Week 2 Flashcards
New FDA law requires LA carpule labeling to say?
1.7 mL
Name 2 buffering agents that can be in the carpule
sodium hydroxide and sodium chloride
The vasoconstrictor present in the carpule
epi or levonordefrin
This vasoconstrictor preservative helps decrease the solution pH to delay the onset of the LA
sodium bisulfite
If a pt reported that they had an allergic rxn to a LA before 1984, then what were they probably allergic to?
parabens
Esters are metabolized in the ______ while amides are metabolized in the _________
blood; liver
T/F: Allergic rxns are rare with esters.
False bruh they’re hella common
ALL injectables LAs are?
amides
Describe the chemical structure of LAs
1) lipophilic aromatic ring
2) intermediate linkage
3) hydrophilic terminal amine
Which part of the chemical structure of LAs determines if it’s an ester/amide?
the intermediate linkage
Once the LA has gained a ________ ion, it’s now in it’s ___________ form
H+; active
L.A. molecules in the cartridge include anions and cations. How do they differ with their onset?
more anions: low pKa, more base, fast diffusion, rapid onset
more cations: high pka, less base, slow diffusion, slow onset
Infected tissues are acidic. What happens if you inject LA into this acidic tissue?
since the LA is also acidic, then there will be less molecules that cross the membrane = INADEQUATE ANESTHESIA
L.A. must penetrate _______mm of myelinated nerve length (3-4 nodes of Ranvier) to block a nerve impulse
↑ — of L.A. is required for large nerves (inferior alveolar n.)
8-10mm
↑___________ of L.A. is required for large nerves (inferior alveolar n.)
volume
Describe the onset if there is a high concentration of the LA and it has a low pKa
rapid onset
What happens to the dosage if the lipid solubility decreases?
have to increase the dose to enhance diffusion of drug through the nerve
What happens to the duration of the LA if there is increased protein binding?
increased duration
T/F: LAs are vasodilators
true
Pharmacokinetics of LAs include…. (fat list)
1) onset of action
2) induction
3) recovery from block
4) reinjection
5) duration / potency
6) distribution
7) absorption
8) biotransformation (metabolism)
9) excretion
10) systemic effects
period from LA deposit to blocked impulse conduction
onset of action
the primary factor of onset of action of a LA
pKa!!!
low pKa = rapid onset
secondary factor of onset of action of LA
site!
small diameter nerves have rapid onset
primary factor of induction of LAs
initial concentration
increased conc = rapid onset
