pharma Flashcards
what is the analgesic ladder
- paracetamol +/- NSAIDS // 2. weak opioids eg codeine, tramadol // 3. strong opioids eg morphine, oxy
where is pain processed in the brain
cortex, amyglada, thalamus
which brainstem nuclei are excited in descending pain pathway (3)
PAG, locus coeruleus, nucleus raphe magnus
which pathways are activated in descending nociceptive pathway
serotonergic and enkephalinergic
how does lidocaine or nerve blockers work
inactivate sodium channels for ascending nociceptive pathway
how do opioids prevent pain
inhibit Ca channels (stop depolarisation) // open K channels to suppress excitation of projection neurones // act in both ascending and descending pathway
what are the 3 opioid receptors and where are they usually found
mu (y), delta, kappa // cortex, limbic system + brainstem
SE opioids
resp apnoea // orhtostatic hypotension // braducardia // N+V // constipation // euphoria, hallucinations
what are strong opioids
morphine, diamorph (heroine), fentanyl (anaesthetics)
what are weaker opioids
coedine, buprenorphine, tramadol
what opioid is given in child birth
pethidine
what opioid is slow acting and used in chronic pain
Buprenorphine
what drug reverses opioid toxicity
naloxone (antagonist of mu receptor) // naltrexone or alvimopan
what is the function of COX
synthesises phospholipids –> PGE
what is the role of prostaglandin in pain regulation
lower nociceptive activation threshold, recruit inflamm mediators
difference between COX 1 and 2
COX 1 is systemic but COX2 only at side of injury
mechanism NSAIDs
inhibit COX
SE NSAIDs
ulcers, COX2 prothrombotic
mechanism gabapentin and pregabalin
reduce Ca channels upregulated in damaged sensory nerves // decrease NT eg glutamate
mechanism TCA
recrease reuptake of NA and 5HT which both enhance descending pathway
where do 5HT3 antagonists mainly work
medulla oblongata
examples 5HT3 antagonists
ondasetron
indication 5HT3
chemo nausea
SE 5HT3
prolonged QT and constipation
