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Block 7 Week 2 > Duan: Local anesthetics > Flashcards

Duan: Local anesthetics Flashcards

1
Q

Do local anesthetics cause a loss of consciousness?

A

no

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2
Q

What do local anesthetics do?

A

block axonal conduction in nerves when applied in appropriate concentrations

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3
Q

Local anesthetics have a completely (blank) reaction

A

reversible

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4
Q

What drug was discovered in 1860 by German chemist Albert Niemann?

A

cocaine

**made his tongue feel numb

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5
Q

What did Sigmund Freud do with cocaine?

A

used it to treat morphine addiction

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6
Q

What did Carl Koller (ophthalmologist) do with cocaine?

A

used it as the first local anesthetic on glaucoma patients

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7
Q

What happened to Von Anrep, Freud, and Koller as a result of self-experimentation w cocaine?

A

they became addicted

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8
Q

Cocaine is an (blank) that is a potent (blank) stimulant

A

ester; CNS

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9
Q

Cocaine is a potent sympathomimetic and (blank)

A

vasoconstrictor

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10
Q

What unfortunate events can cocaine cause?

A

fatalities from arrhythmias (v fib), MI, or seizures

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11
Q

the first synthetic local anesthetic drug (1898), derivative of cocaine, slow onset , short duration, less potent, higher potential to cause allergic reactions, sympathomimetic (release adrenaline) increase heart rate, feel nervous

A

Procaine (Novocaine)

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12
Q

slightly more potent with shorter duration of action than procaine

A

Chloroprocaine (Nesacaine)

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13
Q

10 times more potent with slower onset and longer duration of action than procaine

A

Tetracaine (Pontocaine)

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14
Q

does not contain the terminal hydrophilic amine group, only slightly soluble in water, slowly absorbed with prolonged duration

A

Benzocaine

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15
Q

What is unique about Benzocaine?

A

it is only useful as a topical anesthetic

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16
Q

List 4 ester local anesthetics and the duration of action/potency

A

cocaine - medium duration, potency =2
procaine - short duration, potency =1
tetracaine - long duration, potency =16
benzocaine **surface use only

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17
Q

Lidocaine is an (blank) with execellent potency (2-3x more potent that procaine)

A

amide

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18
Q

What should lidocaine be combined with to increase its duration of action?

A

epinephrine

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19
Q

What is lidocaine used for?

A 
surface anesthesia
peripheral nerve block
infiltration anesthesia
spinal anesthesia
epidural anesthesia 
antiarrhythmia
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20
Q

This is an amide that is pharmacologically similar to lidocaine; it is coadministered w epi to prolong duration of action

A

Mepivacaine

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21
Q

What is mepivacaine used for?

A

cardiovascular disease in elderly patients

22
Q

What is unique about mepivacaine?

A

not useful in obstetrics bc of prolonged metabolism in fetus and neonate, which increases toxicity risk

23
Q

This is an amide that is 10x more potent than procaine and has a particularly LONG duration of action (24hrs)

A

Bupivacaine

24
Q

This is an amide with duration of action similar to bupivacaine, but slightly less potent

A

Ropivacaine

25
Q

What is the mechanism of action of local anesthetics?

A

block voltage-gated Na+ channels in neuronal membranes that are responsible for signal propagation - the postsynaptic membrane will not depolarize and will thus fail to transmit an AP

26
Q

How is specificity of anesthetics obtained?

A

by route of administration

**highly effective analgesia (loss of pain sensation) in well-defined regions

27
Q

Which nerves should be blocked first?

A

small-diameter, unmyelinated nerve fibers

large-diameter, myelinated fibers less susceptible and require greater doses to achieve neural blockade

28
Q

What is more important to consider with nerves, size factor or myelination?

A

size factor

29
Q

Rank the following in terms of predominant nerve blockage:

small myelinated fibers
small unmyelinated fibers
large myelinated fibers

A

small unmyelinated > small myelinated > large myelinated

30
Q

What is the order of sensory loss of the following?

touch
pressure
pain
temp

A

pain (lost first) > temp > touch > pressure (lost last)

31
Q

What are 3 routes of administration for anesthetics?

A

regional: injected into area of nerve fibers to be blocked
topical: surface use; esp on mucous membranes
infiltration: inject under skin (often used with epinephrine to cause vasoconstriction)

32
Q

When you get give anesthesia via an infiltration method (injected under skin), what should it be given with?

A

epinephrine

**causes vascular constriction

33
Q

Where is spinal vs epidural vs caudal anesthesia injected?

A

spinal: subarachnoid space
epidural: outside of subarachnoid space, diffuses into subarachnoid space
caudal: epidural space of the sacral canal

34
Q

What procedures usually require a spinal anesthetic? Where is it injected?

A

upper-abdominal surgery; injected into subarachnoid space

35
Q

What procedures usually require a caudal anesthetic? Where is it injected?

A

perinea and rectal procedures; injected into epidural space of sacral canal

36
Q

What are epidurals usually used for? Where is it injected?

A

ob: labor and delivery, C-section; administered outside, but diffuses into subarachnoid space

37
Q

What are three factors that affect the reaction of local anesthetics?

A

lipid solubility: the higher the lipid solubility, the faster nerve penetration, and onset of action

pH influence: all local anesthetics are weak bases - decreased pH shifts equilibrium toward ionized form, which delays the penetration of the drug

blood flow: vasoconstrictors (epi) are used to limit the vasodilation activity of local anesthetics

38
Q

What is the pH equation we should be aware of?

A

log(ionized/uncharged form) = pKa - pH

39
Q

What is the pH of all local anesthetics?

A

weak bases (pH 8-9)

40
Q

What does a decrease in pH do to onset of action of local anesthetics?

A

shifts the equilibrium to ionized form, delaying penetration of the drug and onset of action

41
Q

Why would you want to vasoconstrict when giving local anesthetics?

A

to keep the drug around longer and delay the systemic absorption of the drug into the bloodstream

42
Q

Which anesthetics, esters or amides, are very rapidly hydrolyzed in blood

A

esters

43
Q

Hydrolysis of esters yields (blank)

A

paraaminobenzoic acid (PABA)

44
Q

almost completely biotransformed in liver by amidases and undergo N-dealkylation followed by hydrolysis by liver microsomal cytochrome P450

A

amides

**pts with liver disease or taking other drugs affecting cyto P450 will reduce the biotransformation of amides

45
Q

What do moderate doses of anesthesia do to the CNS? What do very high doses do to the CNS?

A

stimulate CNS; depress CNS

46
Q

What affects do anesthetics have on the cardiovascular system?

A

depress myocardium
reduce excitability
lower contractility
slow conduction

47
Q

Which anesthetic causes vasoconstriction?

A

cocaine

48
Q

Which anesthetics have the highest rate of hypersensitivity reactions?

A

esters, bc they form PABA which is known to be allergenic

49
Q

What is the most common cause of toxicity w anesthetics?

A

high dose and systemic concentration due to unintentional intravenous injection

50
Q

What are three toxic affects we should be aware of when administering anesthesia?

A

cardio toxicity
allergic reaction
neurotoxicity

Block 7 Week 2 (9 decks)

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