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17 Cards in this Set
- Front
- Back
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What are Local Anethetics two major groups?
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Ester and amides
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How do ester-type and amide-type agents differ?
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1) Different method of inactivation
2) Different promotion of allergic response. |
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Local Anesthetics Mechanism of Action
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Stop axonal conduction by blocking Na channels in the axonal membrane
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Selectivity of Local Anesthetic Effects:Are they selective or nonselective? Do they block conduction in motor neurons?
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Local anesthetics are nonselective- block action potential in all neurons.
Yes- blocks sensory and motor (funny face leaving dentist) |
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Onset is determined by molecule size: What 3 properties determine axon membrane penetration?
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Molecular size
lipid solubility degree of ionization at tissue pH |
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Cross slow or fast?
small, high lipid solubility, & Low ionization |
Cross membrane fast
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Cross slow or fast?
Large, low lipid solubility, and high ionization |
Cross membrane slow
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What med is sometimes adm with Local anesthetics?
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Vasoconstrictors
Example- Epinephrine |
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Why are vasoconstrictors adm with Local Anesthetics?
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Dec. local bld flow and thereby delays systemic absorption
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What are the benefits of delaying absorption by vasoconstrictors?
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Prolongs anesthesia and reduces risk of toxicity
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Where are Ester-type anesthetics metabolized? and by what?
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In the bld by enzymes called esterases.
occasionally causes allergic reaction |
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Where are amide-type anesthetic drugs metabolized?
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By enzymes in the Liver
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General adverse effects in local anesthetics.
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CNS depression-convulsions-tx-IV versed or diazapam, Cardiovascular problems-brady, heart block, cardiac arrest, dec BP,
Allergic reaction Prolong labor |
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CNS Adverse Effects of Cocaine
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euphoria, loquaciousness, reduced fatigue, and increased sociability and alertness, seizures
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Cardiac Adverse Effects of Cocaine
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Tachycardia, fatal dysrhythmias, hypertension
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Can Epi be adm with cocaine and Why?
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No because it causes increase risk for cardiovascular toxicity
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Local Anesthesia use
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Nerve Block- lidocaine, mepivacaine, (long-bupivacaine)
IV regional- lidocaine (no epi) Epidural-Lidocaine, bupivacanine Spinal- bupivacaine, lidocaine, or tetracaine |
