Block 4 W3 Flashcards
Give examples of immune driven inflammation.
Allergies Graft vs. Host disease Autoimmune disease Contact dermatitis Celiac disease
What is arachidonate acid formed from?
Cellular phospholipid bilayer by phospholipase A2.
Metabolised by cyclooxygenase into prostaglandins and prostacyclin, thromboxane.
What is the role of prostacyclin, PGI2?
Vasodilator, hyperalgesic, stops platelet aggregation.
What is the role of thromboxane, TXA2?
Thrombotic, vasoconstrictor.
What is the role of prostaglandin, PGF2a?
Bronchoconstrictor, myometrial contraction.
What is the role of prostaglandin, PGD2?
Inhibits platelet aggregation and vasodilator.
What is the role of prostaglandin, PGE2?
Vasodilator and hyperalgesic.
Define NSAIDs and give examples.
Non-steroidal anti-inflammatory drugs
e.g. aspirin, ibuprofen, diclofenac
Prescribed for pain and chronic inflammation - minor aches and pains.
What are the 3 major effects of NSAIDs?
- Anti-inflammatory - blocks COX from making prostaglandins which regulate inflammation due to vasodilation and increased vessel permeability.
- Analgesic - prostaglandins sensitises spinal neurones to pain.
- Antipyretic - prostaglandin synthesis inhibited in hypothalamus so reduces firing rate that control thermoregulation.
Describe the mech of action of aspirin.
Irreversibly inactivates both isoforms of COX (1 and 2) by acetylating the catalytic serine residue in position 529.
Affects COX2 expression at both transcriptional and post-t level.
What does low dose aspirin do?
Preferentially affects thromboxane pathway -> reduced platelet aggregation.
What does high dose aspirin do?
Affects both pathways -> risk of bleeding as inhibits prostacyclin, required for inhibition of platelet aggregation.
How does ibuprofen interact with aspirin?
Block the anti-platelet effects.
What are the side effects of aspirin?
Deaf, swelling of eyes, face, lips, tongue, wheezing, cold clammy hands, hives, nausea, tachycardia, bloody stools, and vomit.
What do 2nd generation NSAIDs target?
Selective COX2 inhibitors
e.g. Coxibs
Minimised gastric problems but targeted prostacyclin which increased risk CVD.
Define NO-NSAIDs?
Nitric oxide - donating NSAID
have gastro-protective effect and increased anti-inflammatory activity.
What are the adverse events of NSAIDs caused by?
Inhibition of COX1 - useful as a housekeeping role.
What are the adverse side effects of NSAIDs?
- Abdominal discomfort, dyspepsia - reduced PG synthesis in GI -> increased gastric acid secretion, diminished mucus secretion so acid irritates GI lining.
- Stomach/duodenal ulceration - PG normally causes mucus release so NSAIDs blocks this.
- MI - COX1 expressed in endothelium -> pre-disposes to blood clots and high BP.
Define SAIDs.
Steroidal anti-inflammatory drugs -> glucocorticoids
e.g. hydrocortisone, prednisone, dexamethasone
Synthesised from cholesterol.
Used in inflammatory diseases.
Reduces phospholipase A, COX2 thus reducing prostaglandins.
What are the side effects of SAIDs?
Occurs with prolonged systemic use.
- suppresses IR
- suppresses endogenous glucocorticoid synthesis
- iatrogenic Cushing’s syndrome
- osteoporosis.
How does histamine produce the Lewis Triple response?
- reddening - vasodilation
- wheal - increased permeability
- flare - antidromic stimulation of local nerves
What is the effect of histamine systemically?
- stimulation of gastric secretion
- contraction of smooth muscle
- cardiac stimulation
- vasodilation
- increased vascular permeability
Give examples of sedating anti-histamines.
Chlorphenamine and promethazine
Give examples of non-sedating anti-histamines.
Cetrizine and fexofenadine.