Local Anesthetics

Front 1

_________ are drugs used to prevent pain by inhibiting the conduction of nerve impulses along the nerve fiber

Back 1

Local Anesthetics

Front 2

the degree of local anethesia obtained is dependent on

Back 2

the method of administration

Front 3

Methods of adminsitration include:

Back 3

- surface (applied directly to surface that is to be anesthetized)
- topical (applied to skin the form of cream/gel)
- Infiltration (Injected below skin)
- Nerve block (injected close to major nerve bundle)
- epidural (injected into the outer part of the spinal cord)
- spinal (injected into the spinal canal)

Front 4

Local anesthetics are _______ bases

Back 4

weak

Front 5

the ph of local anesthetics is

Back 5

~4.5

Front 6

The first local anesthetic agent in dentistry was

Back 6

cocaine

Front 7

Once anesthetic tissue solution placed into tissue, it rapidly changes to a more neutral ph of

Back 7

~7.4

Front 8

In aqueous solution (e.g. body fluids) local anesthetic will dissociate into

Back 8

- nonionized form (uncharged)
and
- ionized form (charged)

Front 9

the chemical apsects of local anethesia are composed of an aromatic segement with either an ________ bond or an _______ bond to a basic side chain

Back 9

- amide
- ester

Front 10

Local anesthetics of intermediate potency and duration of action such as _________, _________, and __________ are mainly used in dentistry

Back 10

- lidocaine
- mepivacaine
- prilocaine

Front 11

most anesthetics are combined with an _______ such as hyrochloride (HCI) to form a salt, because it is more stable and soluble than the base

Back 11

- acid

Front 12

When injected, the anesthetic is not in an active form; to be active the nonionized or uncharged portion of the local anesthetic acts like a _________, lipid soluble compound that will readily transverse the lipid nerve cell membrane

Back 12

nonpolar

Front 13

Once inside the nerve, ionized molecules block the __________ in the membrane, thus decreasing the permeability (passage) of the nerve membrane to ________ ions

Back 13

- sodium channels
- sodium

Front 14

when the anesthetic blocks the sodium channels it prevents the generation of ___________

Back 14

action potentials

Front 15

The ______ the pKa value of the anesthetic, the more rapid onset of action

Back 15

lower

Front 16

Amides consist of a Nitrogen bond and include

Back 16

- Lidocaine
- mepivicaine
- Prilocaine
- articaine
- bupivicaine

Front 17

Esters consist of double bond and include

Back 17

- Benzocaine
- cocaine
- tetracaine

Front 18

_________ is a less potent vasoconstrictor than epinephrine but is more likely to cause an increase in blood pressure

Back 18

- Levonordefrin

Front 19

__________ is available in an injectable form 0.54% solution with epinephrine 1:200,000 and has a slow onset and may last 2-3 times longer than lidocaine and mepivacaine, lasting up to 7 hours.

Back 19

Bupivicaine (Marcaine)

Front 20

________ is stronger than lidocaine but has an increased incidence of parethesia

Back 20

Articaine (Septocaine)

Front 21

_______ is a more potent vasoconstrictor than levonordefrin

Back 21

Epinephrine

Front 22

The maximum safe dose for epinephrine in healthy individuals is _______ and in cardiac patients is _______

Back 22

- 0.2 mg
- 0.04 mg

Front 23

__________ stimulates both a- and B- adrenergic (sympathetic) receptors as the same time

Back 23

Epinephrine

Front 24

_________ stimulates a- adrenergic (sympathetic) receptors, with little to no effect on the B- adrenergic receptors

Back 24

Levonordefrin

Front 25

There are two vasoconstrictors used in local anesthetics:

Back 25

- epinephrine
- levonordefrin (Neo-Cobefrin)

Front 26

The addition of a vasoconstrictor counteracts the vasodialating effects of the anesthetic, thus the vasoconstrictor will:

Back 26

- constrict blood vessels in tissue resulting in a decrease blood flow to the site of injection
- Slow the absorption of the agent into the bloodstream
- Lower the blood levels that would decrease the risk of an overdose
- Decrease or prevent bleeding (hemostasis) at the site of injection
- allow higher concentration of local anesthetic remaining in the nerve for a longer time, thus increasing the duration of anesthetic effect

Front 27

Although the main systemic effect of local anesthetics is on the central nervous system (crosses the blood-brain barrier), in high blood concentrations there are _________ effects including _______ and _______. At toxic levels they may cause ________ and _________.

