local anesthetic Flashcards
List the local anesthetic: Esters
- Procaine (Novocain®)
- Tetracaine (Pontocaine®)
- Benzocaine (Americaine®)
- Cocaine
what drug class is Lidocaine (Xylocaine®) in
local anesthetics: amides
what drug class is Prilocaine (Citanest®) in
local anesthetics: amides
what drug class is Bupivacaine (Marcaine®) in
local anesthetics: amides
what drug class is Mepivacaine (Carbocaine®) in
local anesthetics: amides
what drug class is Ropivacaine (Naropin®) in
local anesthetics: amides
what drug class is Etidocaine (Duranest®) in
local anesthetics: amides
what drug class is Articaine (Septocaine®) in
local anesthetics: amides
what drug class is Dibucaine (Nupercainal®) in
local anesthetics: amides
what drug class is Baclofen (Lioresal®) in
- GABA-mimetic
- muscle relaxant
what drug class is Diazepam (Valium®) in
- Benzodiazepine
list the 4 spinal cord or brain stem sedatives
- Cyclobenzaprine (Flexeril®)
- Carisoprodol (Soma®)
- Metaxalone (Skelaxin®)
- Methocarbamol (Robaxin®)
local anesthetics are broken down into what 2 groups
- esters
- amides
do esters or amides have shorter duration of action? which has increased systemic toxicity?
- Esters have shorter duration of action
- Esters have increased systemic toxicity
local anesthetics are acids or bases?
- weak bases
- pKa = 7.5-9
What form does the local anesthetic need to be in to cross the cell membrane? what form binds to Na+ channel
- non-ionized (LA + H+)
- ionized (LAH+)
the closer the pKa is the physiological pH (7.4) the higher the concentration of the local anesthetic in what form? what benefit does this have
- non-ionized form
- membrane transport increases -> faster onset of action
- ex: lidocaine (pKa 7.8) has a faster onset than bupivacaine (pKa 8.1)
- membrane transport increases -> faster onset of action
what local anesthetic drug is an exception to the rule and even at a pKa of 3.5 is always in the non-ionized form ? route of administration?
Benzocaine
- topical application only
how does bicarbonate affect LA transport across cell membrane
- makes pH more basic and may increase non-ionized drug concentrations and thus, the degree of LA transport
MOA of local anesthestics
-
block Na+ channels and inhibit neuronal firing and the propagation of action potentials
- When progressively increasing concentrations of a local anesthetic are applied to a nerve fiber, the threshold for excitation increases, impulse conduction slows, the rate of rise of the action potential declines, and finally, the ability to generate an action potential is completely abolished.
LA have high affinity for Na channels in what state
- high affinity for channels in the activated (open state) and inactivated state and lower affinity for channels in the resting (closed) state
- drug is more marked in rapidly firing axons than in resting fibers.
what effect does elevated calcium have of the MOA of local anesthetics
- increase membrane potential; more channels are in resting state and the effect of LAs is diminished.
what effect does elevated potassium have of the MOA of local anesthetics
- depolarize the membrane; more channels in inactivated state and the effect is enhanced
duration of action of local anesthetics is dependent on
spent at the site of action
List local anesthetics with a short duration of action
- Procaine
List local anesthetics with a medium duration of action
- cocaine
- Mepivacaine
- Lidocaine
List local anesthetics with a long duration of action
- Tetracaine
- Bupivicaine
- Ropivicaine
toxic effects of LA are dependent on
half-life
how does epinephrine affect absorption of local anesthetic
- epinephrine -> vasoconstriction
- decreases diffusion of drug
- prolongs duration of action
- decreases systemic absorption and decreases risk of systemic toxicity
Where are Amides LA metabolized
- Liver by CYP450
- toxicity is more likely in pts with hepatic disease or reduced hepatic blood flow
Where are esters LA metabolized
- rapidly metabolized by butyrylcholinesterases in the plasma