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Pharmocology > Chapter 9 > Flashcards

Chapter 9 Flashcards

1
Q

Most often used drug in dentistry

A

Local anesthetics

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2
Q

What was the first local anesthetic

A

Cocaine

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3
Q

Properties of the ideal local anesthetic

A
  • Potent local anesthesia
  • Reversible local anesthesia
  • Abscence of local reactions
  • Abscence of allergic reactions
  • Rapid onset
  • Satisfactory onset
  • Adequate tissue penetration
  • Low cost
  • stability in solution
  • sterilizatioln in autoclave
  • ease of metabolism and excretion
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4
Q

2 major groups of local anesthetics

A

Esters
Amides
Other —> minor group

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5
Q

Where are esters metabolized

A

in the plasma

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6
Q

Where are amides metabolized

A

in the liver

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7
Q

Components of local anesthetic

A
  • Aromatic nucleus - lipophilic ( lipid soluble )
  • Linkage ( ester or amide, followed by aliphatic chain )
  • Amino group - hydrophilic ( water soluble )
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8
Q

Why is it important to know if a local anesthetic is an ester or amide?

A

Potential allergic reactions

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9
Q

What if a person is allergic to one agent in a group of anesthetics?

A

They are likely to be alergic to another agent in that group

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10
Q

Cross hypersensitivity between the amides and esters

A

is unlikely

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11
Q

Cation

A

Ion with a positve charge

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12
Q

Anion

A

Ion with a negative charge

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13
Q

Resting nerve

A

Has a large number of positive ions ( cations ) on the outside and a large number of negative ions ( anions ) on the inside
Membrane potentions of -90 mV to -60 mV charge

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14
Q

What happens when an action potention goes from -90 mV to 40 mV

A

It triggers the efflux of potassium until a resting action potential of -90 mV is reestablished

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15
Q

What happens when local anesthetics bind to receptors in the nerve membrane and blocks conduction of the nerve impulse by decreasing the permeability of the cell membrane to sodium ions

A

Increases the threshold of excitability and prevents the propagation of the action potential

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16
Q

pH of local anesthetics without vasoconstrictors

A

range in pH from 5 to greater than 6

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17
Q

pH of local anesthetics with vasocontrictors

A

range in pH from 3 yo 5 because of the addition of sodium bisulfate

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18
Q

Local anesthetics occur in equilibrium between 2 forms

A

A free base and a salt

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19
Q

Free base

A 
Viscid liquids or amorphous solids
Fat soluble
Unstable
Alkaline
Uncharged, nonionized
Penetrates nerve tissue
Form present in tissue ( pH 7.4 )
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20
Q

Salt

A 
Crystaline solids
Water soluble
Stable
Acidic
Charged, cation ( ionized )
Active form at side of actions
Form present in dental cartridge ( pH 4.5 - 6.0 )
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21
Q

Proportion of drug in each form is determined by

A

pK

pH of the environment

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22
Q

pK

A

The pH at which half is in each form ( base and acid equally)

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23
Q

If there is a dental infection or abscess in the area to be injected will anesthesia be more difficult to achieve?

A

Yes

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24
Q

The area prior to injection is more acidic than normal with a lower pH with what?

A

Dental infection or abscess

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25
Q

The nonionized form is needed for?

A

to penetrate the nerve membrane

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26
Q

The ionized form is needed to?

A

Exert the blocking action by binding to the specific receptor site

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27
Q

Local anesthetics: Pharmacokinetics

A

Absorptions depends on its route
Rate of absorption depends on vascularity of the tissues
Degree of inflammation present
Vasodilating properties of the local anesthetic agent
Presence of heat
Use of massage
The vasoconstrictor

28
Q

The vasoconstrictor

A

Reduces the blood supply to the area
Limits systemic absorption
Reduces systemic toxicity

29
Q

Local anesthetics: Absorptions

A

Mucous membranes or denuded surface = increased absorption

Absorption also determine by the proportion of the agent present in the free-base form (nonionized)

30
Q

Local anesthetics: Distribution

A

Highly vascular organs have higher concentrations of anesthetics
Local anesthetics cross the placenta and blood-brain barrier
Lipid solubility affects the potency of the agent

31
Q

Esters are hydrolyzed by

A

plasma pseudocholinesterases and liver esterases

32
Q

Amides are metabolized by the

A

liver

33
Q

Cimetidine (Tagamet)

A

reduces hepatic blood flow and may increase the systemic level of an amide

34
Q

What is the function or pharmacologic effect of a local anesthetic?

