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Local Anesthesia > Anesthetic Agents Part 1 > Flashcards

Anesthetic Agents Part 1 Flashcards

1
Q

How do we classify local anesthetics?

A
  1. By their chemical structure
    - esters
    - amides
  2. Duration of pulpal and hard tissue anesthesia
    - short –> 20-40 minutes
    - intermediate –> up to 70 minutes
    - long –> up to 8 hours
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2
Q

In U.S. we only inject which LA

A

Amide local anesthetics in dentistry

- injectable ester LA are available in other countries

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3
Q

Where do we use ester anesthetics?

A

In topical anesthetics

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4
Q

What are the considerations for selecting a local anesthetic agent

A
  1. length of time for which pain control is necessary
  2. need for post-treatment pain control
  3. need for hemostasis
  4. presence of contraindications for a given drug
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5
Q

What factors affect both the depth and the duration of a drug’s action

A
  1. individual response to drug
  2. accuracy in drug administration
  3. status of the tissues (ph)
  4. anatomical variation
  5. type of injection (supraperiosteal/infiltration or block)
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6
Q

Describe the difference between a hyper-responder and hypo-responder to LA

A

Hyper - effect lasts beyond what is expect

Hypo - effect dissipates quickly

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7
Q

T or F, Hypo-response to LA is not attributed to biotransformation/elimination

A

True –> not related to clinical actions

- simply occurs because this is how this individual responds to this drug

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8
Q

T or F, Deposition further away from nerve provides lesser depth and duration

A

True - “deposition closer to nerve provides greater depth and duration”

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9
Q

How does inflammation affect depth and duration of anesthesia?

A

Inflammation, infection or pain usually decreases depth and anticipated duration of anesthesia

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10
Q

How does increased vascularity affect duration of anesthesia?

A

Increased vascularity at site of deposition results in more rapid absorption and decreased duration
- depth of anesthesia will be greater in less vascular regions

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11
Q

T or F, Smaller than usual volumes decrease duration

A

True

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12
Q

T or F, Larger than recommended doses increase duration

A

False, DO NOT increase duration

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13
Q

Which duration of drug is best suited for non-traumatic procedures

A

Drugs with short duration

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14
Q

Name the drugs with long duration

A

bupivacaine (.5%) (8-12 hour of soft tissue anesthesia)

prilocaine 4% with 1:200,000 epinephrine (5-8 hours of soft tissue anesthesia)

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15
Q

Name the drugs with short duration

A

mepivacaine 3%

prilocaine 4%

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16
Q

What agents do you select when need for hemostasis?

A

Select agents with 1:50,000 or 1:100,000 epinephrine

- infiltrate locally into the surgical site

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17
Q

how many different drugs should you have in your office

A

Have a minimum of 2 different drugs of varying duration of action

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18
Q

What was the first synthetic local anesthetic?

A

Procaine (ester) = Novocain

  • 1904
  • used until lidocaine was developed in 1940s
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19
Q

Novocain is widely known for what characteristic?

A

Produces the greatest vasodilation of all currently used local anesthetics

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20
Q

How fast is the onset of action for novocain

A

slow onset of action (high pKa)

  • no pulpal anesthesia
  • only 15-30 minutes of soft tissue anesthesia
  • half life of 6 minutes
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21
Q

how is novocain metabolized?

A

by plasma cholinesterase (like all esters)

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22
Q

What was added to procaine HCl to hasten its onset and to increase duration of action

A

Propoxycaine

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23
Q

T or F, Propoxycaine is often used alone but can be very toxic

A

False, never used alone, as it is very toxic = limited utility

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24
Q

What combination of esters was only combo in dental cartridge

A

Procaine HCl + propoxycaine

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25
Q

What was the first amide LA to be marketed?

A 
Lidocaine HCl (1948)
- replaced procaine as drug of choice for pain control
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26
Q

In comparison to procaine, lidocaine:

A
  1. Significantly more rapid onset of action (2-3 minutes)
  2. Produces more profound anesthesia
    • Twice as potent as procaine
  3. Has longer duration of action
  4. Has greater potency
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27
Q

T or F, Allergy to amide LA isn’t common

A

True, it is virtually non-existent

- this is an advantage of lidocaine (and all amides)

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28
Q

Metabolites of lidocaine HCl

A

monoethylglyceine and xylidide

- **Pharmacologically active and potentially toxic

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29
Q

Where are lidocaine metabolites metabolized and excreted?

