CPTP 4.21-23 Flashcards
e.g. of step 2 WHO analgesic ladder drugs
codeine, tramadol
new adaptation of analgesic ladder
encourages bidirectional application, can start at top in some cases. adds a 4th step - nerve blocks, epidurals,
COX 1 function
gastroprotection, dilates afferent renal arterioles, makes thromboxane - platelet aggregation
COX 2 function
induced by pain and inflammation
What kind of asthmatic are NSAIDs contraindicated in
aspirin sensitive (can make them wheezy)
pharmodynamics of codeine
converted to morphine in liver and acts on mew receptors
why is codeine ineffective in some and toxic in others?
variable expression of enzymes in population, poor metabolisers (ineffective) and excess metabolisers (toxic). as metabolite = morphine?
what should you co-prescribe with codeine
laxatives
are tramadol’s effects reversed by naloxone
not totally
good opioid after bowel surgery
tramadol - not as constipating
tramadol mechanism of action
prevent serotonin and NE reuptake, NMDA antagonist,, ACh (nicotinic) antagonist.
opioid receptor - signal transduction?
g protein coupled
side effects of tramadol
serotonin syndrome, anticholinergic SEs, opiate side effects
types of morphine
MST - morphine sulphate tablets, zomorph (modified release), oramorph (liquid), sevredol (tablet form of immediate acting), diamorphine (IV), oxycodone, fentanyl
morphine mechanism of action
acts on µ-opioid receptors
analgesic ass with pruritus side effect
opiates
what do you prescribe for breakthrough pain when on morphine
PRN morphine - 1/6-1/10 total regular dose in 24h
timing of morphine doses?
either immediate release 4hrly or modified release 12 hrly
e.g. of immediate release morphine
oramoph, sevredol tablets
MR morphine?
zomorph
opioid by patch?
fentanyl, buprenorphine
early sign of opiate toxicity
myoclonic jerks
other signs of opiate toxicity
pin point pupils, hallucinations, confusion, reduced RR
reason for opiate toxicity in 90% cases?
AKI
adjuvant in muscle spasm/cramp
baclofen
adjuvant in bone pain (bone mets, breast cancer, myeloma)
bisphosphonates (pamidronate in myeloma)
adjuvant in abdomen spasms
hyoscine butyl bromide
administration route at the end of life
SC (injections and infusions)
prescribing for pain at EOL if eGFR > 30
morphine
prescribing for pain at EOL if eGFR <30
alfentanil (less renally excreted)
prescribing for N&V at EOL if eGFR >30
cyclizine
prescribing for N&V at EOL if eGFR<30
haloperidol
agitation at end of life (prescription)
midazolam
tx of secretions at EOL if GFR >30
hyoscine hydrobromide
tx of secretions at EOL if GFR <30
hyoscine butylbromide (buscopan)
neuropathic pain mx options
TCAs (amitriptyline), SSRIs, Gabapentin (FIRST LINE), Pregabalin, ketamine (if all else fails), lidocaine
rule on increasing morphine dose in 24h
shouldn’t increase by > 50%
mx of opioid side effects
opioid rotation (tramadol, fentanyl patches), reduce dose and add adjuvant
conversion of morphine oral to SC
/2
breakthrough pain at the end of life
prescribe 1/6 of syringe driver dose SC
What is the most appropriate opiate to use in renal failure via a syringe driver
Alfentanil (30 times more potent than oral morphine however)
