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22 Cards in this Set
- Front
- Back
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ester vs amide local anesthetics. significance? examples?
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-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 |
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what is the typical pKa of a local anesthetic w/ an amine?
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8-9
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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?
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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 |
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which local anesthetic is known to be cardiotoxic?
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bupivacaine
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what nerve types are most sensitive to local anesthetics?
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small, unmyelinated nerves, eg pain fibers
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why are local anesthetics ineffective when administered directly to an infected site?
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areas of infection have low pH. this leads to more anesthetic in the protonated (ionized) form, which hinders diffusion into cell
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why are vasoconstrictors sometiems applied w/ local anesthetics?
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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 |
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cocaine is an ester anesthetic. what other actions does it have?
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it has its own sympathetomimetic actions, by blocking catecholamine reuptake, which
1. lead to tachycardia, HTN 2. CNS actions - delusion/hallucinations/paranoia |
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what is the MOA of inhaled anesthetics?
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no certain target is identified, but they potentiate effects at GABA-A-Rs.
however, N2O works mainly at NMDA-Glutamate-Rs |
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what is MAC? how does MAC relate to potency? How does MAC relate to speed of onset?
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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. |
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how does the blood:gas partition coefficient relate to inhaled anesthetics
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low blood:gas PC means a more rapid onset of action
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what is the rate limiting step for getting an inhaled anesthetic into the brain tissue?
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establishing tension in the blood, aka Vapor Pressure
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what is one potential complication with halothane?
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hepatitis, may lead to hepatic necrosis
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a person on a halogenated inhaled anesthetic (halothane, sevuflurane, enflurane, isoflurane) gets hyperthermia. discuss
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it is an autosomal dominant disorder, response to halogenated anesthetic + succinylcholine. treat with Dantrolene
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which local anesthetic is known to be cardiotoxic?
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bupivacaine
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what nerve types are most sensitive to local anesthetics?
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small, unmyelinated nerves, eg pain fibers
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why are local anesthetics ineffective when administered directly to an infected site?
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areas of infection have low pH. this leads to more anesthetic in the protonated (ionized) form, which hinders diffusion into cell
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why are vasoconstrictors sometimes applied w/ local anesthetics?
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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 |
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cocaine is an ester anesthetic. what other actions does it have?
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it has its own sympathetomimetic actions, by blocking catecholamine reuptake, which
1. lead to tachycardia, HTN 2. CNS actions - delusion/hallucinations/paranoia |
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how does CO relate to induction time for inhaled anesthetics? more notable for soluble or insolubles? describe the feedback loop
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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 |
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how does ventilation relate to induction time for inhaled anesthetics? more notable for soluble or insolubles? describe the feedback loop
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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 |
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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 |