A 
Metabolism = liver (1/3 drug undergoes hydrolysis)
Excretion = kidneys (
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30
Q

T or F, Lidocaine is more vasodilating than prilocaine or mepivacaine

A

True

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31
Q

Onset of action for lidocaine HCl

A

Rapid onset (2-3 minutes)

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32
Q

Effective dental concentration for lidocaine HCl

A

2%

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33
Q

Does lidocaine HCl have a topical anesthetic action/

A

Yes; available in concentrations ranging from 2% to 10% in ointments

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34
Q

Lidocaine HCl pregnancy category

A

B

- safe during lactation; does not enter breast milk

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35
Q

3 formulations of lidocaine

A
  1. lidocaine 2% (no vasoconstrictor) light blue
  2. lidocaine 2% with epi 1:50,000 (green)
  3. lidocaine 2% with epi 1:100,000 (red)
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36
Q

What is the usefulness of lidocaine 2% plain?

A

very limited because of its vasodilating properties

  • only 5-10 minutes of pulpal anesthesia
  • higher blood levels

**Few applications for use of this drug in clinical practice

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37
Q

T or F, duration and depth of anesthesia is greater for lidocaine 2% with epi 1:50,000 than with epi 1:100,000

A

False, they duration and depth is equivalent

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38
Q

which version of lidocaine is concentration of choice?

A
  • -> lidocaine 2% with epi 1:100,000 is preferred drug for most dental procedures (safer)
    • especially for hyper-responders, elderly, ASA III or IV cardiac risk
  • lidocaine 2% 1:50,000 is concentration of choice BUT poses risk in patient with heart disease.
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39
Q

Signs and symptoms of lidocaine toxicity

A

CNS stimulation followed by CNS depression

**First signs and symptoms of overdose may be drowsiness, leading to loss of consciousness and respiratory arrest

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40
Q

What specific properties does lidocaine possess outside of dental procedures?

A

Possess anticonvulsant properties

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41
Q

available versions of mepivacaine HCl?

A
  1. 3% mepivacaine HCl (no vasoconstrictor)

2. 2% mepivacaine HCl w/ levonordefrin 1:20,000

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42
Q

Mepivacaine is chemically similar to what other LA? Pharmacologically similar to what other LA?

A

Chemically: bupivacaine
Pharmacologically: lidocaine
- lacks duration of bupivacaine

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43
Q

Which LA is the weakest vasodilator of all injectable amide LA?

A

Mepivacaine HCl

- mild vasodilating properties = longer acting than other LA without vasoconstrictors

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44
Q

Indications for Mepivacaine?

A
  1. Short/minor procedures requiring neither lengthy or profound pulpal anesthesia
  2. Patients with contraindications to vasoconstrictor
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45
Q

Signs and symptoms of overdose of mepivacaine

A

Follow more classic presentation

  • CNS stimulation followed by depression
    • -> absence of CNS stimulation phase with immediate depression is rare
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46
Q

Potency of Mepivacaine HCl

A
  1. Twice as potent as procaine
  2. Equal to lidocaine and prilocaine
  3. 2/3 as potent as articaine
  4. 1/4 as potent as bupivacaine
47
Q

Mepivacaine is similar in toxicity to what?

A

articaine

lidocaine

48
Q

Metabolism and excretion of mepivacaine

A

Liver via hydroxylation and N-demethylation

Via kidneys = ~1-16% of dose excreted unchanged

49
Q

Why is it good to know that mepivacaine is the weakest vasodilator of all 5 injectable LA drugs in dental form?

A

Because it allows it to be used without a vasoconstrictor

50
Q

Onset of action for mepivacaine HCl

A

Rapid (1-2 minutes)

51
Q

Mepivacaine HCl pregnancy category

A

C

- Not known whether crosses into breast milk; use caution

52
Q

Pharmacologically, prilocaine is similar to what?

A

mepivacaine

53
Q

What is the risk found with prilocaine?

