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Pharmacology > Exam 11: Local Anesthetics > Flashcards

Exam 11: Local Anesthetics Flashcards

1
Q

Which part of local anesthetics’ structure is important for their entry into the axon?

A

Lipophilic domain

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2
Q

Which part of local anesthetics’ structure is important for their action at Na+ channels?

A

Hydrophilic domain

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3
Q

What are the two types of local anesthetics?

A

Amides (lidocaine)

Esters (procaine)

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4
Q

How are Amide local anesthetics metabolized?

A

Liver (microsomal enzymes)

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5
Q

How are Ester local anesthetics metabolized?

A

Plasma cholinesterase

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6
Q

How do the half-lives of Amides compare to Esters?

A

Amides have longer half-lives because they’re metabolized by liver enzymes as opposed to Esters, which are metabolize by cholinesterase in the plasma

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7
Q

Which chemical form of local anesthetics enters the cell?

A

Unprotonated (LA)

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8
Q

Which chemical form of local anesthetics is “active” in inhibiting the Na_ channels?

A

Protonated (LAH+)

Intracellular pH is lower than extracellular

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9
Q

What is the order of neuron sensitivity to nerve block?

A 
Most to least sensitive:
C (pain)
B (autonomics)
A' (pain/temp)
A (motor)
A+ (motor)
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10
Q

How can you numb an entire limb?

A

Intravenous regional anesthesia
Put a tourniquet on and inject LA IV
Only useful up to 2 hours

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11
Q

Spinal vs Epidural: Which needs more LA

A

Epidural

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12
Q

Spinal vs Epidural: Which is more intense of a block?

A

Spinal

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13
Q

3 Advantages of Epidural over spinal anesthesia

A
  1. Not limited to below L2
  2. No dural puncture = no post-dural puncture headache
  3. You can leave a catheter in for long-term pain reduction and fine tune the dosage from there
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14
Q

Purpose of giving Epinephrine injection with local anesthetics

A

Causes vasoconstriction and decreasing absorption

Prolongs duration of effect and reduces the amount of LA needed

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15
Q

2 cautions with epinephrine injection

A
  1. Can cause vasodilation at skeletal muscle beds, increasing toxicity
  2. Dont use it at peripheral sites (nose, fingers, scrotum, ears)
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16
Q

Where can local anesthetics distribute?

A

Everywhere (cross BBB)
Amides are taken up in fat, brain, kidney, liver, muscle, gut.
Esters are metabolized too fast to be redistributed

17
Q

What does CSF lack?

A

Cholinesterase

18
Q

Local anesthetic side effects at low doses

A

Sleepiness, dizziness, restlessness

Lidocaine can cause euphoria

19
Q

Local anesthetic side effects at high doses

A

Nystagmus, shivering, CNS depression, respiratory failure, convulsions

20
Q

Treatment for local anesthetic toxicity

A

Benzos and barbiturates

21
Q

Only local anesthetic with intrinsic vasoconstrictive properties

A

Cocaine

the rest are vasodilators

22
Q

Which local anesthetic is the most cardiotoxic?

A

Bupivacaine

23
Q

Which 2 local anesthetics can cause methemoglobinemia?

A

Prilocaine

Benzocaine

24
Q

2 Amide Local Anesthetics

A

Lidocaine
Bupivacaine
Ropivacaine
Articaine

25
Q

2 Ester Local anesthetics

A

Benzocaine

Cocaine

26
Q

What is the most widely used Local Anesthetic today?

A

Lidocaine

27
Q

Lidocaine

A

Amide Local anesthetic
Widely used (including spinals, epidurals, IV)
Excellent diffusions and penetration

28
Q

Bupivacaine

A

Amide Local Anesthetic
Long Duration of Action!!!
Not recommended for IV injection due to cardiotoxicity

29
Q

Caution with Bupivicaine

A

Dont inject IV

Cardiotoxic

30
Q

Ropivacaine

A

New Amide local anesthetic
Useful for procedures where you don’t want motor block (labor anesthesia) because it’s less lipophilic than bupivacaine
Reduced CNS/Cardio toxicity
Pure enantiomer

31
Q

Articaine

A

Amide Local Anesthetic

Safer than prilocaine because it metabolized by plasma carboxyesterase (less metabolized in liver)

32
Q

Benzocaine

A

Ester local anesthetic
Used topically (skin/mucus membranes)
FDA warning for use in children due to methemoglobinemia

33
Q

Cocaine!!!

A

Topical use only
Only Local anesthetic with inherent vasoconstrictive action
No need to co-administer with epi, this could increase toxicity

Pharmacology (34 decks)

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