Care Viii - Pharmacology - Local Anesthetics - Lecture 25

Front 1

Drugs used to prevent or suppress sensation in or on a confined area of the body.

Back 1

local anesthetics

Front 2

How do local anesthetics work?

Back 2

They act by blocking nerve impulses. (no action potential)

Front 3

What are the ideal properties of local anesthetics?

Back 3

1. effects should be temporary
2. no local toxic effects (such as skin or nerve damage)
3. low systemic toxicity
4. effective whether it is injected or applied topically
5. the time for onset should be brief
6. duration of action appropriate for intended purpose

Front 4

true or false:
No local anesthetics will have ALL of the ideal properties.

Back 4

true

Front 5

What was the 1st local anesthetic?

Back 5

cocaine

Front 6

What are the two classes of local anesthetics?

Back 6

1. amides
2. esters

Front 7

Which of the two classes of local anesthetics is newer?

Back 7

amides

Front 8

Which of the two classes of local anesthetics is older?

Back 8

esters

Front 9

Where are the amides metabolized?

Back 9

in the liver

Front 10

Where are the esters metabolized?

Back 10

in plasma (hydrolysis)

Front 11

What breaks down esters?

Back 11

Acetylcholinesterase

Front 12

There are more allergic reactions with _______ (amides/esters).

Back 12

esters

Front 13

What is the mechanism of action of local anesthetics?

Back 13

Their effect is on nerve impulses. They block action potential generation and propagation by blocking Na+ channels.

Front 14

With local anesthetics, you have be to careful with changes in ______.

Back 14

pH

Front 15

Most local anesthetics are ______ (weak/strong) ________ (acids/bases)

Back 15

weak bases

Front 16

Inflammation and infection increases ______ (acids/bases) in the body.

Back 16

acids

Front 17

___________(charged/uncharged) forms of local anesthetics blocks the channel.

Back 17

charged

Front 18

_________ (charged/uncharged) forms of local anesthetics goes across the membrane.

Back 18

uncharged

Front 19

The more acid there is, the less ________ (charged/uncharged) forms of local anesthetics.

Back 19

uncharged

Front 20

With a decrease in uncharged form of local anesthetics, you may need more anesthetic to work. This runs the risk of...

Back 20

toxicity

Front 21

Effects are ___________ dependent.

Back 21

frequency

Front 22

Binding is _______ dependent.

Back 22

voltage

Front 23

________ are frequency dependent.

Back 23

effects

Front 24

_________ is voltage dependent.

Back 24

binding

Front 25

The faster the neuron is firing, the better the pain control. (better block)

Back 25

frequency dependent

Front 26

Local anesthetics work best on...

Back 26

small, unmyelinated nerves

Front 27

Big, thick, highly myelinated nerves need _____ (more/less) anesthetic.

Back 27

more

Front 28

Which type of nerves is the most sensitive to local anesthetics?

Back 28

sensory

Front 29

Which type of nerves is the least sensitive to local anesthetics?

Back 29

motor

Front 30

Systemic absorption of local anesthetics has two effects. What are they?

Back 30

1. systemic toxicity
2. decrease the duration of action

Front 31

Most local anesthetics are _________ (vasoconstrictors/vasodilators).

Back 31

vasodilators

Front 32

Because most local anesthetics are vasodilators, they increase blood flow to ___________ and increase ___________.

Back 32

to the area of administration &
increase systemic absorption

Front 33

To decrease absorption of local anesthetics, __________ (a vasoconstrictor) is usually added to the solution.

Back 33

epinephrine

Front 34

Epinephrine should not be used on _____ (small/large) areas.

Back 34

small

Front 35

true or false:
Local anesthetics promote their own absorption.

Back 35

true

Front 36

Absorption of local anesthetics ________ (increases/decreases) their potency.

Back 36

decreases

Front 37

What is the only local anesthetic that is a vasoconstrictor?

Back 37

cocaine

Front 38

You need to be careful using epinephrine in ______ patients.

Back 38

cardiac

Front 39

What are the factors affecting absorption?

Back 39

-site
-concentration of local anesthetic
-degree of vasodilation produced by the local anesthetic

Front 40

Which site has the fastest absorption of local anesthetics?

Back 40

mucous membranes

Front 41

Increasing the concentration of local anesthetics ________ (speeds up/slows down) the absorption.