A

can reduce the blood’s oxygen carrying capability, which may lead to a specific type of anemia
- methemoglobinemia

54
Q

How does prilocaine differ from lidocaine and mepivacaine?

A

Chemical ring structure is different
Aromatic ring is linked to a secondary amine
- other amide LA are all linked to tertiary amines

55
Q

Metabolites of prilocaine

A

Orthotoluidine
N-propylalanine
**Carbon Dioxide is major end-product of biotransformation

56
Q

Which metabolic of prilocaine induces formation of methemoglobin

A

Orthotoluidine

57
Q

T or F, Lidocaine is metabolized much more rapidly and completely than prilocaine

A

False, Prilocaine is metabolized much more rapidly and completely than lidocaine

58
Q

Biotransformation of prilocaine takes place where?

A

Liver

- also in lungs and kidney**

59
Q

Prilocaine is excreted via?

A

Kidneys

***Renal clearance is faster than for all other amides

60
Q

How toxic is Prilocaine in comparison to comparable potent amides?

A

Less toxic systemically

- less toxic because it is removed from circulation faster

61
Q

Prilocaine is available in 2 formulations:

A

Prilocaine 4% (plain)

Prilocaine 4% w/ epi 1:200,000

62
Q

How useful is prilocaine 4% (plain)

A

Frequently able to provide anesthesia of equal duration seen with lidocaine or mepivacaine with vasoconstrictor

63
Q

How much of a vasodilator is prilocaine?

A

Weak vasodilator

- can get good clinical effects without a vasoconstrictor (not as weak as mepivacaine)

64
Q

Prilocaine 4% w/ epi 1:200,000 is good for what patients?

A

good for epinephrine-sensitive patients with the least concentrated dilution of epinephrine but still provides lengthy anesthesia

65
Q

Contraindications to prilocaine

A
  1. idiopathic or congenital methemoglobinemia
  2. hemoglobinopathies (sickle cell anemia)
  3. anemia
  4. cardiac or respiratory failure with hypoxia
  5. acetaminophen or phenacetin
66
Q

Potency of prilocaine

A
  1. twice as potent as procaine
  2. equal to lidocaine and mepivacaine
  3. 2/3 as potent as articaine
  4. 1/4 as potent as bupivacaine
67
Q

toxicity of prilocaine

A

half as toxic as lidocaine

68
Q

Describe the metabolism comparisons between prilocaine and lidocaine

A

Prilocaine is more rapid and complete biotransformation than lidocaine

69
Q

Place the vasodilating properties in order for procaine, lidocaine, mepivacaine and prilocaine

A
  1. mepivacaine (weakest)
  2. Prilocaine
  3. lidocaine 3. Articaine
  4. procaine
70
Q

topical anesthetic action for prilocaine

A

Only in combination with other drugs; 2.5% lidocaine + 2.5% prilocaine

71
Q

Prilocaine pregnancy category

A

B

- thought to enter into breast milk; use with caution

72
Q

Describe the ring structure for articaine

A

Amide

  • Thiophene ring (lipophilic) for aromatic ring
  • contains an ester side chain off ring structure
  • Sulfur atom within ring structure = eases passage through neural membrane = increased lipid solubility
73
Q

Where does biotransformation occur for articaine

A

Plasma (ester) and liver (amide)

74
Q

What makes the biotransformation of articaine different than other amide components?

A

Because of the ester component, this allows for rapid biotransformation = majority of drug is metabolized in plasma (approx. 90%)
- short half life… only 20 minutes (lidocaine = 90 minutes)

75
Q

Which LA has the most rapid onset of all five injectable amide LA?

A

Articaine

76
Q

T or F, Artisane is not effective without a vasoconstrictor

A

True

77
Q

Available formulations of articaine

A

articaine 4% with epinephrine 1:100,000

articaine 4% with epinephrine 1:200,000

78
Q

T or F, artisane presents less risk for systemic toxicity? why

A

True, because of its rapid metabolism and clearance

79
Q

T or F, multiple cases of methemoglobinemia have been reported with usual use of articaine in dentistry

A

False, NO cases

80
Q

Potency of articaine

A
  1. twice as potent as procaine
  2. 1/3 more potent than lidocaine, mepivacaine and prilocaine
  3. 1/3 as potent as bupivacaine
81
Q

metabolism for articaine

A 
amide = liver
ester = plasma (cholinesterase)
82
Q

Excretion for articaine

A

Kidneys (less than 2% is excreted unchanged)

