Local Anesthetics Flashcards
What are the two classes of local anesthetics?
amide and ester type
What is the approximate pK of LA?
8-9
Are LAs more ionized or less ionized at physiologic pH?
more ionized
Where do LA work?
intracellular side of VG Na+ channels
How do LA get across the cell membrane?
non-ionized form crosses
non-ionized form is ionized
ionized form is active on VG Na+ channels
What is the active form of LA?
ionized
What form of LA crosses the membrane?
non-ionized
LA work on NA channels at what stages:
- resting
- open
- inactivated
only open and inactivated
more potent on more active neurons
Side effect of LA with regards to circulation?
sm. muscle VG Na+ channels also blocked
–>vasodialation
==>faster clearing of drug
Why is epinephrine added to more LA preparations?
they cause vasoconstriction
Where are ester LA metabolized?
in plasma
pseudocholinesterase
Where are amide LA metabolized?
in liver
mixed oxidases
What type of LA is more common to produce a hypersensitivity reaction?
ester
What is a Bier block?
IV admin of LA with tourniquet
Ester is old and needs PT
procaine and
tetracaine are ester LA
