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18 Cards in this Set
- Front
- Back
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what is the MOA of local anesthetcs?
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Block voltage-gated sodium channels
bind to specific receptors at the INTRACELLULAR end of the voltage gated sodium channel prevent axonal conduction by a functional blockade |
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what is the relationship btw pKa and rate of onset for local anesthetics?
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lower the pKa the faster the onset of action
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how can you keep the ester and amide local anesthetics apart?
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AMIDE LINKAGE (2 EYES!!)
LIDOCAINE lidocaine (Xylocaine) mepivacaine (Carbocaine) bupivacaine (Marcaine) etidocaine (Duranest) ropivacaine (Naropin) vs ESTERs PROCAINE procaine (Novocaine) tetracaine (Pontocaine) benzocaine cocaine |
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which type of local anesthetic are more likely to cause allergic response
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Esters are metabolized to common metabolite PABA
allergic remember esters only have 1 eye |
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which type of local anesthetic are more likely to systemic response
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amides
Hydrolyzed by liver microsomal enzymes (P450) Longer acting & more systemic toxicity than esters Caution with severely compromised hepatic function |
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what terminates the action of Local Anesthetics
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Systemic absorption (out of tissues) terminates local action (Not local metabolism)
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what are the good effects of vasoconstictors when used w/ Local Anesthetics?
bad? |
good:
Decrease rate of systemic absorption and decrease systemic toxicity Increase local drug concentration and increase neuronal uptake of LA Increase local duration of action (e.g. lidocaine’s duration my increase two fold with epi) Bad: DON’T use in areas of toes, fingers, ear lobes, penis (ischemia) May produce tissue necrosis May produce systemic toxicity (cardiovasc) |
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esters do not normally cause systemic effects...how could they though?
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Prolonged effects seen with genetically determined deficiency or altered esterase (cholinesterase inhibitors)
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7. indicate which system is most sensitive to systemic effect of local anesthetics and which system is second most sensitive
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1. CNS
First an apparent CNS stimulation (convulsions most serious) Followed by CNS depression (death due to respir depression) Premonitory signs include: ringing in ears, metalic taste, numbness around lips 2. CVS HYPOTENSION: Arteriolar dilation is a result of: Direct effect (procaine and lidocaine have most effect) Block of postganglionic sympathetic fiber function CNS depression Avoid by adding vasoconstrictor to prep Note: cocaine is exception: produces vasoconstriction, blocks NE reuptake ARRHYTHMIAS: direct effect (More resistant than CNS) Decrease cardioexcitability and contractility Decreased conduction rate Increased refractory rate (bupivicaine) Note: cocaine is exception......it stimulates heart ALL can cause arrhythmias if conc. is high enough |
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What drug is likely responsible for CV arrhythmia??
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bupivicaine
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8. indicate in what ways cocaine differs from most local anesthetics with regards to CNS and vascular effects.
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CNS: euphoria
CVS: cocaine is exception......it stimulates heart and: produces vasoconstriction, blocks NE reuptake |
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what is cauda equina syndrome? what is responsible for this?
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transient neurological symptoms after spinal anesthesia
LA can cause concentration-dependent nerve damage to central and peripheral NS |
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which LA is limited to surface or topical anesthesia only?
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Benzocaine
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this drug is
topical, infiltration and spinal anesthesia Frequently used for topical ophthalomogical anesthesia slow onset and more prolonged effect than procaine (longest duration of the esters) ~10X more toxic and more potent than procaine |
Tetracaine
ester |
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most widely used local anesthetic?
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LIDOCAINE
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what local anesthetic drug is most likely to cause sedation?
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LIDOCAINE
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what local anesthetic drug cannot be used in obstetrical anesthesia
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mepivicaine
More toxic to neonates so not used in obstetrical anesthesia (fetus poorly metabolizes mepivicaine) |
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which LA is most likely to produce vasoconstrictor effects
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• cocaine
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