local anesthetic has less risk for transient neurologic symptoms
Bupivacaine
what local anesthetic should be avoided in pregnancy
Mepivacaine
how does Prilocaine differ from lidocaine
it can be used without a vasoconstrictor
it’s used for IV regional block
what 2 drugs make up Eutectic Mixture of LAs (EMLA)
lidocaine
Prilocaine
Eutectic Mixture of LAs (EMLA) is effective for __ but should not be used for __
effective for procedures involving skin and superficial tissue
not effective for mucous membranes or abraded skin
where is the local anesthetic injected into with spinal anesthesia
subarachnoid space
what is the limitation with spinal anesthesia
duration is only 1-4 hours
what is one main initial CNS symptom of local anesthetic system toxicity
tongue paralysis
local anesthetic system toxicity can present with __ and __
tonic clonic seizures
respiratory depression
what are 2 ways in which local anesthetic system toxicity is treated
IV diazepams for seizures
succinylcholine to suppress muscle reactions
what local anesthetic is the most cardiotoxic
Bupivacaine
