Deck 3: Pharmacology of Local Anesthetic Agents

Question 1

Tachyphylaxis is a term used to describe what phenomenon?

A) An increased tolerance to a drug that is administered repeatedly.
B) If the dental procedure lasts longer than the duration of the anesthetic and the mantel and core fibers have fully recovered,the reinjection of local anesthetic will be ineffective.
C) Once the mantel fibers return to function,the patient experiences pain,yet administration of anesthetic does not alleviate the pain.
D) All options listed

Answer 1

All options listed

Question 2

Which component of the local anesthetic molecule improves the lipid solubility,facilitating the penetration of the anesthetic through the lipid-rich membrane where the receptor sites are located?

A) Hydrophilic amino group
B) Intermediate hydrocarbon ester or amide chain
C) Lipophilic aromatic ring
D) All options listed

Answer 2

Lipophilic aromatic ring

Question 3

What characteristic of local anesthetic drugs determines the speed of nerve recovery?

A) The concentration of the local anesthetic
B) The degree of lipid solubility
C) The degree of protein binding
D) The nonnervous tissue diffusibility

Answer 3

The degree of protein binding

Question 4

The most potent local anesthetic is bupivacaine,which has the greatest degree of lipid solubility.

Question 5

Dissociation constant refers to which of the following descriptions?

A) Determines the portion of administered anesthetic dose in the lipid-soluble state (RN)
B) Determines the onset of anesthetic action as the increase of molecules crossing the nerve membrane decreases the time of the anesthetic's onset
C) The pH at which 50% of the molecules exist in the lipid-soluble form and 50% in the water-soluble form
D) All options listed

Question 6

The rate of systemic absorption of local anesthetics depends on the total dose,concentration,route of administration,vascularity of tissues,and presence or absence of a vasoconstrictor.

Question 7

Intravascular injections significantly increase the possibility of an overdose.

Question 8

Local anesthetics easily cross the blood-brain barrier.

Question 9

Which component of the local anesthetic molecule renders the molecule water soluble?

A) Hydrophilic amino group
B) Intermediate hydrocarbon ester or amide chain
C) Lipophilic aromatic ring
D) All options listed

Question 10

What does the specific protein receptor theory of the action of local anesthetics suggest?

A) The specific protein receptor theory suggests that anesthetics that are highly lipid soluble cause the lipoprotein matrix of the nerve membrane to expand,narrowing the sodium channels,thus preventing depolarization.
B) The method by which the impulses travel down the length of the nerve affects whether nodes of Ranvier are stimulated or not.
C) Displaced Ca⁺⁺ and local anesthetic drugs compete to bind to receptor sites within the ion channels of cell membranes.
D) All options listed.

Question 11

If more anesthetic is needed for a procedure,it is important to reinject the anesthetic after the mantel fibers have fully recovered.

Question 12

Why is protein binding an important characteristic of local anesthetic drugs?

A) Increased protein binding allows more cations (RNH⁺)to bind to the receptor sites within the sodium channels,prolonging the presence of anesthetic at the site of action.
B) Increased protein binding allows more RN molecules to bind to the receptor sites within the sodium channels,prolonging the presence of anesthetic at the site of action.
C) Decreased protein binding allows more cations (RNH⁺)to bind to the receptor sites within the sodium channels,prolonging the presence of anesthetic at the site of action.
D) Decreased protein binding allows more RN molecules to bind to the receptor sites within the sodium channels,prolonging the presence of anesthetic at the site of action.

Question 13

What is the significant clinical difference between esters and amides?

A) Potential for allergic reactions
B) Cross-hypersensitivity
C) Lipid solubility
D) Drug potency

Question 14

Prilocaine is biotransformed in the liver only.

Question 15

What does the membrane expansion theory of the action of local anesthetics suggest?

A) Anesthetics that are highly hydrophilic cause the matrix of the nerve membrane to expand,narrowing the sodium channels,thus preventing depolarization.
B) Anesthetics that are highly lipid soluble cause the lipoprotein matrix of the nerve membrane to expand,narrowing the sodium channels,thus preventing depolarization.
C) Anesthetics cause the sodium channels to expand,thus allowing the increase in protein binding within the channels.
D) All options listed

Question 16

The speed of recovery from local anesthetic is determined by the degree of binding to the receptor site of each anesthetic.

Question 17

Local anesthetics affect the CNS and CVS after biotransformation.

Question 18

The higher the pK_a of an anesthetic,the faster the onset of action.

Question 19

Why is lipid solubility an important characteristic of local anesthetic drugs?

A) A greater lipid solubility enhances the diffusion of the anesthetic drug through the nerve.
B) A greater lipid solubility indicates a higher potency of the anesthetic drug.
C) A greater lipid solubility allows for a lower effective dose of the local anesthetic drug.
D) All options listed.

Question 20

Local anesthetics are vasoconstrictors and decrease the absorption of the drug by the blood.

Question 21

What is another name for the elimination of the local anesthetic from the blood and tissues?

