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Pharmacology Pt. 2 > Local anesthetics > Flashcards

Local anesthetics Flashcards

1
Q

What is the definition of a local anesthetic?

A

Any substance that produces a reversible nerve blockade.

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2
Q

What are the two major types of local anesthetics?

A

Amides and esters

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3
Q

Drugs with two i’s in the name are _____. Drugs with one i are _____.

A

amides - two i’s

esters - one i

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4
Q

Where in the body are esters metabolized? By what enzymes?

A

In the blood by plasma or pseudocholinesterase

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5
Q

What is the half life of an ester LA?

A

minutes

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6
Q

Degradation of ester LA’s forms _____. Is the metabolite toxic? Can people be allergic to this?

A

PABA is toxic and a possible allergen.

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7
Q

Where are amide LAs metabolized? By what enzymes?

A

In liver by CYP450

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8
Q

What is the half life of an amide LA?

A

Hours

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9
Q

Does renal disease affect LA dosing?

A

Nope

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10
Q

Does pregnancy affect LA metabolism?

A

Yes, metabolism is slowed (half life increases)

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11
Q

Are sepsis, malignany, and cardiac ischemia significant clinically in dosing LAs?

A

Nope

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12
Q

What is the mechanism of action of local anethetics?

A

They bind to receptors inside Na+ channels and decrease the rate of rise of the action potential so the depolarization threshold is not reached.

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13
Q

What is the most important factor in onset of action of a LA? Explain.

A

pKa must be close to physiological pH so that the drug can dissociate from the protonated form to cross the cell membrane, then reassociate with a proton inside the cell to enter the sodium channel and bind the receptor.

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14
Q

Are LAs weak acids or weak bases?

A

weak bases

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15
Q

What is the most important factor in the potency of a LA?

A

Lipid solubility. More lipid solubility = greater potency.

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16
Q

What is the most important factor in the duration of action of a LA?

A

Protein binding. More protein binding = longer duration

17
Q

Name the three major clinical effects of LAs in their correct order.

A
  1. Sympathetic block (vasodilation/skin temp)
  2. Sensory block
  3. Motor block
18
Q

Which is more easily blocked: myelinated or non-myelinated nerves?

A

Myelinated

19
Q

What are the signs of systemic LA toxicity in the correct order?

A

1st - light-headedness and numb tongue and lips
2nd - respiratory arrest
Last - cardiovascular depression

20
Q

How is systemic LA toxicity treated?

A

Lipid infusion to pull lipid soluble drug out of cells and into the “lipid sink” in the blood.

21
Q

Are pregnant women more susceptible to systemic toxic effects of LAs?

A

Yeah

22
Q

What is a major side effect of benzocaine and prilocaine (local anesthetics)?

A

They can oxidize Hb –> metHb

23
Q

True or false: Local anesthetics cause the reversible interruption of afferent and efferent neural conduction.

A

True

24
Q

popular local anesthetics

A

lidocaine

25
Q

local anesthetics are _____ bases

A

weak bases; accept hydrogen ions

26
Q

benzene ring

A

lipophilic group

27
Q

tertiary amine

A

hydrophilic group

28
Q

severe liver dx with local anesthetics can occur if someone has

A

decreased cholinesterase activity

29
Q

onset of action

A

pKa

30
Q

lipid solubility has the ability to

A

cross nerve membranes easily

31
Q

Duration: Lidocaine is a

A

shorter acting

32
Q

Duration: Bupivivan is a

A

longer acting

33
Q

large abcesses causes a low pH environment leading to

A

local anesthetics not being able to cross over

34
Q

high levels of local anesthetics can be

A

neurotoxic

35
Q

most toxic absorption is

A

intravenous

36
Q

which drug has a narrow therapeutic margin?

A

Bupivacaine

37
Q

which drug is preferentially not used in pregnancy?

A

Bupivacaine–> causes maternal cardiac arrest

38
Q

cocaine is what type of local anesthetics?

A

Ester LA

Pharmacology Pt. 2 (7 decks)

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