Back 27

- cardiovascular
- hypotension
- cardiac depression
- seizures
- cardiac arrhythmias

Front 28

Death from local anethetics overdose is usually due to

Back 28

respiratory failure

Front 29

Adverse reactions involving epinephrine include

Back 29

- palpitations
- tachycardia (rapid heart rate)
- anxiety
- headache
- tremor
- hypertension

Front 30

________ is a rare uncommon adverse reaction usually with high doses of prilocaine, but it may also occur with articaine and topical benzocaine and is clinically characterized by cyanosis (low oxygen)

Back 30

Methemoglobinemia (excessive methemoglobin levels)

Front 31

3 steps in Treatment of toxicity

Back 31

- Monitor vitals
- administer oxygen
- Emergency operations

Front 32

Selection of local anesthetic for the dental patient depends upon:

Back 32

- Duration of dental procedure; amoun to time pain control is required
- Anticipation of postoperative pain
- Contraindications for a specific anesthetic
- Routine procedures (is use of justified)
- Children and pregnant patients

Front 33

________ is preferred in children an pregnant patients. For conventional dental procedures _________, _________, ___________, or ____________ can be considered

Back 33

- Lidocaine
- articaine, lidocaine, mepivacaine, prilocaine

Front 34

Documentation in the treatment record must include

Back 34

the type and dosage of local anesthetic in milligrams. If vasoconstrictor used, must be noted in either mg or concentration

Front 35

Anesthetics are ______ effective in inflamed, acidic tissue

Back 35

less

Front 36

________ contains Levonordofrin as a vasoconstrictor

Back 36

Mepivicaine

Front 37

True/True/False/False
Amides are the local anesthetics most likely to cause an allergic reaction. This property is a result of their metabolism into paraminobenzoic acid (PABA)

Back 37

FALSE / FALSE
-Amide local anethetics rarely cause an allergic reaction.
- Esters have a much greater allergic potential because of their metabolism into PABA

Front 38

True/ False
Amides and esters are both primarily metabolized in the blood plasma

Back 38

False
- Amides are primarily metabolized in the liver, and esters are hydrolyzed to PABA by blood plasma pseudocholinesterases and liver esterases

Front 39

Lidocaines are used for all of the following EXCEPT one:
a) Local Anesthetic
b) blood pressure regulation
c) antiarrhythmia
d) antiplatelet agent

Back 39

B) blood pressure regulation
- Lidocaine is an amide local anesthetic that can be administered as a topical, infiltration, block, spinal, epidural, and caudal anethesia. It can also be used intravenously to treat cardiac arrythmial during surgery

Front 40

Which of the following must occur for a local anesthetic to be absorbed?
1) Weak acid form
2) Weak base form
3) Primarily nonionized
4) primarily ionized

a) 1 & 4
b) 2 & 4
c) 2 & 3

Back 40

C) 2 & 3
- Local anethetics must be a weak base form that is equilibrated in a fat soluble free base and a water soluble salt. the more acidic the environment is (and more ions present) the less effective the local anesthetic's action will be

Front 41

A 45 year old alcoholic patient with suspected cirhosis needs an extraction of a badly abcessed tooth. The amount of amide local anesthetic and other drugs should be
a) increased
b) decreased
c) unaffected

Back 41

b) decreased
- Patients with severe liver disease or alcoholics may be unable to break down the local anesthetic, and they may suffer from systemic toxicity

Front 42

A patient is taking cimetidine (Tagament) for a gastric ulcer. this drug could have what clinical effect if the patient required large doses of local anesthetic?
a) Increase lidocaine metabolism
b) decrease lidocaine metabolism
c) no effect on lidocaine metabolism