83
Q

Pregnancy category or articaine

A

C

- may enter breast milk; use with caution

84
Q

2 primary indications for bupivacaine

A
  1. Lengthy dental procedures requiring pulpal anesthesia for longer than 90 minutes
  2. Management of post-operative pain
    • Need for post-op opioids is significantly reduced
85
Q

Describe onset for bupivacaine

A

For some it is normal as in other amides (2-4 minutes)

- **But for many, onset is delayed to 6-10 minutes

86
Q

Which amide LA has the slowest onset of all amide LA

A

bupivacaine

- due to high pKa

87
Q

T or F, bupivacaine is recommended for adult patients as well as younger patients including children and toddlers

A

False, NOT recommended for children and for patients at risk for self-injury

88
Q

Which amide LA is the most potent vasodilator of all injectable amide LA?

A

bupivacaine

- However it isn’t as potent as procaine (ester is most potent)

89
Q

Why is bupivacaine capable of producing prolonged anesthesia

A
  • due to strong receptor binding in sodium channels

- can last for up to 12 hours = LONGEST ACTING AMIDE LA

90
Q

bupivacaine will not be metabolized or cleared as quickly in what patients?

A

with compromised cardiovascular system

91
Q

Explain overdoses and their occurrence with bupivacaine

A

Overdoses are common
When overdose occurs, it is more severe and less easily reversed
- Cardiotoxic

92
Q

available form of bupivacaine

A

bupivacaine 0.5% with epinephrine 1:200,000

93
Q

describe metabolism & excretion of bupivacaine

A

M: Liver by amidases (slow)
E: Kidney

94
Q

What is the most toxic LA

A

bupivacaine

95
Q

Pregnancy category of bupivacaine

A

C

- may enter breast milk; use with caution

96
Q

Use of topical anesthetic is important for what reason?

A

atraumatic injection technique

- pre-injection numbing

97
Q

T or F, Concentration for the same drug applied topically is lower than what is used via injection

A

False, HIGHER

** Higher concentrations increase risk for toxicity

98
Q

T or F, LA are vasodilators = topical agents also contain vasoconstrictors

A

False, they do not contain vasoconstrictors

  • able to get absorbed
  • some quickly
99
Q

T or F, many injectable LA are ineffective as topical because the concentrations necessary to produce topical anesthesia are too high

A

True

- significantly increases risk for overdose and local tissue toxicity

100
Q

Which LA are NOT used topically

A 
Articaine
Mepivacaine
Prilocaine (only in combination topical anesthetics)
Procaine
Bupivacaine
101
Q

Topical anesthesia is effective only where?

A

on surface tissues (2-3 mm)

102
Q

Formulations for topical anesthestics

A

Ointments
gels
solutions
sprays

103
Q

Benzocaine has what ring structure

A

ester

104
Q

T or F, Benzocaine is not suitable for injection

A

True

105
Q

Why is dyclonine hydrochloride chemically unique?

A

Ketone

- excellent for patients with known sensitivities to other LA

106
Q

Potency of dyclonine hydrochloride is equal to that of what other LA

A

Cocaine

107
Q

Onset of action for dyclonine hydrochloride

A

slow (up to 10 minutes) but lasts for up to 1 hour

108
Q

Lidocaine is available in what 2 forms for topical application?

A
  1. lidocaine base

2. lidocaine hydrochloride

109
Q

Most potent of dental topical anesthetics

A

tetracaine hydrochloride

110
Q

Cetacaine contains what compounds?

A

benzocaine, butamben, and tetracaine

- contains 3 esters

111
Q

2 formulations of 2.5% lidocaine with 2.5% prilocaine

A
  1. EMLA = primarily used in medicine

2. Oraqix = specifically formulated for dentistry

112
Q

Characteristics of eutectic mixtures

A
  • Provide more rapid onset on skin
  • greater depth of topical penetration on both skin and mucous membranes
  • higher concentrations of base forms of drugs
113
Q

What eutectic mixture is used for intrapockets?

A

Oraqix

- applied into gingival pocket

Local Anesthesia (3 decks)

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