Analgesics Flashcards
COX1 v 2
1 - antiplatelet, GI side effects
2 - antipyretic, analgesic, prothrombotic side effects
COX 2 selective inhibitor
celecoxib, meloxicam
Tolerance to opioids - not developed to
miosis, constopation, seizures
some tolerance to bradycardia
Withdrawal timeframe opioids
meperidine - <24h
morphine and fentanyl - onset 6-10h, peak 36-48h, lasts 5/7
Methadone - peak several days, 2w total
MOAI and opioids
Risk seratonin syndrome and hyperpyrexic coma
inc BP
Phenanthrenes
strong agonist - morphine and heroin
Mild-mid - codeine and oxycodone
mixed - buprenorphine (mu agonist, kappa antagonist)
Phenylheptylamines
strong - methadone
mild - propoxyphene (half the strength codeine)
Phenypiperidines
strong - meperidine and fentanyl
mild-mid agonists - diphenoxylate, loperamide
Fentanyl type drugs
sufentanyl -5x stronger
alfentanyl - less potent but faster T1/2 15m-30m
remi - shortest length 5m
Morphinans
strong agonist - levorphanol
mixed - butorphanol (kappa agonist)
Tramadol
blocks seratonin and NA uptake
Weak mu agonist
Tox - seizures, N&V
Has active metabolite
Opioid antagonists
naloxone lasts 1-2h
naltrexone - PO good absorb but high 1st pass T1/2 10h, lasts 48h
nalmefene - IV version naltrexone
Risk of seratonin syndrome with MAOIs and which opiods
tramadol, pethidine, dectromethorphan
Duration analgeisa opiates
codeine - 3-4h
morphine - 4-5h
methadone - 4-6h
Buprenorphine - 4-8h (can reduce etoh cravings)
Opioids without active metabolites
methadone and fentanyl
piroxicam half life
57 hours
Opioid with cardiotoxicity
Dextroprpoxyphene
NSAID with GI SEs
Indomethacin (cox1>2)
Methadone bioavailability
75%
Colchicine mechanism
Binds tubulin so cant polymerise into microtubules
Inhibits leukocyte migration
Inhibits leukotriene B4
Does not affect urates
Colchicine pk
Rapid absorption peak plasma 2h
Deacytelation liver
Excreted 90% in stool
SE colchicine
GI bleed
Aplastic anaemia
Hair loss
Throat pain
Bloody diarrhoea
Allopurinol SEs
Rash
Fever
Lfts
Sjs
Peripheral neuropathy
Aplastic anaemia and vasculitis
Inc warfarin and thiazides
Can be dialysed (not pb)
Interaction NSAIDs and ACIis
Decreased hypotensive effect of aceis
Unionised aspirin
More in acidic environment
Aspirin effect on probenecid
Inhibits uricosuric effect
Aspirin and uric acid
At low doses increases blood urate
