Local anaesthetic agents Flashcards
What is lidocaine?
an amide
What is the role of lidocaine?
local
antiarrhythmic
which channels does lidocaine affect?
sodium channels in the axon
how is it metabolised?
hepatic
how is it excreted?
renal
how doe s lidocaine toxicity occur?
due to IV or excess administration. Increased risk if liver dysfunction or low protein states
what does lidocaine toxicity do to pH?
acidosis
how do you treat lidocaine toxicity?
IV 20% lipid emulsion
what drugs does lidocaine react with?
Beta blockers, ciprofloxacin, phenytoin
why does lidocaine toxicity occur?
Initial CNS over activity then depression as lidocaine initially blocks inhibitory pathways then blocks both inhibitory and activating pathways.
Cardiac arrhythmias.
When do you combine lidocaine with adrenaline?
to limit systemic absorption.
what is cocaine and how is it used as a local anaesthetic ?
Pure cocaine is a salt, usually cocaine hydrochloride.
It is supplied for local anaesthetic purposes as a paste.
what is cocaine and how is it used as a local anaesthetic ?
Pure cocaine is a salt, usually cocaine hydrochloride.
It is supplied for local anaesthetic purposes as a paste.
how is cocaine given?
topically to the nasal mucosa
what is the onset of cocaine?
rapid
systemic effects of cocaine
cardiac arrhythmias and tachycardia.
use of cocaine
ent
rare
how does bupivacaine work?
binds to the intracellular portion of sodium channels and blocks sodium influx into nerve cells, which prevents depolarization.
why is it sometimes used instead of lignocaine?
longer duration
good for long surgeries
when is bupivicaine contra-indicated?
cardiotoxic
regional blocks - in case tourniquet fails
which is less cardiotoxic levobupivicaine or bupivicaine?
levobupvicaine - and causes les vasodilation
what is a good choice local anaesthetic for regional anaesthesia?
it is far less cardiotoxic and is therefore the agent of choice for intravenous regional anaesthesia e.g. Biers Block.
why is adrenaline added?
It prolongs the duration of action at the site of injection and permits usage of higher doses
when is adrenaline contraindicated?
MaOIs
tricyclic antidepressants
