Neuroanatomy-Local Anesthetics

Question 1

Esters

Answer 1

(rapid metabolism) - Butyrlcholinesterase

Impacts:

• Cardiovascular System: (local anesthetics are sodium
  channel blockers). Cocaine: Sympathomimetic (makes these effects worse) - Cause direct suppression of the heart (absorbed excessively)
• Nervous System (same as CV, first GABA shutdowns -> local excitability and then over time excitatories are shutoff -> Coma)

Question 2

Amides

Answer 2

(slower metabolism) - Hepatic Microsomal System (lower metabolism)

Impacts:

• Cardiovascular System: (local anesthetics are sodium
  channel blockers) - Cause direct suppression of the heart (absorbed excessively).
• Nervous System (same as CV, first GABA shutdowns -> local excitability and then over time excitatories are shutoff -> Coma)

Question 3

Procaine (Novacaine)

Answer 3

Ester

-short half-life
-hypersensivity reactions
-injectable
-not surface

Question 4

Tetracaine

Answer 4

Ester

• Longer Duration of Action than Procaine (Novacaine)
• Topical and Injectable
• Ophthalmic

Question 5

Cocaine

Answer 5

Ester

-Not widely used
-Respiratory Tract Anesthetic
-CNS Side Effects
-CV Side Effects

Question 6

Benzocaine

Answer 6

Ester

(not absorbed that well) -Topical only

Question 7

Lidocaine

Answer 7

Amide

(most widely used local anesthetic agents)

• Longer Lasting than Esters
• Efficiently Absorbed from Mucous Membranes

-All Routes, except eyes

• Often given as an Epidural. Large amounts needed. (Subarachnoid Space in Lumbar Region). Can often cause CV Depression (Autonomic nerves impacted also).

Question 8

Bupivacaine

Answer 8

Amide

(also widely used)

• Long Lasting
• Injectable
• Not Effective on Surface

Question 9

Vasoconstrictor Action

Answer 9

A. Increase Duration by 50% (stays in area)

B. Reduced Toxicity (stays local)

C. Epi, Norepi, Phenylephrine, Vasopressin

D. Overdosage- Hypoxia (avoid extremities-fingers/toes/etc)

E. Cocaine- Natural Vasoconstrictor