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A Baseline Pharma > Local Anesthetics > Flashcards

Local Anesthetics Flashcards

1
Q

How many types of Local Anesthetics are there?

A) Esters

B) Amides

C) Both Esters and Amides

D) Neither

A

C) Esters and Amides

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2
Q

What is the primary mechanism of action (MOA) for local anesthetics?

A) Inhibition of K+ channels

B) Binding to GPCR receptors

C) Blocking voltage-gated Na+ channels

D) Activating Ca2+ channels

A

C) Blocking voltage-gated Na+ channels during the activated and/or inactivated state.

Blocks/inhibits Na+ current to ↓excitability of neuronal, cardiac, or CNS tissue.

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3
Q

Local anesthetics can also bind to which of the following channels or receptors besides Na+ channels?

A) K+ and Ca2+ channels, and GPCR receptors

B) Only Ca2+ channels

C) Only K+ channels

D) Only GPCR receptors

A

A) K+ and Ca2+ channels, and GPCR receptors

Blocks/inhibits Na+ current to ↓excitability of neuronal, cardiac, or CNS tissue.

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4
Q

What is the goal for the Minimum Effective Concentration (MEC) of a local anesthetic?

A) To block 1-2 nodes of Ranvier

B) To block 3-4 nodes of Ranvier

C) To block 2-3 nodes of Ranvier

D) To block 4-5 nodes of Ranvier

A

C) To block 2-3 nodes of Ranvier

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5
Q

Why are local anesthetics often mixed with epinephrine?

A) To increase their pH

B) To enhance their lipid solubility

C) To reduce their intrinsic vasodilatory effects

D) To decrease their potency

A

C) To reduce their intrinsic vasodilatory effects

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6
Q

What is the effect of having a local anesthetic with a pKa that is closest to the physiologic pH?

A) Slower onset of action

B) Faster onset of action

C) Increased ionization of the drug

D) Decreased lipid solubility

A

B) Faster onset of action

LA are Weak bases with pKa above physiologic pH

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7
Q

What is the primary determinant of the potency of a local anesthetic?

A) Its pKa

B) Its pH

C) Its lipid solubility

D) Its rate of metabolism

A

C) Its lipid solubility

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8
Q

How does acidosis affect the efficacy of local anesthetics?

A) It decreases the ionized fraction of the drug, increasing efficacy

B) It increases the ionized fraction of the drug, decreasing efficacy

C) It has no effect on the drug’s efficacy

D) It improves lipid solubility, enhancing efficacy

A

B) It increases the ionized fraction of the drug, decreasing efficacy

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9
Q

Local anesthetics are classified as weak bases. How does this influence their behavior in physiological conditions?

A) They remain mostly ionized in alkaline conditions

B) They are less effective in acidic conditions

C) They are more potent in acidic environments

D) They are rapidly metabolized in alkaline conditions

A

Answer: B) They are less effective in acidic conditions

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10
Q

How are ester-type local anesthetics metabolized and eliminated from the body?

A) Metabolized by hepatic enzymes and excreted in feces

B) Reduced by plasma cholinesterases and excreted in urine

C) Metabolized in the liver and excreted in bile

D) Broken down in the kidneys and excreted in urine

A

B) Reduced by plasma cholinesterases and excreted in urine

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10
Q

Which type of local anesthetic is primarily eliminated by hepatic metabolism?

A) Esters

B) Amides

C) Both Esters and Amides

D) Neither

A

B) Amides

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10
Q

Which type of local anesthetic is primarily metabolized by microsomal enzymes in the liver?

A) Esters

B) Amides

C) Both Amides and Esters

D) Neither

A

B) Amides

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11
Q

Which ester-type local anesthetic is metabolized in the liver instead of by plasma cholinesterase?

A) Procaine

B) Tetracaine

C) Cocaine

D) Chloroprocaine

A

C) Cocaine

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11
Q

Which factors most significantly influence the rate of clearance of local anesthetics?

