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11 Cards in this Set
- Front
- Back
Describe the mechanism of action of the local anesthetic drugs.
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they primarily act on a site in the sodium ion channel, decreasing or preventing transient Na increase that causes depolarization
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Describe how hydrophobicity affects the structure- activity relationship of a local anesthetic.
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hydrophobicity increases the potency and duration of action, by increasing the binding with the sodium channel receptor
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Infected tissue often has a low pH. What affect pH have on the onset and duration of action of an injected local anesthetic? What
affect would the co-administration of sodium bicarbonate have on the duration of onset and action in normal tissue? |
lower pH slows uptake and lengthens duration of action, bicarbonate has the opposite effect
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List the order of nerve fiber block and recovery following perineural local anesthetic administration.
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Small nonmyelinated nerve fibers are the first to be blocked (sympathetic fibers) and the last to recover.
Larger myelinated fibers (motor neurons) are the last to be blocked and the first to recover. When myelinated and nonmyelinated nerve fiber diameters are equal the myelinated fibers will be blocked first. The order of loss of nerve function (from first to last) is pain, cold, warmth, touch, deep pressure, and finally motor function |
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Describe how co-administration of epinephrine affects the duration of action and toxicity of lidocaine.
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due to vasoconstriction epinephrine prolongs the action of lidocaine, and due to the slowed uptake prevents toxicity
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What are the CNS effects of local anesthetics?
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General CNS signs are excitation
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Compare and contrast the cardiovascular effects of lidocaine and bupivacaine.
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Bupivicaine causes cardiogenic problems at lower doses than CNS excitation, Lidocaine shows CNS signs at lower doses than Cardiac signs
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Contrast the metabolic fate of ester and amide local anesthetics.
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Ester drugs usually do not use hepatic metabolism while amides do
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Draw or be able to identify a generic structure of an amide and ester local anesthetic
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??
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Contrast cocaine and lidocaine with respect to affects on vasomotor tone. What is the mechanism of this difference
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Cocaine causes direct vasoconstriction due to its effect on catecholamine uptake in noradrenergic nerve terminals
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Be able to categorize the drugs listed in the notes as either esters or amides.
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Esters - cocaine, procaine, tetracaine
Amines - lidocaine, bupivicaine, mepivicaine |