Local Anesthetics (KEY POINTS) Flashcards
How do you tell the difference btwn the names of esters vs amides?
Both have “caine”
But esters have only 1 letter i & amides have 2 letter i’s.
Ex. Procaine (ester) vs lidocaine (amide)
Which ester has a short duration of action /low potency?
Procaine
Which ester and amides have a long duration of action / high potency?
Tetracaine (ester)
Bupivacaine, ropivacaine (amides)
What is local anesthesia?
sensory transmission from a local area to the CNS is blocked
What are 4 MOA of local anesthetics?
- Block Na channels
- Reduce influx of Na
- Prevent depolarization
- Block conduction of AP
What are the roles of the 1. nonionized (uncharged) & 2. ionized (charged) forms of the drug?
- Reach receptor site
2. Cause the effect
Local anesthetics: the onset of action may be accelerated by addition of…
Sodium bicarb
What prolongs duration of shorter acting local anesthetics?
Administration of α-agonist sympathomimetic vasoconstrictor (epinephrine)
How are ester vs amide local anesthetics metabolized?
Ester = by plasma cholinesterase (rapid)
Amide = by the liver
Organize the esters from rapid to slow metabolism
Procaine > cocaine > tetracaine
Organize the amides from rapid to slow metabolism
Lidocaine, prilocaine > bupivacaine, ropivacaine
What fibers are blocked more easily?
Smaller, myelinated
What are characteristics of central neuraxial techniques (spinal or epidural)?
Motor paralysis may impair resp. activity
Autonomic nerve blockade may promote hypotension
How can motor paralysis be a disadvantage during labor?
May limit ability to bear down
How can motor paralysis be a disadvantage post-op?
hamper ability to ambulate
interference w/ bladder fxn