Back 42

B) decrease lidocaine metabolism
- Cimetidine decreases hepatic blood flow, slowing the metabolism of the amides. Although the small doses used in dentistry would probably not cause toxicity, large doses could become toxic

Front 43

All of the following are components of local Anesthetics except one:
A) vasoconstrictor
B) Sodium chloride
C) Antioxidant
D) Antihistamine
E) Sodium hydroxide

Back 43

D) antihistamine

Front 44

All of the following are amides except
a) Mepivicaine
b) Bupivacaine
c) Procaine
d) Prilocaine

Back 44

c) procaine
- Procaine is a PABA ester that is used as an antiarrhythmic agent and combined with penicillin to form procaine penicillin G. It is not used as a local anesthetic in dentistry because of allergic reactions

Front 45

All of the following are esters except one
a) Mepivicaine
b) Procaine
c) Propoxycaine
d) Tetracaine

Back 45

a) mepivicaine
- Mepivicaine is an amide local anesthetic

Front 46

What is the most common formulation of local anesthetic used in dentistry today?
a) lidocaine 2% 1:200,000
b) Mepivicaine 3% plain
c) Lidocaine 2% 1:100,000
d) Mepivicaine 3% 1:20,000

Back 46

c) Lidocaine 2% with 1:100,000 epinehprhine

Front 47

Vasoconstrictors are added to local anesthetics for all of the following reasons except one:
a) increase depth of anesthesia
b) shorten duration of action
c) reduces systemic toxicity
d) reduce bleeding at injection site

Back 47

b) shorten duration of action

Front 48

The most common local adverse reaction to local anesthetic is
a) central nervous system excitation
b) psychogenic shock
c) physical injury at injection site: hematoma
d) lidocaine toxicity
e) malignant hyperthermia

Back 48

c) physical injury at injection site: hematoma
-due to administration of a excessive volume too quickly to be accepted by the tissues

Front 49

Which of the following is the most commonly used topical anesthetic?
a) lidocaine 2% 1:200,000
b) Mepivicaine 3% plain
c) Benzocaine 20%
d) articaine 4%

Back 49

c) benzocaine 20%
- used in dental products and many over the counter products for teething, sunburn, and other skin irritations

Front 50

What is the mechanism of action of local anesthetic?
a) blocks nerve by inducing anesthesia
b) decreases permeability of nerve membrane, preventing depolarization
c) decreases perception of pain
d) decreases reaction to pain

Back 50

b) decreases permeability of nerve membrane, preventing depolarization
- nerve impulses are transmitted when the nerve action potential opens the sodium and potassium ion channels in the nerve membrane. the inward flow of sodium ions and the outward flow of potassium ions repolarizes the membrane and closes sodium channels. Local anesthetics attach themselves to the cell membrane and decrease the permeability of the nerve membran to the flow of sodium ions, blocking nerve conduction

Front 51

True/False
A rapid rate of injection will increase the rate of absorption at the injection site, thereby decreasing local anesthetic blood levels

Back 51

False
- the faster the rate of injection is, the less the local area can accept the volume injected

Front 52

The major advantage of amide local anesthetics over esters is:
A) cost
B) Ease of delivery
C) lack of allergenicity
D) longer duration

Back 52

C) lack of allergenicity
- Esters have a much greater allergic potential than amides

Front 53

Which of the following local anesthetics would be indicated for a lengthy dental procedure as a result of it long duration of action?
a) Prilocaine 4% with 1:200,000 epinephrine
b) Lidocaine 2% with 1:100,000 epinephrine
c) mepivicaine 3% plain
d) Articaine 4% with 1:100,000 epinephrine
e) Bupivacaine 0.5% with 1:200,000 epinephrine

Back 53

e) Bupivacaine 0.5% with 1:200,000 epinephrine
- bupivacaine has a greatly prolonged duration of action and is indicated in lengthy dental procedures when pulpal anesthesia of greater than 1 1/2 hours