NSAIDs Flashcards
what are the three most important properties of NSAIDS?
- anti-inflammatory
- analgesic
- antipyretic
what enzyme do NSAIDS inhibit the action of?
cycle oxegenase (produces prostaglandins, thromboxjnes and prostacyclins from arachidonic acid)
which NSAID IRREVERSIBLY inhibits the action of cyclooxegenase?
ASPIRIN
how does aspirin irreversibly inhibit the action of COX?
by acetylating the serine amino group of COX (forms a covalent bond)
which drug binds irreversibly to COX and competes with the natural substrate?
ibuprofen
what are three chemicals produced by the action of COX?
prostaglandins and thromboxanes and prostacyclins
what is the effect of prostaglandins on the vasculature?
vasodilation
what is the effect of thromboxanes on the vasculature?
vasoconstriction (they are also thrombotic)
which enzyme liberates arachidonic acid from phospholipids?
phospholipase A2 (PLA2)
what substance is produced as a by-product of arachidonic acid?
platelet activating factor (PAF)
what are the two main types of COX enzymes?
COX-1 and COX-2
which COX enzyme is constitutive ad is important in maintaining the GI tract integrity?
COX-1
which COX enzyme is inducible and involved in inflammatory responses?
COX-2
how do prostaglandins act on pain sensory nerves?
increase the sensitisation of nociceptive nerves to histamine and bradykinin
how do prostaglandins promote the formation of oedema?
increase sensitivity of post capillary venues to histamine and bradykinin which increases venue permeability
what is the effect of prostaglandins on temperature and why is this?
prostaglandins increase the thermostat ‘set point’ in the hypothalamus
what causes the formation of prostaglandins in the brain?
release of interleukins from macrophages
which class of drugs give a number of unwanted side effects including stomach ulcers, tinnitus, dizziness, nausea, vomiting, acid/base imbalances; haemostasis etc.?
salicylates (eg aspirin)
NB salicylic acid is formed from aspirin acetylating COX
what class of drugs do ibuprofen and naproxen come under?
propionic acids
which class of drugs have very similar properties to propionic acids?
fenemates (eg mefenamic acid)
which drug is a good analgesic and antipyretic activity but is a poor anti-inflammatory; is a week COX inhibitor and is well-tolerated in the GIT?
paracetomol
what is the major issue with paracetamol?
hepatotoxitiy due to overdose (enzymes in the liver can become saturated and toxic metabolites form)
which type of drug is used for osteoarthritis and rheumatoid arthritis (also is restricted for use when traditional NSAIDs produce too sever GIT side effects) and is a selective COX-2 inhibitor?
coxibs eg celecoxib
