Local Anesthetics

Question 1

Benzocaine

Answer 1

Class: Ester type local anesthetic
Apps: short acting (20min), topical OTC pain reliever. Wide variety of uses: gag reflex suppression, mucous membrane anesthesia, anorectal disorders.
Mech: Block voltage-dependent Na+ channels.
Effects: allergic rxn b/c of PABA metabolite. methemoglobinemia

Question 2

Cocaine

Answer 2

Class: Ester type local anesthetic.
Apps: topical anesthesia, vasoconstriction for surgery of nose/throat
Mech: Block voltage dependent Na+ channels. Produces vasoconstriction (blocks NE uptake)
Effects: few, but seldom used in practice now

Question 3

Lidocaine

Answer 3

Class: Amide type local anesthetic
Apps: all types of local anesthesia requiring moderate duration (1-2h)
Mech: Block voltage-dependent Na+ channels.
Effects: uncommon. systemic absorption= nausea, drowsiness, mood changes, ringing in ears, dizziness, vision changes, tremors, numbness, headache

Question 4

Bupivacaine (Marcain)

Answer 4

Class: Amide type local anesthetic
Apps: local or regional anesthesia or analgesia for surgery, oral surgery. Therapeutic & diagnostic procedures, obstetrical procedures. Longer duration (6-8h) than lidocaine.
Mech: Block voltage-dependent Na+ channels.
Effects: can be cardiotoxic if administered incorrectly.

Question 5

Ropivacaine

Answer 5

Class: Amide local anesthetic.
Apps: Long acting, less cardiotoxic than Bupivacaine. For epidural, intra-articular, nerve block, infiltration anesthesia, post-op and labor pain. Less potent than bupivacaine.
Mech: Block voltage-dependent Na+ channels

Question 6

EMLA

Answer 6

Class: Topical Anesthetic
Apps: anesthetize normal, intact skin prioir to painful procedures.
Mech: Eutectic Mixture of Local Anesthetics cream contains lidocaine and prilocaine (Eutectic = 2 solids that remain liquid at room temperature)
Effects: contraindicated in patients w/ Hx of sensitivity to amide local anesthetics. Erythema or edema at site of treatment.