A

Blocks the conduction of peripheral nerves

Produces an antiarrhythmic effect on the heart

35
Q

Order of nerve function loss when losing local anesthetics

A

Autonomic (first)
Pain (middle)
Motor (last)

36
Q

Pharmacologic effects

A 
Direct effect on cardiac muscles
Block cardiac sodium channels
Depress abnormal cardiac pacemaker activity, excitability, and conduction
Depress strength of cardiac contraction
Produce arteriolar dilation
Treatment of arrhythmias
37
Q

Adverse reactions of local anesthetics

A

Directly related to the plasma level of the drug

38
Q

These peopl are more prone to adverse or toxic effects of local anesthetics

A

Children, elderly, and debilitated

39
Q

Adverse reaction toxicity affecting the CNS system

A

CNS stimulation

CNS depression

40
Q

Adverse reaction toxicity affecting cardiovascular system

A

Myocardial depression
Cardiac arrest with peripheral vasodilation
Usual concentrations not expected to result in any of these adverse reactions

41
Q

Adverse reaction local effects

A

Result of injection technique
Result of administration of an excessive volume too quickly
Hematoma

42
Q

An inherited disease that is transmitted as an autosomal-dominant gene

A

Malignant hyperthermia

43
Q

Malignant hyperthermia

A

Acute rise in calcium leading to muscular rigidity, metabolic acidosis, and extremely high fever; mortality rate 50%

44
Q

dantrolene (Dantrium)

A

Used to treat malignant hyperthermia

45
Q

Lidocaine and Prilocaine FDA pregnancy category

A

B

46
Q

Mepivacaine, Articaine, Bupivacaine FDA pregnancy category

A

C

47
Q

Have a much higher allergic potential

A

Esters

48
Q

Sulfite

A

a component of local anesthetics with a vasoconstrictor.

it serves as an antioxidant but may be associated with allergic reactions

49
Q

Vasoconstrictor - Epinephrine

A

Retards absorption, reduce systemic toxicity, and prolong duration of action

50
Q

Most commonly used dental anesthetic

A

Lidocaine

51
Q

2% lidocaine with 1:100,000 epinephrine

A

provides 1-1.5 hours of pulpal anesthesia and 3-4 hours of soft tissue anesthesia

52
Q

Not effective topically

A

Mepivacaine (Carbocaine, Polocaine, Isocaine)

53
Q

Prilocaine

A

Toludine derivitave

Less potent and less toxic then lidocaine

54
Q

Bupivacaine

A

More potent and toxic the lidocaine and mepivacaine
Prolonged duration of action, useful for dental surgery
Should not be used in children or mentally challenged patients

55
Q

Articaine

A

Derived from thiophene
Greater lipid solubility
Hydrolyzed by plasma esterase
Metabolized mainly in blood

56
Q

in a 1.7 ml cartidge unlike the more common 1.8 ml dental cartridge

A

Articaine (Septocaine)

57
Q

Commonly used ester topically

A

Benzocaine

58
Q

Procaine (Novocain)

A

Not used in dentristy

59
Q

Vasoconstrictors

A

Prolong the duration of action
Increase the depth of anesthesia
Delay systemic absorption
Reduce the toxic effect in the systemic circulation

60
Q

Members of the autonomic nervous system drugs called the sympathomimetics or adrenergic agonists

A

vasoconstrictors

61
Q

Tricyclic antidepressants

A

Administration of epinephrine may produce an exaggerated increase in pressor response

62
Q

Nonselective B-blockers

A

Administration of epinephrine may produce hypertension and reflex bradycardia

63
Q

Epinephrine cardiac dose

A

0.04 mg

64
Q

Epinephrine healthy patient

A

0.2 mg

65
Q

Second most commonly used topical anesthetic

A

Lidocaine

Pharmocology (12 decks)

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