A) Tachyphylaxis
B) Dissociation constant
C) Half-life
D) Distribution barriers

Question 22

What factor/factors influence(s)the duration of the effects of local anesthetics?

A) Degree of protein binding
B) Vascularity of injection site
C) Addition or absence of a vasoconstrictor
D) All options listed

Question 23

Anesthetic recovery is a slower process than induction because the anesthetic binds to the receptor site in the sodium channel,releasing the anesthetic slowly into the systemic circulation.

A) Both the statement and the reason are correct and related.
B) Both the statement and reason are correct but NOT related.
C) The statement is correct,but the reason is NOT.
D) The statement is NOT correct,but the reason is correct.
E) NEITHER the statement NOR the reason is correct.

Question 24

Which is the primary factor that determines the onset of action?

A) pH of the tissues
B) pK_a of the anesthetic agent
C) Administrative site
D) Anesthetic agent
E) None of the above

Question 25

Adding vasoconstrictor to local anesthetics can result in reduced systemic toxicity and increased duration of anesthetic because the vasoconstrictor reduces the rate of absorption.

A) Both the statement and reason are correct and related.
B) Both the statement and reason are correct but NOT related.
C) The statement is correct,but the reason is NOT.
D) The statement is NOT correct,but the reason is correct.
E) NEITHER the statement NOR the reason is correct.

Question 26

Which anesthetic drug has a short half-life of 45 minutes and is the least toxic of the anesthetics?

A) Articaine
B) Lidocaine
C) Mepivacaine
D) Prilocaine

Question 27

The time interval between the initial deposition of the anesthetic solution at the nerve site and complete conduction blockade is referred to as the:

A) Absolute refractory period
B) Relative refractory period
C) Induction time
D) Half-life
E) None of the above

Question 28

After absorption of the local anesthetics into the bloodstream,they are distributed throughout the body to all tissues.Highly vascular organs such as the brain,heart,liver,kidneys,and lungs have higher concentrations of anesthetics

A) Both statements are true.
B) Both statements are false.
C) The first statement is true;the second statement is false.
D) The first statement is false;the second statement is true.

Question 29

Ester local anesthetics have a high probability of producing an allergic reaction compared to amide local anesthetics.A patient who has an allergic reaction to one ester agent is likely to experience hypersensitivity to all ester anesthetics.

A) Both statements are true.
B) Both statements are false.
C) The first statement is true;the second statement is false.
D) The first statement is false;the second statement is true.

Question 30

Which part of the chemical structure of a local anesthetic determines the pattern of biotransformation of the anesthetic?

A) Lipophilic part
B) Hydrophilic part
C) Intermediate chain
D) All options listed

Question 31

Esters,benzocaine,tetracaine,and procaine are hydrolyzed in the plasma by the enzyme pseudocholinesterase and by liver esterases.Procaine is metabolized to PABA and is the major metabolic by-product responsible for allergic reactions.

A) Both statements are true.
B) Both statements are false.
C) The first statement is true;the second statement is false.
D) The first statement is false;the second statement is true.

Question 32

What is the inability to hydrolyze ester local anesthetics and other chemically related drugs called?

A) Atypical pseudocholinesterase
B) Low hepatic dysfunction
C) Para-aminobenzoic acid intolerance
D) None of the above

Question 33

Considering Sam's health history,what anesthetic drug may have been a better choice?

A) Procaine
B) Articaine with epinephrine
C) Lidocaine
D) Mepivacaine

Question 34

Reflecting on your experience with Sam,what other factors may contribute to an incident similar to Sam's?

A) The use of topical anesthetics plus intravascular injections
B) An injection that is administered too rapidly
C) The perio infection and inflammation
D) All options listed

Question 35

Which of the following is a major route of delivery of local anesthetic drugs?

A) Topical
B) Intravenous
C) Inhalation
D) All options listed

Question 36

Why do you think Sam's blood pressure decreased from the beginning of the appointment?

A) Sam became more comfortable during the appointment.
B) Symptoms of a CNS and CVS overdose are biphasic.
C) Symptoms of a possible overdose change from a stimulation phase to a depression phase.
D) All options listed

Question 37

What factor/factors determine the severity of an overdose reaction to local anesthetic?

A) Degree of drop in blood pressure
B) Time lapse between the administering of the local anesthetic to the overdose
C) Number of symptoms patient experiences
D) All options listed

Question 38

The liver is the organ responsible for the entire metabolic process of most amides.The rate of biotransformation is faster in patients with significant liver dysfunction.

A) Both statements are true.
B) Both statements are false.
C) The first statement is true;the second statement is false.
D) The first statement is false;the second statement is true.

Question 39

Based on Sam's physical symptoms,what should you consider?

A) Sam is extremely relaxed,and his blood pressure medication is working.
B) Sam is extremely stressed.
C) Sam may be experiencing a mild overdose to the anesthetic.
D) Sam may be experiencing a cardiovascular crisis.