Local Anesthetics

Question 0

Tetracaine

Answer 0

Local anesthetic - ester
slow onset/long duration,16x more potent/toxic than procaine
ophtalmo sx (retrobulbar) & spinal anesthesia (+dextrose-hyperbaric)

Question 1

Procaine

Answer 1

Local anesthetic - ester
No topical action, used for infiltration anest, dx nerve blocks
Short acting, met: PABA (allergies, inactivates sulfonamides), low tox, no local irritation

Question 2

Benzocaine

Answer 2

Local anesthetic - ester
Lipophilic, pKa 3.5 always non-ionized: topical only!
Risk of methemoglobinemia

Question 3

Cocaine

Answer 3

Local anesthetic - ester, 2ary mech (1ary inc in DA-euphoria)
topical-mucous membranes (dental)
Risk: HTN, CV, thyrotoxicosis

Question 4

Lidocaine

Answer 4

Local anesthetic - amide, intermed action, also antiarrhythmic
Infiltration blocks, epidural anesthesia
NOT for spinal blocks (risk of TNS)
+/-epi

Question 5

Prilocaine

Answer 5

Local anesthetic - amide, intermed duration
highest rate of clearance (careful w/ hep failure)
Methemoglobinemia risk (give methylene blue)
CI: CV or resp disease. Dentistry use

Question 6

Bupivacaine

Answer 6

Local anesthetic - amide, long duration
Post-op analgesia, spinal, infiltration, epidural- pref for childbirth
Cardiac tox- inc binding to resting Ca2+ ch, slow dissociation.
More potent sensory than motor block

Question 7

Mepivacaine

Answer 7

Local anesthetic - amide, intermediate

peripheral block, not for topical, not for labor (too short)

Question 8

Ropivacaine

Answer 8

Local anesthetic - amide, long acting
S-enantiomer of bupivacaine- less lipid soluble, faster clearance, less cardiac tox. Vasoconstriction!
Peripheral, epidural blocks

Question 9

Etidocaine

Answer 9

Local anesthetic - amide, long duration

inverse differential block: motor block before sensory

Question 10

Articaine

Answer 10

Local anesthetic - amide + add’l ester grp (less T1/2 & tox)
Dental med-large tx window, can inject more if needed later
Adverse: persistent paresthesias (rare)

Question 11

Dibucaine

Answer 11

Local anesthetic - amide, topical only

Dibucaine number test: measures butyrylcholinesterase activity (<80-deficient)