Local anesthetics

Question 1

Cocaine; benzocaine; procaine; tetracaine; chlorprocaine

Answer 1

• Ester anesthetic: binds reversibly to the intracellular portion of the voltage-gated sodium channel and inactivates it, and so blocks transmission of nociceptive nerve impulses
• Local anesthesia
• Side effects: Local: transient neurologic symptoms (basically, really bad pain), neuronal injury. Systemic (more common with long-acting local anesthetics): circumoral numbness, dizziness, tinnitis, blurred vision, CNS excitation (restlessness, agitation, seizures), followed by CNS depression (respiratory arrest, unconsciousness); hypotension; cardic toxicity with higher doses.
• Methemoglobinemia with benzocaine, allergic rxns
• Used less frequently than amides

Question 2

Lidocaine; mepivacaine; bupivacaine; ropivacaine

note the two i’s in each name

Answer 2

• Amide anesthetic: binds reversibly to the intracellular portion of the voltage-gated sodium channel and inactivates it, and so blocks transmission of nociceptive nerve impulses
• Local anesthesia
• Side effects: Local: transient neurologic symptoms (basically, really bad pain), neuronal injury. Systemic (more common with long-acting local anesthetics): circumoral numbness, dizziness, tinnitis, blurred vision, CNS excitation (restlessness, agitation, seizures), followed by CNS depression (respiratory arrest, unconsciousness); hypotension; cardic toxicity with higher doses.
• Bupivicaine has highest cardiac toxicity potential; ropivicaine less potent than others (so larger therapeutic index)