local anesthetis

Question 1

how are ester and amide linked local anesthetics metabolized?

Answer 1

• Ester-linked local anesthetics are metabolized by tissue and plasma esterases (pseudocholinesterases).
• Amide-linked local anesthetics are in general degraded by liver microsomal cytochrome P450.

Question 2

MECHANISM OF ACTION

Answer 2

• Local anesthetics block voltage-gated sodium channels.
• Local anesthetics bind to receptors near the intracellular end of the channel and block the channel.
• Sufficient concentrations of a local anesthetic applied to a nerve fiber abolish action potentials.

Question 3

short acting local anesthetics?

Answer 3

• Procaine and chloroprocaine are short-acting

Question 4

Intermediate acting local anesthetics

Answer 4

• Lidocaine, mepivacaine, and prilocaine are intermediate-acting.

Question 5

Long acting Local anesthetics

Answer 5

• Tetracaine, bupivacaine, etidocaine and ropivacaine are long-acting.

Question 6

Toxiicity of Local anesthetics?

Answer 6

• Ultimately, local anesthetics are absorbed from the site of administration.
• If blood levels rise too high, effects on several organs systems may be observed.

Question 7

Toxicity: Central Nervous System

- how do you tx with large doses of LA?

Answer 7

When large doses must be given, premedication with a benzodiazepine provides significant prophylaxis against seizures

Question 8

Toxicity: CV System?

Answer 8

• Local anesthetics block sodium channels and thus depress cardiac pacemaker activity, excitability and conduction.
• With the exception of cocaine they also depress strength of cardiac contraction and cause arteriolar dilation, leading to hypotension.
• Cocaine may cause vasoconstriction and hypertension; also cardiac arrhythmias.

Question 9

What drug is more cardiotoxic than other Local anesthetics?

Answer 9

Bupivacaine

Question 10

Toxicity: Blood

- Prilocaine

Answer 10

Large doses of prilocaine during regional anesthesia may lead to accumulation of the metabolite o-toluidine, an oxidizing agent capable of converting hemoglobin to methemoglobin

Question 11

Allergic reactions are rare in which group of local anesthetics?

Answer 11

• Amides are not metabolized to p-aminobenzoic acid.

* Allergic reactions to agents of the amide group are extremely rare.

Question 12

Procaine metabolites can inhibit what type of drugs?

Answer 12

Sulfonamides