Local Anesthesia Flashcards
3 parts of local anesthesia
aromatic group
intermediate linkage
amine group
aromatic group
lipophilic properties
intermediate linkage
spacial separation between lipophilic and hydrophilic ends
connects them with ester or amide
amine group
affects pKa and speed of onset
difference between amide and ester
amide - union of carboxylic acid and amine (peptide bond is amide)
ester -union of carboxylic acid and alcohol
except for procaine, all injectable dental locals are (amines or esters)
amines
topicals are mostly (amines or esters)
esters
the amine portion is the ____
base
what is special about free bases?
the amine portion is a free base
only free bases can cross the cell membranes, so onset of action is faster for lower pKa’s (stronger acids) because they give up their protons more easily and become uncharged “free bases”
onset is faster for ____
low pKa’s (strong acids)
acidic environments like inflamed tissue…
have slow onset, since the base remains protonated in the low pH environment (impedes local anesthesia development)
locals stabilize ________
membranes
decrease rate of depolarization and repolarization
locals prevent _____
rapid sodium influx
needed to make an AP
why are the pharmacokinetics of locals unique?
they become ineffective when absorbed into the system / blood stream
local anesthetics wear off when…
redistributed throughout the body to all tissues (when the numbness goes away)
metabolic half life is not related to _________ but is related to ______
duration of anesthesia
toxicity
why does metabolism affect overall toxicity?
because it’s balance between rates of absorption at injection site and rate of removal from the blood
duration of action is related to _____ (not _______)
protein bonding of local
metabolic transformation
locals are all (vasoconstrictors or vasodilators)
vasodilators
which local anesthetic is not a vasodilator? (exception!)
cocaine!
what is needed in locals to slow the distribution?
vasoconstrictors
_____ anesthesia takes the longest to develop (and leaves first)
pulpal
which type of anesthesia lasts longest? Nerve blocks or infiltration?
nerve blocks
primary site of metabolism for amides
liver
excretion of LA
kidney for LA agents and metabolites
when do local anesthetics lose their effect?
when they are absorbed into the bloodstream
rate at which local is removed from the plasma is expressed as its
metabolic half life
duration of action of local anesthetics (shortest to longest) in terms of type of tissue
shortest = pulpal anesthesia
longest = soft tissue anesthesia
duration of action of local anesthetics (shortest to longest) in terms of type of LA
carbocaine (mepivacaine)
xylocaine (lidocaine)
septocaine (articaine)
marcaine (bupivacaine)
which anesthetic is not recommended in pedo or in cognitiviely impaired adults?
marcaine (bupivacaine)
methamoglobin
hemoglobin in which the iron ion has been oxidized to the ferric instead of the ferrous state
does not bind O2
methamoglobin is produced by which local
articaine / prilocaine
max does for lidocaine with epi
4.4 mg / kg per malamed
max dose for mepivacaine
4.4 mg / kg
max dose for bupivicaine
1.3 mg / kg
max dose for septocaine
7mg / kg
epinephrine max recommended dose for non-cardiac patient
0.2 mg
epinephrine max recommended dose for cardiac patient
0.04 mg
lidocaine 2% has 34 mg of local in carpule. what is do
