Therapeutics 1 - commonly prescribed analgesics Flashcards
what are the most commonly prescribed analgesics ?
- aspirin
- ibuprofen
- paracetamol
- diclofenac*
- naproxen*
- need prescription for these
how is arachidonic acid formed ?
- breakdown of phospholipid bilayer by phospholipid metabolism which releases phospholipids
- which convert into arachidonic acid
what does arachodinc acid metabolised into ?
- prostaglandins and thromboxane A2 thru cyclo- oxygenase COX pathway
or - leukotrienes thru lipoxygenase pathway
what do prostaglandins and thromboxane A2 cause?
pain
platelet aggregation
stomach mucus
increased PH
what do leukotrienes cause?
bronchoconstriction
what happens when tissue is damaged or there is an infection?
- influx of WBC - in order to mop up any damaged cells in order to mop up bacteria
- inflammation
- increased blood flow
- increased temp - eg. thrombxoanes and prostaglandins can act on your temp regulatory system in order to give you a fever
- all of these above can cause pain
give examples of anti inflammatory drugs ?
steroids such as prednisone
give eg of NSAIDs?
ibuprofen
aspirin
dicofenac
naproxen
how are NSAIDS involved in the cycloxygenase pathway ?
inhibit the enzyme and thus prevent the metabolism of arachidonic acid to produce prostaglandins and thromboxane A2
what are the different types of cyclo- oxygenase ?
cox1 = involved in gastric secretion.
*inhibiton increases risk of gastritis and ulceration
cox 2= inflammatory response, platelet function (interested in this one)
which COX will be inhibited by NSAIDS ?
both 1 and 2
what is a side effect of taking NSAIDS?
- they inhibit cox1 which causes gastritis, indigestion, gastric ulcers
- risk of bronchospasm
what are some effects of aspirin?
it has an irreversible effect on platelets so theres no point telling patients to stop taking aspirin before treatment
what happens when we inhibit cox pathway ?
- we don’t inhibit the lipoxygenase pathway which pushes arachidonic acid towards lipoxygenase pathway which produces more luekotrienes which causes bronchospasm
- need to know if pts have asthma and if they do have thye had unwanted bronchoconstriction when taking NSAIDs
list some cox2 inhibitors? and why are they not used anymore?
celecoxib, rofecoxib, etoricoxib
less gastritis but linked to cardiac effects
what is paracetamol ?
- NSAIDS
- works in a different way
- anti pyretic effect
what happens if you overdose on NSAIDs?
- metabolic effects
- hyperventilation
- hallucinations
- tinittus
- coma
what happens if you overdose on paracetamol ?
- can get poisoning
- normally metabolised by conjugation
- but one of the metabolites is toxic (NAPQI) and if accumulated in liver can cause death of liver cells and drug induced hepatitis
- tx= infusion of n- acetyl cysteine NAD) which metabolises NAPQI
who is aspirin prescribed for ?
at risk of CVD, cerebrovascular disease due to its anti platelet action
when do we not prescribe NSAIDS ?
when pts take anti coagulants
pregnant or breast feeding
