Local anaesthetic agents Flashcards

1
Q

What is lidocaine?

A

an amide

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2
Q

What is the role of lidocaine?

A

local

antiarrhythmic

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3
Q

which channels does lidocaine affect?

A

sodium channels in the axon

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4
Q

how is it metabolised?

A

hepatic

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5
Q

how is it excreted?

A

renal

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6
Q

how doe s lidocaine toxicity occur?

A

due to IV or excess administration. Increased risk if liver dysfunction or low protein states

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7
Q

what does lidocaine toxicity do to pH?

A

acidosis

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8
Q

how do you treat lidocaine toxicity?

A

IV 20% lipid emulsion

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9
Q

what drugs does lidocaine react with?

A

Beta blockers, ciprofloxacin, phenytoin

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10
Q

why does lidocaine toxicity occur?

A

Initial CNS over activity then depression as lidocaine initially blocks inhibitory pathways then blocks both inhibitory and activating pathways.

Cardiac arrhythmias.

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11
Q

When do you combine lidocaine with adrenaline?

A

to limit systemic absorption.

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12
Q

what is cocaine and how is it used as a local anaesthetic ?

A

Pure cocaine is a salt, usually cocaine hydrochloride.

It is supplied for local anaesthetic purposes as a paste.

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12
Q

what is cocaine and how is it used as a local anaesthetic ?

A

Pure cocaine is a salt, usually cocaine hydrochloride.

It is supplied for local anaesthetic purposes as a paste.

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13
Q

how is cocaine given?

A

topically to the nasal mucosa

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14
Q

what is the onset of cocaine?

A

rapid

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15
Q

systemic effects of cocaine

A

cardiac arrhythmias and tachycardia.

16
Q

use of cocaine

A

ent

rare

17
Q

how does bupivacaine work?

A

binds to the intracellular portion of sodium channels and blocks sodium influx into nerve cells, which prevents depolarization.

18
Q

why is it sometimes used instead of lignocaine?

A

longer duration

good for long surgeries

19
Q

when is bupivicaine contra-indicated?

A

cardiotoxic

regional blocks - in case tourniquet fails

20
Q

which is less cardiotoxic levobupivicaine or bupivicaine?

A

levobupvicaine - and causes les vasodilation

21
Q

what is a good choice local anaesthetic for regional anaesthesia?

A

it is far less cardiotoxic and is therefore the agent of choice for intravenous regional anaesthesia e.g. Biers Block.

22
Q

why is adrenaline added?

A

It prolongs the duration of action at the site of injection and permits usage of higher doses

23
Q

when is adrenaline contraindicated?

A

MaOIs

tricyclic antidepressants

24
Q

plain dose of lignocaine

A

3mg/Kg