NSAIDs Flashcards
what are the 3 therapeutic effects of NSAIDs
analgesia
anti-inflammatory
anti-pyretic
how do NSAIDs work
they competitively inhibit the active site for arachnionic acid on the COX 2 enzymes
how are prostaglandins synthesised
arachidonic acid is cleaved from cell membrane phospholipids. this is then converted into prostaglandins by cycle-oxygenase enzymes
which cox enzyme causes ADRs when blocked
cox 1
which cox enzymes slows for therapeutic effects when blocked
cox 2
describe the pain pathway
nociceptors detect pain and send signals through afferent C fibres
this travels in the spinothalamic tract to the somatosensory Cortex
how do prostaglandins produce pain
PGE2 binds to EP1 receptors on C fibres
this increases the activity of the fibre to cause pain
what happens to prolonged pain
- there becomes an increase in cox 2 and PGE2 synthesis to increase sensitivity to pain
- lack of production of glycine mean pain c fibres cant be inhibited
how do prostaglandins contribute to pyrexia
PGE2 binds to EP3 receptors to cause an increase in heat production and decreased heat loss
what stimulates PGE2 synthesis to cause pyrexia
the release of interleukin 1 from macrophages
what happens when sulphonylurea is given with NSAIDs
hypoglycaemia
what happens when warfarin is given with NSAIDs
increased bleeding
how do aspirin work differently to other NSAIDs
binds irreversibly to inhibit cox enzymes
how does aspirin affect the CVS system
inhibits platelet cox enzymes, preventing platelet aggregation - meaning its cardio protective
what are the 3 types of endogenous opioids
beta-endorphin
met-enkephalin
leu-enkephalin
what are the 3 types of opioid receptors
mu, delta and kappa
what is the mechanism of action of opioids
they are agonists of the Gi opioid receptors
this inhibits GABAergic neurones meaning they don’t inhibit the interneurones - so these are excited
they are inhibitory enkephalic interneurones so these therefore inhibit pain
what are opioids used for
acute pain, cancer pain, RA, diarrhoea, constipation, IBS, cough
what drug is used in opioid overdoses
naloxone
what are the side effects of opioids
respiratory distress, nausea, vomiting, constipation
what are the adverse drug reactions of NSAIDs
GI affects - gastric bleeding and ulcers
reduce GFR
skin rashes
increased bleeding time
what can be given to offset the GI side effects given from NSAIDs
PPI
why aren’t selective cox 2 inhibitors used
adverse effects on the CVS
why are gastric side effects common for NSAID use
prostaglandins normally allow for good mucosa blood flow, mucus secretion and a reduction in acid production
what drug is given in paracetamol overdose
n-acetylcystine
what causes toxicity to cells in a paracetamol overdose
NAPQI build up