A) Dose of medication and frequency of administration

B) Rate of tissue distribution, cardiac output, and protein binding

C) Route of administration and duration of action

D) pH of the local environment and rate of metabolism

A

B) Rate of tissue distribution, cardiac output, and protein binding

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12
Q

Which type of local anesthetic undergoes hydrolysis primarily by plasma cholinesterase?

A) Amides

B) Esters

C) Both Amides and Esters

D) Neither

A

B) Esters

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12
Q

Which amide local anesthetic is metabolized the most rapidly?

A) Bupivacaine

B) Mepivacaine

C) Prilocaine

D) Lidocaine

A

C) Prilocaine

Prilocaine (most rapid) > lidocaine and mepivacaine (intermediate) > etidocaine, bupivacaine and ropivacaine (slowest).

Amides are slower than esters overall.

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13
Q

Which part of the sodium channel do local anesthetics bind to?

A) L-gate

B) N-gate

C) H-gate (α subunit)

D) M-gate

A

C) H-gate (α subunit)

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14
Q

How do local anesthetics affect the sodium channel’s function?

A) They increase the rate of sodium channel activation

B) They block sodium ion channels to inhibit neuronal depolarization

C) They enhance the inactivation of sodium channels

D) They facilitate rapid repolarization of the channel

A

B) They block sodium ion channels to inhibit neuronal depolarization

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15
Q

What is the primary effect of local anesthetics binding to the H-gate of the sodium channel?

A) Enhancement of depolarization

B) Prevention of repolarization

C) Prevention of depolarization during inactivated and activated states

D) Facilitation of sodium ion influx

A

Answer: C) Prevention of depolarization during inactivated and activated states

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16
Q

What is a common cause of local anesthetic systemic toxicity (LAST)?

A) Overdosing on oral medication

B) Excess plasma concentration due to vascular injection

C) Excessive topical application

D) Rapid intravenous infusion

A

Answer: B) Excess plasma concentration due to vascular injection

17
Q

Which of the following is a primary symptom of LAST?

A) Severe abdominal pain

B) Seizure-like activity and cardiovascular collapse

C) Severe headache and nausea

D) Acute kidney failure

A

B) Seizure-like activity and cardiovascular collapse

18
Q

Which intervention is considered a last resort for LAST if other treatments are ineffective?

A) Dialysis

B) Cardiopulmonary bypass (CPB)

C) Intravenous fluids

D) Hyperbaric oxygen therapy

A

Answer: B) Cardiopulmonary bypass (CPB)

19
Q

What is the first-line treatment for local anesthetic systemic toxicity (LAST)?

A) Intravenous corticosteroids

B) Sodium bicarbonate

C) Lipid emulsion therapy and ACLS aspects.

D) Antihistamines

A

C) Lipid emulsion therapy and ACLS aspects

20
Q

What are some common CNS effects of local anesthetic systemic toxicity?

A) Bradycardia and hypotension

B) Restlessness, circumoral numbness, vertigo, tinnitus, and difficulty focusing

C) Severe dehydration and renal failure

D) Hyperglycemia and liver dysfunction

A

B) Restlessness, circumoral numbness, vertigo, tinnitus, and difficulty focusing

21
Q

How do local anesthetics affect the cardiovascular system?

A) They increase conduction and automaticity

B) They cause depression of conduction and automaticity, leading to slowed conduction and prolonged PR interval and QRS complex

C) They enhance calcium and potassium channel activity

D) They stimulate cAMP production

A

Answer: B) They cause depression of conduction and automaticity, leading to slowed conduction and prolonged PR interval and QRS complex

22
Q

Which ions and channels are affected by local anesthetics in the cardiovascular system?

A) Na+ and Cl- channels, and they increase cAMP production

B) Ca2+ and K+ channels, and they may inhibit cAMP production

C) Only Na+ channels, with no effect on cAMP production

D) Only Ca2+ channels, with enhanced cAMP production

A

B) Ca2+ and K+ channels, and they may inhibit cAMP production

23
Q

Which local anesthetics are most commonly associated with allergic reactions?

