Pharmacology - Test 2 - Local Anesthetics Flashcards

1
Q

Goals for LA use

A

minimize local irritation.
minimize systemic toxicity.
rapid onset: high % needed
sufficient duration

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2
Q

amide metabolism

A

in the liver. protein binding

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3
Q

ester metabolism

A

plasma pseudocholinesterase

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4
Q

Mechanism of action for LA

A

Identical to one of the Anti convuls/epilep drug mechanisms. Block Na channels from the inside of channel. Stabilize inactived state.

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5
Q

Quartenary lidocane and nerve effects

A

ineffective from outside. must be injected directly into nerve.

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6
Q

Effect of block on nerve myelination and diameter.

A

Small and unmyelinated are most sensitive to effect.

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7
Q

Order of sensory/motor nerve block sequence

A

pain > cold > touch > deep pressure > motor function

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8
Q

7 factors influencing effectiveness of LA

A

Fiber diameter, firing rate (action potential duration - use dependent block), position of fiber in nerve bundle, local blood flow, drug size and hydrophobicity, liver function (amines). Tissue pH - consequence of inflammation

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9
Q

2 Considerations when using epinepherine in local.

A

Location of block (distal portion also being blocked). Slows local blood flow.

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10
Q

PkA of lidocaine

A

7.9

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11
Q

At more acidic pH (lidocaine)

A

less drug is uncharged and less drug crosses nerve membranes, and therefore less nerve block.

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12
Q

Toxicity of LA on CNS

A

Drowsiness, seizures (excitation), followed by general depression, coma

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13
Q

Toxicity of LA on Cardiac

A

Depressed pacemaker activity, decreased conduction, arrhythmias, potentiated by hperkalemia, amides synergize with anti-arrhythmic drugs to induce arrythmias

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14
Q

Toxicity of LA on vessels

A

vasodilation leading to hypotension (except cocaine - HTN caused by block of NE reuptake)

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15
Q

LA common allergies

A

esters: PABA derivatives. Amides: Preservatives

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16
Q

Most broadly used local anesthetic

A

lidocaine

17
Q

Lidocaine, Amide or ester?

A

amide

18
Q

Duration of lidocaine

A

30-60 minute, 2hr spinal

19
Q

Toxicity of lidocaine

A

higher systemic toxicity than ester-linked drugs

20
Q

Metabolism of lidocaine

A

metabolized by liver

21
Q

Uses of lidocaine

A

spinal, epidural, local, topical anesthesia

22
Q

Drug to be cautious of with Lidocaine

A

amiodarone (muscarinic antagonist)

23
Q

Procaine, ester or amide?

A

esters: PABA derivatives. Amides: Preservatives

24
Q

Toxicity of procaine

A

low

25
Q

Main use of Procaine

A

infiltration and regional anesthesia

26
Q

Procaine interaction

A

PABA blocks sulfonamide.