Local Anesthetics

Question 1

What is the MOA of local anesthetics?

Answer 1

Bind reversibly to voltage gated Na channels in nerves and block ion movement through the channel pore.

Question 2

What is the difference between agents that have ester linkages vs. those with amide linkages?

Answer 2

Ester linkages–> more prone to hydrolysis, shorter duration of action.

Amide linkages–> longer duration of action.

Question 3

How are ester-type agents metabolized?

Answer 3

In the plasma by circulating butyrylcholinesterase enzymes.

Question 4

How are the amide-linkage agents metabolized?

Answer 4

In the liver by cytochrome P450, then excreted in urine as charged substances.

Question 5

What dictates how fast and potenet a local anesthetic is?

Answer 5

Size and how lipophilic the local anesthetic is.

Question 6

What can be given to avoid CNS toxicity of local anesthetics when a high doses are needed?

Answer 6

Benzodiazepines to prevent seizure activity. They raise the seizure threshold.

Question 7

What are the two major forms of local anesthetic toxicity?

Answer 7

1) Systemic effects following absorption of local anesthetics (CV and CNS).
2) Direct neurotoxicity when given in close proximity to the spinal cord.

Question 8

What type of anesthetic is Benzocaine and what is it used for clinically?

Answer 8

• Ester
• Used as topical agent for dermatological conditions, hemorrhoids, premature ejaculation, and as an anesthetic lubricant.

Question 9

What type of anesthetic is Bupivacaine and what is it used for clinically?

Answer 9

• Amide
• Long duration of action, will provide extended anesthesia.
• sensory>motor

Question 10

What type of anesthetic is cocaine and what is it used for clinically?

Answer 10

• Ester
• Blockade of nerve impulses and local vasoconstricting actions secondary to its ability to inhibit local norepinephrine reuptake.
• Primarily used as topical anesthetic of upper respiratory tract.

Question 11

What type of anesthetic is dibucaine and what is it used for clinically?

Answer 11

• Amide

- Topical use only due to toxicity.

Question 12

What type of anesthetic is Lidocaine and what is it used for clinically?

Answer 12

• Amide (prototypical one)
• Produces faster, more intense, longer lasting, and more extensive anesthesia than an equal dose of procaine.
• alternative choice for individuals sensitive to ester-type local anesthetics.

Question 13

What type of anesthetic is procaine and what is it used for clinically?

Answer 13

• Ester
• Only used for infiltrating anesthesia.
• Can inhibit the sulfonamide antibiotics.

Question 14

Name the class, duration of action, and common clinical uses for Lidocaine

Answer 14

• Amide
• Medium duration of action
• Prototypical amide local anesthetic; alternative choice for ester-type local anesthetic sensitivity.
• Also used as anti-arrhythmic

Question 15

Name the class, duration of action, and clinical uses for Bupivacaine

Answer 15

• Amide
• Long duration of action
• Used for prolonged anesthesia

Question 16

Name the class, duration of action, and clinical uses of benzocaine

Answer 16

• Ester
• topical agent only
• dermatological condition, hemorrhoids, premature ejaculation, an anesthetic lubricant

Question 17

Name the class, duration of action, and clinical use of Cocaine

Answer 17

• Ester
• Medium duration of action
• Primarily used as topical anesthetic of the upper respiratory tract

Question 18

Name the class, duration of action, and clinical uses of procaine

Answer 18

• Ester
• Short duration of action
• Only used for infiltration anesthesia