7 - Local Anesthetics

Question 1

Chemical structural components of local anesthetics

Answer 1

Aromatic Moiety
Linker region
Substituted Amine

Question 2

How are local anesthetics classified?

Answer 2

Based on the linker region

Question 3

Local Anesthetics - Esters

Answer 3

Cocaine
Procaine
Benzocaine
Proparacaine
Tetracaine

Question 4

Local Anesthetics - Amides

Answer 4

Lidocaine
Articaine
Bupivacaine
Mepivacaine
Prilocaine
Ropivacaine

Question 5

Local Anesthetics - Ketone

Answer 5

Dyclonine

Question 6

Local Anesthetics - Ether

Answer 6

Pramoxine

Question 7

Tetracaine Duration

Answer 7

30 - 60 min

Question 8

Procaine Duration

Answer 8

30 - 60 min

Question 9

Chloroprocaine Duration

Answer 9

30 - 60 min

Question 10

Cocaine Duration

Answer 10

30 - 60 min

Question 11

Bupivicaine Duration

Answer 11

2 - 5 hours

Question 12

Lidocaine Duration

Answer 12

1 - 3 hours

Question 13

Etidocaine Duration

Answer 13

2 - 4 hours

Question 14

Mepivicaine Duration

Answer 14

1.5 - 3 hours

Question 15

Tetrodotoxin

Answer 15

A potent Na+ Channel blocker. Not used as an anesthetic because it is too potent/deadly.

Produced in the liver of a Puffer fish

Question 16

Saxitoxin

Answer 16

“Shellfish Poisoning”

A potent Na+ Channel blocker, produced by algae which is then ingested by shellfish.

Question 17

Why administer epinephrine with local anesthetic when injecting?

Answer 17

It’s a damn vasoconstrictor, dude. It prevents the anesthetic from spreading, prolonging its effect, and keeping it from harming the rest of your shit

Question 18

Advantages/considerations of liposomal administration of the new formulation of Bupivacaine

Answer 18

The reservoir is emptied very slowly, so there is long-lasting effect (48 - 72 hours).

Harder to control the possible toxic effects though

Question 19

Ways to administer anesthesia

Answer 19

Topical
Infiltration (Field Block)
Nerve Block
Intravenous Regional
Spinal
Epidural

Question 20

Steps for Intravenous Regional Anesthesia

Answer 20

Exsanguinate the area with a tourniquet

Inject anesthesia distal to the tourniquet (to block systemic distribution)

Question 21

Difference between Epidural Anesthesia and Spinal Anesthesia

Answer 21

Epidural = Outside the dura mater
Sinal = Penetrate the dura mater (usually at the level of the cauda equina)

Question 22

Local Anesthetics - Master List of CNS Side Effects

Answer 22

Agitation
Convulsions
Psychosis
Depression
Sedation
Loss of Consciousness

Question 23

Local Anesthetics - Master List of Cardiovascular Side Effects

Answer 23

Decreases in myocardial excitability
Decreases in conduction rate
Decreases in force of contraction
Vasodilation
(Others may occur when local anesthetics are used with epinephrine)

Question 24

Local Anesthetics - Master List of Smooth Muscle Side Effects

Answer 24

Relaxation of vascular and bronchial muscles

Question 25

Local Anesthetics - Master List of Skeletal Muscle Side Effects

Answer 25

Reduced neuromuscular transmission

Question 26

How many isoforms of voltage-gated sodium channels do humans express?

Answer 26

8 (Though local anesthetics are nonselective)

Question 27

Which sodium channels are preferentially expressed in peripheral neurons?

Answer 27

Nav1.3 Nav1.7 Nav1.8 Nav1.9

Question 28

Expression of Nav1.3 in peripheral sensory neurons

Answer 28

Embryogenesis - Normally expressed Adult - Continued expression in sympathetic neurons Post-Injury - Upregulated in DRG neurons

Question 29

Expression of Nav1.7 in peripheral sensory neurons

Answer 29

DRG Neurons - Preferentially expressed | Sympathetic Neurons - Preferentially expressed

Question 30

Expression of Nav1.8 in peripheral sensory neurons

Answer 30

DRG Neurons - Selectively expressed

Question 31

Expression of Nav1.9 in peripheral sensory neurons

Answer 31

DRG Neurons - Selectively expressed in small-diameter, nonpeptidergic DRG Neurons

Question 32

Which sodium channels provide the most information about pain?

Answer 32

Nav1.8 | Nav1.9

Question 33

Inherited Erythromelalgia

Answer 33

``` Nav1.7 gain-of-function Mutation Episodes of intense pain and erythema Affecting one or both hands Evoked by physical activity or cold No good treatment ```

Question 34

Paroxysmal Extreme Pain Disorder

Answer 34

``` Nav1.7 Mutation Starts very early Affects sympathetic nervous system Can have Harlequin Syndrome Scream when they defecate or get touched in perineum Responds to Carbamazepine ```

Question 35

Types of A Fibers

Answer 35

A α A β A γ A δ

Question 36

Types of C Fibers

Answer 36

Sympathetic | Dorsal Root

Question 37

B Fibers

Answer 37

Preganglionic Sympathetic | Myelinated

Question 38

A α Fibers

Answer 38

Afferent to muscles & joints Efferent from muscles & joints Myelinated

Question 39

A β Fibers

Answer 39

Afferent to muscles & joints Efferent from muscles & joints Myelinated

Question 40

A γ Fibers

Answer 40

Efferent to muscle spindles | Myelinated

Question 41

A δ Fibers

Answer 41

Sensory roots Afferent peripheral nerves Myelinated

Question 42

Sympathetic C Fibers

Answer 42

Postganglionic | Unmyelinated

Question 43

Dorsal Root C Fibers

Answer 43

Sensory Roots Afferent peripheral nerves Unmyelinated

Question 44

Relationship between diameter of fibers and their susceptibility to local anesthetic

Answer 44

Inverse | The larger a fiber is, the less susceptible it is to local anesthetic

Question 45

TRP Channels

Answer 45

Sensitive to heat/cold/temperature change Selectively expressed in pain fibers Opened by Capsaicin Provide a back door for selectively targeting fibers

Question 46

How do we get QX-314 into the cell interiors of pain fibers, when it normally can't penetrate the plasma membrane?

Answer 46

Administer with Capsaicin. QX-314 goes through the TRPV1 channel to enter the cell, and finally reach its target, the Na+ channel inside

Question 47

TRP Receptors on Pain Fibers

Answer 47

TRPA1 | TRPV1

Question 48

TRP Receptors on Itch Fibers

Answer 48

TRPV1 H1R TRPA1 MrgprA3