A) Amides

B) Esters

C) Both Amides and Esters

D) Neither

A

Answer: B) Esters

24
Q

What is the primary cause of allergic reactions to local anesthetics?

A) High systemic concentration

B) Metabolites related to para-aminobenzoic acid (PABA) and methylparaben preservatives

C) Interaction with other medications

D) Rapid metabolism in the liver

A

Answer: B) Metabolites related to para-aminobenzoic acid (PABA) and methylparaben preservatives

25
Q

How do local anesthetics affect the cardiac action potential?

A) They increase the maximal depolarization rate (Vmax)

B) They have no effect on Vmax

C) They depress the maximal depolarization rate (Vmax) by virtue of their ability to inhibit Na+ influx via Na+ channels.

D) They enhance Na+ influx to increase Vmax

A

C) They depress the maximal depolarization rate (Vmax) by virtue of their ability to inhibit Na+ influx via Na+ channels.

26
Q

What is Cauda Equina Syndrome (CES) primarily caused by?

A) Localized injury to the lumbar spine

B) Diffuse injury across the lumbosacral plexus

C) Infections of the spinal cord

D) Hemorrhage in the spinal canal

A

B) Diffuse injury across the lumbosacral plexus

26
Q

When do Transient Neurologic Symptoms (TNS) usually appear after recovery from spinal anesthesia?

A) Immediately after the procedure

B) 1-2 hours after recovery

C) 6-36 hours after recovery

D) 48-72 hours after recovery

A

C) 6-36 hours after recovery

26
Q

What are Transient Neurologic Symptoms (TNS) typically characterized by?

A) Severe abdominal pain

B) Moderate to severe lower back pain, buttocks, and posterior thighs

C) Acute headache and neck stiffness

D) Numbness in the upper extremities

A

B) Moderate to severe lower back pain, buttocks, and posterior thighs

27
Q

Which local anesthetic is most commonly associated with Transient Neurologic Symptoms (TNS)?

A) Bupivacaine

B) Ropivacaine

C) Hyperbaric 5% lidocaine

D) Mepivacaine

A

C) Hyperbaric 5% lidocaine

28
Q

Which symptoms are commonly associated with Cauda Equina Syndrome (CES)?

A) Headache and dizziness

B) Sensory anesthesia, bowel and bladder sphincter dysfunction, and paraplegia

C) Visual disturbances and tinnitus

D) Upper extremity numbness and weakness

A

B) Sensory anesthesia, bowel and bladder sphincter dysfunction, and paraplegia

28
Q

Question 1:
What is the primary symptom of Anterior Spinal Artery Syndrome?

A) Upper extremity weakness

B) Lower extremity paresis with variable sensory deficit

C) Severe headache

D) Bowel and bladder dysfunction

A

B) Lower extremity paresis with variable sensory deficit that is usually diagnosed as the neural blockade resolves

29
Q

Which local anesthetic is most commonly associated with Cauda Equina Syndrome (CES)?

A) Bupivacaine

B) Ropivacaine

C) Hyperbaric 5% lidocaine

D) Mepivacaine

A

C) Hyperbaric 5% lidocaine

30
Q

What is a common cause of Anterior Spinal Artery Syndrome?

A) Excessive sedation

B) Addition of epinephrine (vasoconstriction)

C) High doses of local anesthetic

D) Infection at the injection site

A

B) Addition of epinephrine (vasoconstriction)

30
Q

What are potential risk factors for developing Anterior Spinal Artery Syndrome?

A) Young age and good cardiovascular health

B) Advanced age and peripheral vascular disease

C) High physical activity levels

D) Recent surgery in the upper extremities

A

B) Advanced age and peripheral vascular disease

31
Q

What causes methemoglobinemia?

