Local Anesthetics Flashcards
(25 cards)
General MOA of local anesthetics
inhibit voltage gated Na channels (VGSD) ion flux – bocks conduction of AP in nociceptive nerve fibers achieving rapid analgesia w/o sedation
VGSC structure
pore-forming alpha subunit, 4 beta subunits Depolarization: alpha residues shift to open Repolarize: alpha residues go back Inactive:
Nociceptive fiber quality
less myelination, more sensitive to sodium channel inhibition (relative selectivity)
- LA’s are NOT totally selective for nociceptive fibers.
TRPV1 receptor
selectively expressed in nociceptive fibers; when administer capsaicin (TRPV1 ligand) with LA, selectively blocks pain receptors.
Benzocaine
Ester
Procaine
Ester
Tetracaine
Ester
Lidocaine
Amide
1-3 hours
Bupivacaine
Amide
DOA - 2-5 hours
Mepivacaine
Amide
DOA - 1.5-3 hours
Prilocaine
Amide
Ropivacaine
Amide
Dibucaine
Amide
Esters
- Structure related to cocaine
- Short half life (
Amides
- Longer lasting effect
- Metabolized by Cyp 450
Na Channel Blockers (neurotoxins)
Tetrodotoxin, saxitotoxin
LA side effect (CNS)
Depress neuronal activity in brain and spinal cord
seizures, sedation, resp failure, psychosis, depression
LA Side effects (CV)
- decreased mycoardial excitability
- arrhythmia, cardiac failure
- vasodilation
LA side effects (skeletal musc)
at high concentration: reduced NMJ transmission
LA Side effects (Allergy)
skin or lung
LA Side Effect Categories
CNS, CV, skeletal muscle, allergies
Infiltration anesthesia field block: Combination with epinephrine does what?
prolongs effect and reduces systemic spread
Nerve block
lidocaine, mepivacaine, bupivacaine
Intravenous regional anesthesia
in an exsanguinated area, and distal to a
tourniquet to block systemic distribution
