Anaesthetic drugs Flashcards
Common IV induction agents
- Propofol
- Sodium thiopentone
- Ketamine
- Etomidate
PESK = induction agents
Propofol - how does it work, what should you know about it
- GABA agonist
- Rapid onset
- Pain on IV injection
- Antiemetic properties
- Rapid metabolism, little accumulated metabolites
- Moderate myocardial depression
- Very common for maintaing sedation on ITU, total IV anaesthesia and daycase
Sodium thiopentone - what to know about it
- Extremely rapid onset - choice for rapid sequence induction
- Marked myocardial depression
- Metabolites build up
- Unsuitable for maintenance infusion
- Little analgesic effects
thiopentONE - fastest ONE
Ketamine - how does it work, what should you know about it
- NMDA receptor antagonist
- Induction
- Moderate to strong analgesia
- Little myocardial depression - good for haemodynamically unstable patients
- Dissassociative anaesthesia can occur - nightmares
Ketamine makes me dream
Etomidate - what to know about it
- Good cardiac safety progile
- No analgesia
- Unsuitable for maintainance - prolonged use can cause adrenal supression
- Post op vomitting = common
TOM made me vomit on the DATE
Inhaled general anaesthetics
- Volatile liquids eg isoflurane, desflurane, sevoflurane
- Nitrous oxide
MOA of volatile liquids
- Unknown really
- May act in combo of GABA A, glycine and NMDA receptors
Adverse effects of volatile liquids
- Myocardial depression
- Malignant hyperthermia
- Halothane - not really used now is hepatotoxic
What are volatile liquids used for?
Induction and maintenance
Nitrous oxide MOA
- Unknown
- May be combination of NMDA, nACh, 5-HT3, GABAa and glycine
Adverse effects nitrous oxide
- May diffuse into gas filled body compartments
- = increase in pressure
- So avoid in certain conditons eg pneumothorax
Use of nitrous oxide
Maintenance and analgesia (eg during labout)
IV general anaesthetics
- Propofol
- Sodium thiopentone
- Etomidate
- Ketamine
MOA of thiopental
- Barbiturate - potentiates GABAa
Adverse effects thiopental
- Laryngospasm
What is important to remember about thiopental?
- Lipid soluble
- Quickly affects brain
Adverse effects of propfol
- Pain on injection - activates pain receptor TRPA1
- Hypotension
Adverse effects Etomidate
- Primary adrenal supression - reversible inhibition of 11b-hydroxylase
Adverse effects of ketamine
- Disorientation
- Hallucinations
Local anaesthetic agents examples
- Lidocaine
- Cocaine
- Bupivacaine
- Prilocaine
How to treat local anaesthetic toxicity?
- IV 20% lipid emulsion
Drug interactions with lidocaine
- Beta blockers
- Ciprofloxacin
- Phenytoin
Features of lidocaine toxicity
- Intial CNS overactivity (blocks inhibitory pathways first)
- Then depression (blocks both)
- Cardiac arrhythmia
When is cocaine used?
- Salt, local anaesthetic is paste form
- Topically on nasal mucosa - vasoconstriction
- Used in ENT surgery
Bupivacaine vs lidocaine
- Bupivacaine = longer duration of action
- Used for topical wound infiltration and at the end of surgery for long analgesic effect
- BUT is cardiotoxic so cannot be used for Biers block - if tourniquet fails
Prilocaine use
- Far less cardiotoxic
- Used for Biers block
Two types of drugs which can be used for paralysis in anaesthetics
- Non polarising neuromuscular blockers
- Depolarising neuromuscular blockers
MOA of depolarising drugs
- Binds to nictotinic acetylcholine receptors
- = Persistent depolarisation of motor end plate
MOA of non-depolarising drugs
Competitive antagonist of nicotinic acetylcholine receptors
Examples of depolarising drugs
- Succinylcholine (AKA suxamethonium)
Examples of non-depoalrising drugs
- Tubcurarine
- Atracurium
- Vecuronium
- Pancuronium
Adverse effects of depolarising agents
Malignant hyperthermia
Adverse effects of non-depolarising agents
Hypotension
Reversal of non-depolarising agents
Acetylcholinesterase inhibitors eg Neostigmine
As more Ach accumulates, it out competes the drug
Things to know about depolarising drugs
- Muscle relaxant of choice
for rapid sequence induction for intubation - May cause fasiculations
What are the contraindications of Suxamethonium?
- Penetrating eye injuries
- Acute narrow angle glaucoma
- It increases intra-ocular pressure
