FB - Local Anaesthetics

Question 1

What are the two main types of local anesthetics?

Answer 1

Ester and amide local anesthetics.

Question 2

How do local anesthetics function?

Answer 2

By blocking sodium channels, stopping axonal conduction.

Question 3

What are common side effects of local anesthetics?

Answer 3

Numbness, tingling, and in some cases, allergic reactions.

Question 4

What factor increases the potency of local anesthetics?

Answer 4

Higher lipid solubility of the local anesthetic.

Question 5

What is the difference between metabolism of ester-type vs. amide-type local anesthetics?

Answer 5

Ester-type are metabolized by plasma or tissue esterases, amide-type by the liver.

Question 6

How are local anesthetics absorbed?

Answer 6

Typically absorbed through the site of administration.

Question 7

What is a significant concern with local anesthetic toxicity?

Answer 7

Systemic toxicity, particularly affecting the CNS and cardiovascular system.

Question 8

In what fields are local anesthetics commonly used?

Answer 8

Dentistry and, minor surgical procedures

Question 9

What determines the duration of action of local anesthetics?

Answer 9

Their lipid solubility, plasma protein binding capacity and local blood-flow.

Question 10

How does nerve size affect local anesthetic action?

Answer 10

Smaller nerves are more readily blocked than larger ones.

Question 11

What is the clinical significance of local anesthetics’ firing frequency?

Answer 11

Higher firing frequency nerves are more susceptible to blockade.

Question 12

What role does myelination play in local anesthetics’ effectiveness?

Answer 12

Myelinated nerves are blocked more easily than unmyelinated ones.

Question 13

How does the pH of the tissue influence local anesthetics?

Answer 13

Acidic tissue environment can reduce the efficacy of local anesthetics.

Question 14

What is the role of vasoconstrictors in local anesthetic preparations?

Answer 14

To reduce systemic absorption and toxicity.

Question 15

How are ester-type local anesthetics metabolized?

Answer 15

Rapidly hydrolyzed by plasma cholinesterases.

Question 16

What are examples of ester-type local anesthetics?

Answer 16

Procaine, Benzocaine, Tetracaine.

Question 17

What are examples of amide-type local anesthetics?

Answer 17

Lidocaine, Bupivacaine, Prilocaine.

Question 18

What is a unique property of Bupivacaine among local anesthetics?

Answer 18

More cardiotoxic than most other amide local anesthetics

Question 19

What can cause systemic toxicity in local anesthetics?

Answer 19

Prolonged application, overdose or inadvertent intravascular injection.

Question 20

What is the risk of using local anesthetics in patients with cardiac conditions?

Answer 20

Potential exacerbation of cardiac arrhythmias.

Question 21

How does protein binding relate to the duration of action in local anesthetics?

Answer 21

Higher protein binding is associated with a longer duration.

Question 22

What is the risk with Ester-type anesthetics?

Answer 22

Potential for allergic reactions in a small proportion of patients due to para-aminobenzoic acid formation.

Question 23

How does pH affect Lidocaine absorption?

Answer 23

Alkaline pH increases Lidocaine availability at target sites and efficacy.

Question 24

What is a common use of topical local anesthetics?

Answer 24

Minor procedures like skin suturing or venipuncture.

Question 25

How do local anesthetics affect pain and temperature sensation?

Answer 25

They block pain and temperature sensation before motor blockade.

Question 26

Why are local anesthetics used in spinal and epidural anesthesia?

Answer 26

To provide regional anesthesia for surgeries.

Question 27

Why is Bupivacaine used in epidural anesthesia?

Answer 27

For its relative long duration of action.

Question 28

What is a potential side effect of Prilocaine?

Answer 28

Methemoglobinemia, especially in high doses.

Question 29

Why are amide anesthetics generally safer than esters?

Answer 29

Less allergenic .

Question 30

How does the use of local anesthetics differ in inflamed tissues?

Answer 30

They are less effective due to acidic tissue pH.

Question 31

What is the impact of local anesthetic use in labor?

Answer 31

It can provide pain relief during labor .

Question 32

Why is careful dosing important in local anesthetics?

Answer 32

To avoid systemic toxicity.

Question 33

What is the significance of vasodilator effect in local anesthetics?

Answer 33

It can cause faster absorption in non-target tissues due to increased blood flow, increasing the risk of systemic toxicity.

Question 34

How do local anesthetics exert their effects on nerve cells?

Answer 34

They inhibit sodium channels, preventing depolarization and blocking nerve impulse conduction.

Question 35

What are the physical properties essential for the action of local anesthetics?

Answer 35

Lipid solubility for penetration of cell membranes

Question 36

How does the pKa of a local anesthetic influence its onset of action?

Answer 36

The pKa affects the proportion of the anesthetic in the lipid-soluble uncharged form, which can penetrate nerve membranes.

Question 37

How does the intermediary link in local anesthetics affect their classification?

Answer 37

The link type (ester or amide) determines the class and influences metabolism and potential for allergic reactions.

Question 38

What are the implications of local anesthetic toxicity?

Answer 38

It necessitates careful dosing and monitoring, especially in high-risk or sensitive patient populations.