Mechanisms of Anaesthesia Flashcards
Which type of analgesia blocks nerve conduction?
Local anaesthetics
Where do delta receptors act as analgesics?
Spinal
Peripheral
Which type of opioid receptors are associated with sedation dysphoria and hallucinations?
Kappa
What are the respiratory effects of opioids?
Apnoea
What are the cardiovascular effects of opioids?
Orthostatic hypotension
How can morphine cause asthma attacks?
Causes mast cell degranulation which triggers bronchospasms
How do opioids cause nausea?
Act on CTZ outside the BBB
Decrease motility via enteric neurons via mu and delta receptors
What are the GI side effects of opioids?
Nausea
Vomiting
Constipation
Increased intrabilliary
What are the CNS effects of opioids?
Confusion, euphoria, dysphoria, hallucinations, dizziness, myoclonus
How is morphine metabolised?
Glucorinidation at 3 and 6 position to M3G and M6G
M6G excreted by the kidney
Which is the active metabolite of morphine?
M6G
Is oxycodone more/less potent than morphine?
3x more
What is diamorphine mostly used for?
Severe post op pain
Labour
Which is more lipophilic morphine or diamorphine?
Diamorphine
What is codeine metabolised to and how?
Via p450s in hepatic metabolism
To morphine
How is fentanyl given?
IV
Transdermal or buccal in chronic pain
How do opioids works as analgesics?
Act to open inhibit VGCCs and open K+ channels on projection neurons of nociceptors
Which receptor is responsible for most of the analgesic action of opioids?
Mu
Describe the onset of action of pethidine
Rapid (when given IV, IM, s/c)