A) Accumulation of carbon monoxide in hemoglobin

B) Oxidation of hemoglobin to methemoglobin more rapidly than its reduction back to hemoglobin

C) Deficiency in vitamin B12

D) Excessive iron in the bloodstream

A

B) Oxidation of hemoglobin to methemoglobin more rapidly than its reduction back to hemoglobin

32
Q

What is the primary treatment for methemoglobinemia?

A) Sodium bicarbonate

B) Oxygen therapy

C) Methylene blue 1-2 mg/kg IV over 5 minutes (not to exceed 7-8 mg/kg)

D) Intravenous fluids

A

C) Methylene blue 1-2 mg/kg IV over 5 minutes (not to exceed 7-8 mg/kg)

32
Q

How does lidocaine affect the ventilatory response to hypoxia?

A) It enhances the ventilatory response to hypoxia

B) It has no effect on the ventilatory response to hypoxia

C) It depresses the ventilatory response to hypoxia

D) It increases the sensitivity of the hypoxic drive

A

C) It depresses the ventilatory response to hypoxia

32
Q

At what methemoglobin level does central cyanosis typically occur?

A) MetHgb > 5%

B) MetHgb > 10%

C) MetHgb > 15%

D) MetHgb > 20%

A

C) MetHgb > 15%

33
Q

What is the effect of methemoglobin on oxygen binding?

A) It enhances oxygen binding to hemoglobin

B) It prevents hemoglobin from binding oxygen

C) It has no effect on oxygen binding

D) It increases the release of oxygen to tissues

A

B) It prevents hemoglobin from binding oxygen

33
Q

Why might patients with CO2 retention be at risk for ventilatory failure when lidocaine is administered for treatment of cardiac dysrhythmias?

A) Lidocaine enhances CO2 retention

B) Lidocaine increases ventilatory drive, leading to hyperventilation

C) Lidocaine depresses the ventilatory response to hypoxemia, which is crucial for patients whose ventilation depends on hypoxic drive

D) Lidocaine stimulates respiratory centers in the brain

A

C) Lidocaine depresses the ventilatory response to hypoxemia, which is crucial for patients whose ventilation depends on hypoxic drive

Patients with CO2 retention whose resting ventilation depends on hypoxic drive may be at risk for ventilatory failure when lidocaine is administered for treatment of cardiac dysrhythmias.

33
Q

Why might a pulse oximeter show a reading of 85% in a patient with methemoglobinemia?

A) Due to a malfunction in the pulse oximeter

B) Due to the oxidation of iron in hemoglobin, which affects the accuracy of the pulse oximeter

C) Because of low blood pressure

D) Because of an excess of oxygen in the bloodstream

A

B) Due to the oxidation of iron in hemoglobin, which affects the accuracy of the pulse oximeter

Tx: methylene blue.

33
Q

Which local anesthetics are commonly associated with methemoglobinemia?

A) Bupivacaine and ropivacaine

B) Prilocaine, benzocaine, and lidocaine

C) Mepivacaine and etidocaine

D) Procaine and tetracaine

A

Answer: B) Prilocaine, benzocaine, and lidocaine

34
Q

What are potential causes of drug-induced liver injury from local anesthetics like bupivacaine and lidocaine?

A) Direct toxic injury, allergic reaction, or idiosyncratic metabolic abnormality from additives

B) Overdose due to excessive administration

C) Contamination of the drug with bacteria

D) Drug interactions with other medications

A

Answer: A) Direct toxic injury, allergic reaction, or idiosyncratic metabolic abnormality from additives

35
Q

What is a notable precaution when administering local anesthetics during pregnancy?

A) Decreased sensitivity of local anesthetics

B) Increased sensitivity to local anesthetics

C) No change in sensitivity to local anesthetics

D) Enhanced metabolism of local anesthetics

A

B) Increased sensitivity to local anesthetics

A Baseline Pharma (53 decks)

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