01 - Local Anesthetics

Question 1

(Local Anesthetics)

(definition)

1. drugs that block what?
2. when applied to what part of the nervous system?
3. on what type of nerve fiber?
4. is there a loss of conciousness?
5. prototype?
6. what is common?

Answer 1

1. nerve conduction and generation of action potentials
2. any part
3. every type
4. no
5. procaine
6. lidocaine

Question 2

(Desirable Charactertistics of Local Anesthetics)

1. should not be irritating or produce permanent damage
2. should not be addictive
3. low systemic toxicity
4. rapid onset
5. duration - long enough for what is needed
6. should it be reversible?

Answer 2

6. yes

Question 3

(Structure of a typical LA)

1. amine group confers which type of properties?
2. aromatic group - confers what?
3. ester or amide linkage - determines what?
4. molecular size - influences rate of what?

Answer 3

1. hydrophilic
2. hydrophobic (& lipophilic)
3. route of metabolic degradation and potential allergic reactions
4. dissocation of local anesthetics from their receptor sites

Question 4

(Pharmacokinetics)

1. determined by site of injection, dosage, presence of vasoconstricting agent, and pharmocological profile of the la agent itself

(pKa vs pH)

1. pH is critical
2. LA are weak acids or bases?

Answer 4

2. weak bases (slightly soluble) - (marketed as HCl salts)

Question 5

Answer 5

Question 6

understand what’s going on here

Answer 6

Question 7

and this…

Answer 7

and this…

Question 8

and this…

Question 9

1-3 Epinephrine added to the solution of local anesthetic can cause what effects?

Answer 9

1. prolong drug duration by decreasing blood flow (local vasoconstriction)
2. decrease systemic toxicity by slowing absorption
3. delay healing or cause local tissue necrosis or edema

Question 10

(Metabolism)

1. The rate of metabolism and the metabolic by-products are important in assessing what?
2. Esters are hydrolyzed in plasma by what?
3. what is more rapidly metabolized… esters or amides?
4. Amides are degraded mainly where?

Answer 10

1. the toxicity of local anesthetics
2. serum cholinesterases
3. esters (thus have very short serum-half life (1 min for procaine) (also degraded in liver to small extent)
4. mainly in the liver via de-alkylation (so may cause problems in pateitns with hepatic insufficinecty)

Question 11

(Excretion)

1. parent drug and metabolites excreteed by what?

Answer 11

1. kindeys