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22 Cards in this Set

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ester vs amide local anesthetics. significance? examples?
-esters are hydrolized rapidly by plasma esterases, and by liver esterases
-amides are hydrolized only by liver exzymes
-esters: cocaine, procaine, benzocaine
-amides: lidocaine, bupivacaine
what is the typical pKa of a local anesthetic w/ an amine?
8-9
where is the target site for local anesthetics? how does this relate to the ionic state of the drug? how does neuronal susceptibility vary accordingly?
target site is on the inner part of the voltage gated Na channel, thus uncharged drug must diffuse the cell membrane, and then charged form is active at the site.
-active neurons are more susceptible to great inhibition because open channels bind drug better than closed channels
which local anesthetic is known to be cardiotoxic?
bupivacaine
what nerve types are most sensitive to local anesthetics?
small, unmyelinated nerves, eg pain fibers
why are local anesthetics ineffective when administered directly to an infected site?
areas of infection have low pH. this leads to more anesthetic in the protonated (ionized) form, which hinders diffusion into cell
why are vasoconstrictors sometiems applied w/ local anesthetics?
these reduce blood flow to the region which:
1 - delay absorption into blood, thus prolong anesthetic effects at site
2 - delay absorption into blood, and thus to other organs, reducing systemic side effects
cocaine is an ester anesthetic. what other actions does it have?
it has its own sympathetomimetic actions, by blocking catecholamine reuptake, which
1. lead to tachycardia, HTN
2. CNS actions - delusion/hallucinations/paranoia
what is the MOA of inhaled anesthetics?
no certain target is identified, but they potentiate effects at GABA-A-Rs.
however, N2O works mainly at NMDA-Glutamate-Rs
what is MAC? how does MAC relate to potency? How does MAC relate to speed of onset?
MAC = mean alveolar concentration that makes 50% of subjects senseless to pain.
-lower MAC = potency.
-MAC does not relate to the speed of onset!
-however, the more potent have slower onsets.
how does the blood:gas partition coefficient relate to inhaled anesthetics
low blood:gas PC means a more rapid onset of action
what is the rate limiting step for getting an inhaled anesthetic into the brain tissue?
establishing tension in the blood, aka Vapor Pressure
what is one potential complication with halothane?
hepatitis, may lead to hepatic necrosis
a person on a halogenated inhaled anesthetic (halothane, sevuflurane, enflurane, isoflurane) gets hyperthermia. discuss
it is an autosomal dominant disorder, response to halogenated anesthetic + succinylcholine. treat with Dantrolene
which local anesthetic is known to be cardiotoxic?
bupivacaine
what nerve types are most sensitive to local anesthetics?
small, unmyelinated nerves, eg pain fibers
why are local anesthetics ineffective when administered directly to an infected site?
areas of infection have low pH. this leads to more anesthetic in the protonated (ionized) form, which hinders diffusion into cell
why are vasoconstrictors sometimes applied w/ local anesthetics?
these reduce blood flow to the region which:
1 - delay absorption into blood, thus prolong anesthetic effects at site
2 - delay absorption into blood, and thus to other organs, reducing systemic side effects
cocaine is an ester anesthetic. what other actions does it have?
it has its own sympathetomimetic actions, by blocking catecholamine reuptake, which
1. lead to tachycardia, HTN
2. CNS actions - delusion/hallucinations/paranoia
how does CO relate to induction time for inhaled anesthetics? more notable for soluble or insolubles? describe the feedback loop
a reduced CO will lead to a more rapid induction
-more notable for soluble drugs, eg halothane
-positive feedback, as the drugs will depress CO
how does ventilation relate to induction time for inhaled anesthetics? more notable for soluble or insolubles? describe the feedback loop
an increased ventilation will lead to a more rapid induction
-more notable for soluble drugs, eg halothane
-negative feedback, as the drugs will depress ventilation via CNS respiratory centers
factors decrease or increase MAC?
hypotension
hypothermia
narcotics
young age
sedatives
alcohol acute
alcoholism
other anesthetics
hypotension - lower
hypothermia - lower
narcotics - lower
young age - increase
sedatives - lower
alcohol - lower
alcoholism - increase
other anesthetics - lower