Back 41

speeds up

Front 42

Increasing the vasodilation of local anesthetics _________ (increases/decreases) absorption.

Back 42

increases

Front 43

What are the main reactions associated with the toxicity of local anesthetics?

Back 43

-CNS reactions
-cardiovascular reactions

Front 44

What are the CNS reactions associated with toxicity when low systemic levels of local anesthetics are present?

Back 44

-anxiety
-insomnia
-apprehension
-numbness around the mouth
-diplopia
(These effects resemble someone who has had too much caffeine.)

Front 45

What are the CNS reactions associated with toxicity when high systemic levels of local anesthetics are present?

Back 45

-CNS depression
-convulsions
-respiratory depression

Front 46

What are the cardiovascular reactions associated with the toxicity of local anesthetics?

Back 46

-arrhythmias
-decreased contraction
-hypotension
-cardiovascular collapse

Front 47

What are the uses of local anesthetics?

Back 47

- surface anesthesia
- infilration anesthesia
- nerve block
- spinal anesthesia
- epidural anesthesia
(i.v anesthesia)

Front 48

What is surface anesthesia?

Back 48

An anesthetic applied on the skin.

Front 49

What is infiltration anesthesia?

Back 49

An anesthetic injected into a small area.

Front 50

What is a nerve block?

Back 50

An anesthetic that blocks the whole nerve below the injection site.

Front 51

What is a side effect of spinal anesthesia?

Back 51

a very bad headache

Front 52

What is spinal anesthesia?

Back 52

A nerve block that is injected INTO the dura in the CSF.

Front 53

What is epidural anesthesia?

Back 53

A nerve block that is injected OUTSIDE of the dura.

Front 54

What is the difference between spinal anesthesia and epidural anesthesia?

Back 54

spinal - into the dura
epidural -outside the dura

Front 55

What are the important local anesthetics?

Back 55

1. Lidocaine
2. Mepivicaine
3. Prilocaine
4. Bupivicaine
5. Tetracaine
6. Procaine (Novocaine)
7. Cocaine
(He said we could skip Etidocaine and Articaine.)

Front 56

What is the gold standard of local anesthetics?

Back 56

Lidocaine

Front 57

Which of the LA's is the prototype amide?

Back 57

Lidocaine

Front 58

Which LA is the most widely used?

Back 58

Lidocaine

Front 59

Which LA has rapid absorption and duration of about an hour?

Back 59

Lidocaine

Front 60

Which two LA's have an intermediate duration?

Back 60

Mepivicaine and Prilocaine

Front 61

Which LA crosses the placental barrier and poses a higher risk to the fetus?

Back 61

Mepivicaine

Front 62

Which LA is not effective topically?

Back 62

Mepivicaine

Front 63

Which LA has little vasodilation?

Back 63

Prilocaine

Front 64

Which LA has less toxicity that Lidocaine?

Back 64

Prilocaine

Front 65

Which LA can produce Methemoglobinemia?

Back 65

Prilocaine

Front 66

Which LA has a long duration (up to 12 hours)?

Back 66

Bupivicaine

Front 67

Which LA has a higher cardiac toxicity than Lidocaine?

Back 67

Bupivicaine

Front 68

Which LA is a potent ester?

Back 68

Tetracaine

Front 69

Which LA has a slower onset than Lidocaine?

Back 69

Tetracaine

Front 70

Which LA has a longer duration than procaine?

Back 70

Tetracaine

Front 71

Which LA is a good topical anesthetic?

Back 71

Tetracaine

Front 72

Which LA is used for labor and delivery?

Back 72

Tetracaine

Front 73

What was the first synthetic local?

Back 73

Procaine

Front 74

Which LA has a low potency, slow onset, short duration of action, and low toxicity?

Back 74

Procaine

Front 75

Which LA can be metabolized to paraaminobenzoic acid? (which some people can be allergic to)

Back 75

Procaine

Front 76

Which LA is used for ENT procedures?

Back 76

Cocaine

Front 77

What are the topical local anesthetics?

Back 77

- Benzocaine
- Butacaine sulfate
- Dyclonine HCl
- Lidocaine
- Tetracaine

Front 78

What is special about Dyclonine HCl?

Back 78

It is neither an ester nor an amide.

Front 79

What drug can be given as a substitute for patients that cannot tolerate amides or esters?

Back 79

Diphenhydramine (Benedryl)