LOCAL ANESTHESIA CORE MAIN EXAMINATION
QUESTIONS AND ANSWERS SURE A+
✔✔lipophilic vs. hydrophyllic - ✔✔lipophilic is lipid soluble and hydrophyllic is water
soluble
✔✔what makes the terminal amine so important to the structure of local anesthetic? -
✔✔this allows the local anesthetic to the both lipid soluble and water soluble at the
apporpriate times (ex: hydrophyllic for dilution and pH control; lipophyllic in order to
penetrate neuron cell membrane; hydrophyllic to block Na+ channels)
✔✔what is pKa and what does it do? - ✔✔the dissociation constant - this identifies the
pH at which the anesthetic exists in a 50/50 ratio of the ionized to non-ionized
(hydrophyllic to lipophyllic) molecules
✔✔lipid solubility of local anesthetics - ✔✔the different structure of the various
anesthetics confers varying degrees of lipid solubility (the greater the lipid solubility of
the basic molecule the more potent it is)
✔✔protein binding of local anesthetics - ✔✔the greater degree of protein binding, the
more molecules you have waiting in reserve for later action (the more proteins bound,
the longer the duration)
, ✔✔vasodilation and the local anesthetics - ✔✔with the exception of cocaine, all
anesthetics are vasodilators (undesirable as this promotes quicker vascular
uptake/metabolism and therefore less anesthetic action)
✔✔what is biotransformation? - ✔✔metabolism
✔✔where are amides metabolized and where are esters metabolized? - ✔✔amides:
liver (in order to be rendered water soluble so that they can be excreted in the kidneys)
esters: plasma by cholinesterase (more rapid than hepatic leading to shorter duration)
✔✔what is the only amide anesthetic that also contains an ester group, and how is it
metabolized? - ✔✔Articaine (septocaine) this agent is metabolized both hepatically and
by plasma cholinesterase
✔✔ester onset and duration - ✔✔slow onset with short duration
✔✔amide onset and duration - ✔✔fast onset and longer duration
✔✔are esters or amides more likely for toxicity? - ✔✔esters are more likely to cause
toxicity
✔✔what does NaCl do to the anesthetic solutions? - ✔✔makes the solution isotonic
✔✔what does HCL do to the anesthetic solutions? - ✔✔lower the pH for the addition of
epinephrine
✔✔what does epinephrine do the the anesthetic solutions? - ✔✔reduce absorption
rates at site of injection (increase duration/reduce blood levels - toxicity)
✔✔what do bisulfites do to the anesthetic solutions? - ✔✔reduce the oxidation of the
epinephrine (longer shelf-life)
✔✔what does methylparaben do to the anesthetic solutions? - ✔✔agent used for its
antibacterial action that is no longer contained in dental cartridges, only in multiple dose
vials
✔✔what are all of the effects that result when epinephrine is added to a solution? -
✔✔increased heart rate, increased systolic pressure, lowers diastolic pressure
✔✔what is the MCD (maximum cardiac dose) of epinephrine? - ✔✔0.04 mg (40ug)
✔✔what are the available options for lidocaine? - ✔✔2% either with 1:100,000 or
1:50,000 epi
QUESTIONS AND ANSWERS SURE A+
✔✔lipophilic vs. hydrophyllic - ✔✔lipophilic is lipid soluble and hydrophyllic is water
soluble
✔✔what makes the terminal amine so important to the structure of local anesthetic? -
✔✔this allows the local anesthetic to the both lipid soluble and water soluble at the
apporpriate times (ex: hydrophyllic for dilution and pH control; lipophyllic in order to
penetrate neuron cell membrane; hydrophyllic to block Na+ channels)
✔✔what is pKa and what does it do? - ✔✔the dissociation constant - this identifies the
pH at which the anesthetic exists in a 50/50 ratio of the ionized to non-ionized
(hydrophyllic to lipophyllic) molecules
✔✔lipid solubility of local anesthetics - ✔✔the different structure of the various
anesthetics confers varying degrees of lipid solubility (the greater the lipid solubility of
the basic molecule the more potent it is)
✔✔protein binding of local anesthetics - ✔✔the greater degree of protein binding, the
more molecules you have waiting in reserve for later action (the more proteins bound,
the longer the duration)
, ✔✔vasodilation and the local anesthetics - ✔✔with the exception of cocaine, all
anesthetics are vasodilators (undesirable as this promotes quicker vascular
uptake/metabolism and therefore less anesthetic action)
✔✔what is biotransformation? - ✔✔metabolism
✔✔where are amides metabolized and where are esters metabolized? - ✔✔amides:
liver (in order to be rendered water soluble so that they can be excreted in the kidneys)
esters: plasma by cholinesterase (more rapid than hepatic leading to shorter duration)
✔✔what is the only amide anesthetic that also contains an ester group, and how is it
metabolized? - ✔✔Articaine (septocaine) this agent is metabolized both hepatically and
by plasma cholinesterase
✔✔ester onset and duration - ✔✔slow onset with short duration
✔✔amide onset and duration - ✔✔fast onset and longer duration
✔✔are esters or amides more likely for toxicity? - ✔✔esters are more likely to cause
toxicity
✔✔what does NaCl do to the anesthetic solutions? - ✔✔makes the solution isotonic
✔✔what does HCL do to the anesthetic solutions? - ✔✔lower the pH for the addition of
epinephrine
✔✔what does epinephrine do the the anesthetic solutions? - ✔✔reduce absorption
rates at site of injection (increase duration/reduce blood levels - toxicity)
✔✔what do bisulfites do to the anesthetic solutions? - ✔✔reduce the oxidation of the
epinephrine (longer shelf-life)
✔✔what does methylparaben do to the anesthetic solutions? - ✔✔agent used for its
antibacterial action that is no longer contained in dental cartridges, only in multiple dose
vials
✔✔what are all of the effects that result when epinephrine is added to a solution? -
✔✔increased heart rate, increased systolic pressure, lowers diastolic pressure
✔✔what is the MCD (maximum cardiac dose) of epinephrine? - ✔✔0.04 mg (40ug)
✔✔what are the available options for lidocaine? - ✔✔2% either with 1:100,000 or
1:50,000 epi
