Local Anesthetics
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Questions and Answers

What physiochemical property of local anesthetics is described as the most important by Barash?

  • Vasoactive properties
  • Protein binding
  • Lipid solubility (correct)
  • pKa
  • How does the percentage of a local anesthetic in its neutral, non-protonated form relate to its pKa value?

  • No relationship
  • Exponential relationship
  • Directly proportional
  • Inversely proportional (correct)
  • Which characteristic of a local anesthetic molecule would lead to rapid entry into the lipid bilayer but potential sequestration?

  • Profound lipophilicity (correct)
  • High pKa
  • Low protein binding
  • Low lipid solubility
  • What property is associated with the rapid penetration of the lipid membrane by a local anesthetic?

    <p>Low pKa</p> Signup and view all the answers

    How does increased lipid solubility affect the onset of action of a local anesthetic?

    <p>Delays onset of action</p> Signup and view all the answers

    What factor is primarily responsible for increasing the duration of action of a local anesthetic?

    <p>Increased lipid solubility</p> Signup and view all the answers

    Which type of nerve fibers would be affected first with differential blockade?

    <p>Aδ sensory</p> Signup and view all the answers

    Which factor has the GREATEST influence on the amount of local anesthetic in the systemic circulation?

    <p>Site of injection</p> Signup and view all the answers

    Which local anesthetic has the SLOWEST rate of metabolism by hepatic enzymes?

    <p>Bupivacaine</p> Signup and view all the answers

    What is the relationship between protein binding and plasma concentration of local anesthetics?

    <p>Protein binding is inversely proportional to plasma concentration</p> Signup and view all the answers

    Which local anesthetic has the FASTEST rate of metabolism by plasma cholinesterase?

    <p>Chloroprocaine</p> Signup and view all the answers

    Which property of local anesthetics is considered the most important physiochemical property according to the text?

    <p>Lipid solubility</p> Signup and view all the answers

    What effect does increased protein binding have on the duration of action of local anesthetics?

    <p>Increased duration of action</p> Signup and view all the answers

    In relation to onset speed, what is the impact of increasing the dose/concentration of local anesthetics?

    <p>Speeds up the onset speed</p> Signup and view all the answers

    Which local anesthetic is highlighted as an exception due to its vasoconstrictive properties?

    <p>Cocaine</p> Signup and view all the answers

    How does increasing the lipophilicity of a local anesthetic impact the time to release the drug from lipid depots?

    <p>Increases the time</p> Signup and view all the answers

    Which factor most reliably correlates with the pKa of a local anesthetic according to the text?

    <p>Onset speed</p> Signup and view all the answers

    Which pharmacologic property correlates with a decrease in drug duration?

    <p>Decreased lipid solubility</p> Signup and view all the answers

    What effect does increased myelination have on nerve conduction?

    <p>Increases conduction speed</p> Signup and view all the answers

    What is the mechanism behind disrupting impulse conduction by local anesthetics?

    <p>Preventing sodium influx</p> Signup and view all the answers

    In Tonic Inhibition, slower firing fibers are less susceptible to blockade due to what characteristic?

    <p>Increased action potentials per unit time</p> Signup and view all the answers

    Which nerve type is MOST susceptible to blockade by local anesthetics?

    <p>C sensory fibers</p> Signup and view all the answers

    What condition increases the action potential frequency, making fibers more susceptible to blockade?

    <p>Tissue injury</p> Signup and view all the answers

    What is the clinical sequence of nerve blockade when increasing local anesthetic concentrations?

    <p>Aα motor first, B preganglionic sympathetic last.</p> Signup and view all the answers

    Which fiber type is considered least susceptible to blockade by local anesthetics?

    <p>C sensory fibers.</p> Signup and view all the answers

    What factor can prolong lidocaine metabolism and elimination the most?

    <p>Renal dysfunction</p> Signup and view all the answers

    Which local anesthetic has a chemistry that can potentially produce methemoglobinemia at high doses?

    <p>Benzoicaine</p> Signup and view all the answers

    Historically, which local anesthetic was primarily used in spinal anesthesia but is now rare outside dental applications?

    <p>Procaine</p> Signup and view all the answers

    Which local anesthetic is mainly used topically in ophthalmology and provides a profound motor and sensory block?

    <p>Tetracaine</p> Signup and view all the answers

    What is the primary purpose of adding vasoconstrictors to local anesthetics?

    <p>To decrease the rate of vascular absorption</p> Signup and view all the answers

    Which local anesthetic is known for its intense vasoconstriction properties and is primarily used in nasopharyngeal procedures?

    <p>Cocaine</p> Signup and view all the answers

    Where are vasoconstrictors commonly added to local anesthetics?

    <p>To decrease systemic absorption</p> Signup and view all the answers

    Which local anesthetic has a slow onset and short duration, and was historically used mainly in spinal anesthesia?

    <p>Procaine</p> Signup and view all the answers

    Chloroprocaine (Nesacaine) is primarily used for epidural analgesia conversion to anesthesia.

    <p>True</p> Signup and view all the answers

    Benzoicaine (Hurricaine) has a duration of 60-90 minutes.

    <p>False</p> Signup and view all the answers

    Mepivacaine (Carbocaine) has a slower onset compared to lidocaine.

    <p>False</p> Signup and view all the answers

    Adding vasoconstrictors to local anesthetics decreases the density of blockade.

    <p>False</p> Signup and view all the answers

    Local anesthetics like lidocaine are primarily used for chronic neuropathic pain management.

    <p>True</p> Signup and view all the answers

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