Local Anesthesia

Question 1

In the U.S. approximately___`% of the population avoid dental care due to fear

Answer 1

10

Question 2

What are the desirable Properties for local anesthesia?

Answer 2

1) No Irritation to tissue
2) No permanent alteration
3) Low systemic toxicity
4) Effective if injected into tissue or mucous membranes 5) Short onset
6) Long of enough duration of action for the procedure
7) Potent yet not harmfully concentrated
8) Not elicit allergic reaction
9) Readily undergo biotransformation
10) Sterile or capable of being sterilized by heat without deterioration

Question 3

____ ____ is the cornerstone of all anesthesia?

Answer 3

Local anesthesia

Question 4

____ _____ Prevents generation and /
or conduction of a nerve
impulse

Answer 4

Local anesthesia

Question 5

The least experience of pain which a subject can recognize

Answer 5

Pain threshold

Question 6

The greatest level of pain which a subject is prepared to tolerate

Answer 6

Pain Tolerance

Question 7

the __________ fluid is more positively charged.

Answer 7

extracellular fluid

Question 8

The _________ fluid is more negatively charged

Answer 8

intracellular fluid

Question 9

What are the five stages of Nerve Impulse Transmission?

Answer 9

1. resting phase channel closed
2. Fibre stimulated, channel opens sodium enters
3. Cell depolarized, channel closes.
4. Potassium exits down concentration and electrical gradients.
5. Fibre repolarized Na/K pump restores balance.

Question 10

Where do local anesthetics work ?

Answer 10

Nerve membrane is where local anesthesia

exert their pharmacological actions

Question 11

– Local anesthesia binds to specific receptor on the

Na channel, preventing from opening.

Answer 11

Specific Receptor Theory

Question 12

__ Fiber conducts pain signals?

Answer 12

C fiber

Question 13

Which fibers are faster A delta and Alpha OR C fibers

Answer 13

A alpha and delta

Question 14

_____ ____ insulates axons electrically

and pharmacologically

Answer 14

Myelin sheath

Question 15

Where are sodium channels most abundant?

Answer 15

Nodes of ranvier

Question 16

- nodes needs to be blocked and - mm length needed to ensure effective anesthesia

Answer 16

2-3 nodes

8-10 mm

Question 17

How does local anesthesia work?

Answer 17

• Decrease permeability of ion channels to Na

• Nerve block by local anesthesia is a
Non-depolarizing block

Question 18

majority form of local anesthesia are _______ ______.

Answer 18

tertiary amine

Question 19

What two Local anesthetics are 2ndary amines?

Answer 19

prilocaine and hexylcaine

Question 20

t/f: All local anesthetics are amphipathic

except…benzocaine

Answer 20

true

Question 21

Antihistamine and anticholinergics have______

local anesthetic properties

Answer 21

weak

Question 22

What are the two types of Local anesthetics?

Answer 22

Amides and esters

Question 23

Resist hydrolysis, excrete unchanged in urine

Answer 23

amide

Question 24

Readily hydrolyzed in aqueous solution

Answer 24

ester

Question 25

``` All of the following are examples of _______: – Procaine – Propoxycaine – Tetracaine – Cocaine – Benzocaine – Dyclonine ```

Answer 25

Esters

Question 26

``` All of the following are examples of _______: – Lidocaine – Etidocaine – Mepivacaine – Bupivacaine – Prilocaine – Articaine ```

Answer 26

Amides

Question 27

______ doesn’t have hydrophilic group Therefore, its not suitable for injection but nice topical !!

Answer 27

Benzocaine

Question 28

Local Anesthesia combine with acids to form local anesthetic salt (HCl). This makes them ______ basic compunds

Answer 28

WEAK

Question 29

dissociation constant

Answer 29

pKa

Question 30

Relative proportion of ionic form depends on_____.

Answer 30

pKa

Question 31

t/F: When pH of solution = pKa, you have 50/50 RN/RNH+

Answer 31

true

Question 32

What two Factors are involved in the action of local anesthesia

Answer 32

1) Diffusion through nerve sheath | 2) Binding at receptor site

Question 33

______ ____ is able to freely diffuse across the neuron axon membrane and into the axoplasm.

Answer 33

free base

Question 34

t/F; Once in the axoplasm, the free base is then changed back into the ionized form and the process continues until all of the anesthetic is in the axoplasm.

Answer 34

true

Question 35

t/f: increased translates to slow onset because few free base molecule available to diffuse

Answer 35

true

Question 36

decreased pKa will have_____ onset

Answer 36

faster

Question 37

_______ pH determines the ease for nerve blockade

Answer 37

Extracellular

Question 38

Inflamed or infected tissue is much more difficult to get | adequate anesthesia b/c _____ or ______

Answer 38

lower pH or ↑H+

Question 39

t/f: Keep low pH equates ↑effective shelf live of local anesthesia

Answer 39

true

Question 40

Most local anesthesia have pH ____ to ___

Answer 40

5.5 to 7

Question 41

from the innermost to the outermost, what is the composition of peripheral nerve

Answer 41

Endoneurium --> Perineurium ---> Epinerium

Question 42

_______ is greatest barrier for diffusion because Slower diffusion is dependent on the thickness

Answer 42

Perineurium

Question 43

______ fiber tends to innervate proximal region (molars)

Answer 43

Mantle

Question 44

______ fiber innervates more distal points (incisors)

Answer 44

Core

Question 45

Complete conduction blockade requires ______ and ______.

Answer 45

Volume and Concentration.

Question 46

What happen to injected drug?

Answer 46

– Absorbed by nonneural tissue – Diluted by interstitial fluid – Removed by capillaries and lymphatic system – For Ester-type: immediate enzymatic hydrolysis

Question 47

_____ pKa posses rapid onset of action

Answer 47

Lower

Question 48

t/f: Greater lipid solubility relates to intrinsic potency because the nerve membrane is 90% lipid.

Answer 48

true

Question 49

t/f: Increased protein binding will increase duration because nerve membrane is 10% protein.

Answer 49

true

Question 50

the result of the following is? – “reverse” of anesthetic induction pattern – Intraneural concentration exceeds extraneural concentration

Answer 50

recovery from nerve block.

Question 51

Recurrence of Immediate profound anesthesia results in what two things?

Answer 51

– Reduced concentration at mantle fibers – Residual local + newly deposited supply = immediate profound anesthesia

Question 52

– ↑ Tolerance to drug after repeated administration

Answer 52

Tachyphylaxis

Question 53

What factors can increase the tolerance to drug after repeated administration?

Answer 53

``` – Edema – Localized hemorrhage – Clot formation – Transudation – Hypernatremia – ↓pH of the tissue ```

Question 54

t/f: lipid solubility influences potency.

Answer 54

true

Question 55

t/f: pKa influences onset

Answer 55

true

Question 56

t/f: protein binding influences duration

Answer 56

true