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16 Cards in this Set
- Front
- Back
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Cocaine, benzocaine, procaine (novocaine), & tetracaine are examples of what class of drugs (specific)?
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Local anesthetics- ESTERS
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Lidocaine & bupivacaine are examples of what class of drugs (specific)?
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local anesthetics- AMIDES
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Describe the chemical traits of local anesthetics (lipophilicity, pKa, ester, protein-binding).
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Lipo: directly related to POTENCY
pkA: INdirectly related to speed of onset Ester: hypersensitivity protein-binding: directly related to DURATION |
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Which is the least/most potent local anesthetic?
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Least (least lipid soluble): procaine (ester)
Most: tetracaine |
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In general, to the amides or esters have a faster speed of onset? (assume pH 7.4)
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AMIDES are faster (lower pKa, closer to 7.4)
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Where is the site of action of local anesthetics?
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interior of nerve membrane
interior of Na+ channel (access depends on rate & duration of channel opening) |
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When can the local anesthetics reach and bind to voltage gated Na+ channels? (resting, depol, repol)
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Resting potential: inactivation gate open (can bind via hydrophilic route)
activation gate is closed (no Na+ entry) Depolarized: inactivation gate open (can bind) Repolarization: inactivation gate closed --> can't bind! |
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At an injection site of low pH (e.g. abscess), would a local anesthetic cross the neuronal membrane? Why or Why not?
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at low pH, even a weak base (lidocaien) can be 99% ionized and will not cross the membrane (BH+)
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How are local anesthetics metabolized?
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Esters: Rapid (1-5 min) -- via plasma cholinesterase
amides: slow (1-4 hrs) via hepatic CYP 450 |
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How can you minimize the systemic absorption of local anesthetics?
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Some (procaine, lidocaine) dilate vessels which hastens re-distribution and shortens duration of action
Vasoconstrictors: dec. rate of vascular absorption Epinephrine is the best choice! |
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1. What local anesthetic delivery METHOD is used in minor surgeries?
2. Nose/mouth/bronchial tree/cornea/urinary tract? 3. surgery/dentistry/analgesia? |
1. INFILTRATION (inject into tissues)
2. surface (topical) - lidocaine, tetracaine 3. Nerve block - inject into region of nerve plexus/trunk |
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In what clinical setting is cocaine used. What is its main effect?
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surface or topical anesthesia (CORNEAL)
it is a vasoCONSTRICTOR |
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What local anesthetic is commonly used for spinal anesthesia?
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procaine (novocaine) - inflitration
use epinephrine to prolong effect |
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What drug is the most widely used local anesthetic that is effective by all routes of administration?
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Lidocaine -- fast onset, long lasting
sedation > than other local anesthetics |
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What local anesthetic can be given topically or through infiltration or spinal anesthesia, has a slow onset but prolonged effect? It is also very toxic/potent.
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Tetracaine
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What local anesthetic is useful during labor but is more cardiotoxic than other drugs?
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Bupivacaine
sensory analgesia w/ minimal motor block |
