Exam 2 Locals Flashcards
Local Anesthetics are made of?
Weak bases
Local Anesthetics types?
Esters
Amides
Ester anesthetics duration?
Toxicity?
Short
↑ system toxicity
Local Anesthetics route in body?
Ionized when injected ->
Non-ionized to cross membrane ->
Re-ionized inside cell ->
Bind Na+ channels on inner membrane ->
Inflammation affects locals how?
↑ acid environment ->
↑ ionized form of local =
less effective
Bicarbonate affects locals how?
Basic environment ->
↑ non-ionized form of locals =
more effective
Local Anesthetics mechanism of action?
Block Na+ channels -> ↑ excitation/opening thresholds, ↓ Na+ current into cell slowing conduction, ↓ rate of AP = inhibit neuron firing
Locals have high affinity for what channels?
Low affinity for what channels?
Active and inactive Na+ channels
Resting Na+ channels
High Ca2+ affects locals how?
Hyperpol’s membrane potential ->
More channels in resting state ->
↓ locals effectiveness
High K+ affects locals how?
Depol’s membrane potential ->
More channels in inactive state ->
↑ locals effectiveness
Potency of locals dependent on what?
Measured in relationship to what?
Lipid solubility and duration
Procaine (low solubility, short duration)
Duration of action dependent on what?
Toxicity is dependent on what?
time locals stay at site
t1/2
Distribution of Locals: Phases
α phase?
β phase?
α = rapid diffusion to highly perfused areas
β = delayed diff to less perfused areas
Esters metabolized by?
Rapidly by butyrylcholinesterase in plasma
Amides metabolized by?
Liver CYP450s
