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Pharmocology > Chapter 9 > Flashcards

Chapter 9 Flashcards

(65 cards)

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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
The nonionized form is needed for?
to penetrate the nerve membrane
26
The ionized form is needed to?
Exert the blocking action by binding to the specific receptor site
27
Local anesthetics: Pharmacokinetics
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
The vasoconstrictor
Reduces the blood supply to the area Limits systemic absorption Reduces systemic toxicity
29
Local anesthetics: Absorptions
Mucous membranes or denuded surface = increased absorption | Absorption also determine by the proportion of the agent present in the free-base form (nonionized)
30
Local anesthetics: Distribution
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
Esters are hydrolyzed by
plasma pseudocholinesterases and liver esterases
32
Amides are metabolized by the
liver
33
Cimetidine (Tagamet)
reduces hepatic blood flow and may increase the systemic level of an amide
34
What is the function or pharmacologic effect of a local anesthetic?
Blocks the conduction of peripheral nerves | Produces an antiarrhythmic effect on the heart
35
Order of nerve function loss when losing local anesthetics
Autonomic (first) Pain (middle) Motor (last)
36
Pharmacologic effects
``` 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
Adverse reactions of local anesthetics
Directly related to the plasma level of the drug
38
These peopl are more prone to adverse or toxic effects of local anesthetics
Children, elderly, and debilitated
39
Adverse reaction toxicity affecting the CNS system
CNS stimulation | CNS depression
40
Adverse reaction toxicity affecting cardiovascular system
Myocardial depression Cardiac arrest with peripheral vasodilation Usual concentrations not expected to result in any of these adverse reactions
41
Adverse reaction local effects
Result of injection technique Result of administration of an excessive volume too quickly Hematoma
42
An inherited disease that is transmitted as an autosomal-dominant gene
Malignant hyperthermia
43
Malignant hyperthermia
Acute rise in calcium leading to muscular rigidity, metabolic acidosis, and extremely high fever; mortality rate 50%
44
dantrolene (Dantrium)
Used to treat malignant hyperthermia
45
Lidocaine and Prilocaine FDA pregnancy category
B
46
Mepivacaine, Articaine, Bupivacaine FDA pregnancy category
C
47
Have a much higher allergic potential
Esters
48
Sulfite
a component of local anesthetics with a vasoconstrictor. | it serves as an antioxidant but may be associated with allergic reactions
49
Vasoconstrictor - Epinephrine
Retards absorption, reduce systemic toxicity, and prolong duration of action
50
Most commonly used dental anesthetic
Lidocaine
51
2% lidocaine with 1:100,000 epinephrine
provides 1-1.5 hours of pulpal anesthesia and 3-4 hours of soft tissue anesthesia
52
Not effective topically
Mepivacaine (Carbocaine, Polocaine, Isocaine)
53
Prilocaine
Toludine derivitave | Less potent and less toxic then lidocaine
54
Bupivacaine
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
Articaine
Derived from thiophene Greater lipid solubility Hydrolyzed by plasma esterase Metabolized mainly in blood
56
in a 1.7 ml cartidge unlike the more common 1.8 ml dental cartridge
Articaine (Septocaine)
57
Commonly used ester topically
Benzocaine
58
Procaine (Novocain)
Not used in dentristy
59
Vasoconstrictors
Prolong the duration of action Increase the depth of anesthesia Delay systemic absorption Reduce the toxic effect in the systemic circulation
60
Members of the autonomic nervous system drugs called the sympathomimetics or adrenergic agonists
vasoconstrictors
61
Tricyclic antidepressants
Administration of epinephrine may produce an exaggerated increase in pressor response
62
Nonselective B-blockers
Administration of epinephrine may produce hypertension and reflex bradycardia
63
Epinephrine cardiac dose
0.04 mg
64
Epinephrine healthy patient
0.2 mg
65
Second most commonly used topical anesthetic
Lidocaine

Pharmocology (12 decks)

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