NSAIDs Flashcards
Define eicosanoid and list four major classes
Inflammatory mediators
Classes: \+Prostaglandins \+Prostacyclin \+Thromboxanes \+Leukotrienes
Describe the synthesis of eicosanoids via the COX and LOX pathways
With stimulus (injury or inflammation),
Phospholipids are metabolized by PLA2 into arachidonic acid
COX will turn this into PGs, prostacyclin, and thromboxanes
LOX will turn into leukotrienes
What receptor does prostacyclin (PGI2) act on?
IP
What receptor does PGE2 act on?
EP 1-4
What receptor does thromboxane act on?
TP alpha
TP beta
Compare and contrast the functions of COX1 and COX2
COX1
+constitutively expressed
+dominant source of prostanoids for housekeeping functions (gastric cytoprotection, maintenance of kidney function)
COX2
+induced by cytokines, tumor promoters
+important source of eicosanoids in inflammation and cancer
How do PGE2 and PGI2 affect vascular smooth muscle?
Gs pathway
= inc. cAMP
= vasodilation (+ more blood flow)
= more vascular permeability
What effect does TXA2 have on vascular smooth muscle?
Activate Gq
= inc. Ca
= vasoconstriction
What factors can stimulate free nerve endings to be interpreted as pain?
PH changes
Heat
Inflammation
Differentiate between Adelta and C fibers
A-delta = myelinated
= faster transduction
= sharp pain
C fibers = no myelin
= slow travel
= throbbing pain
How is it that PGE2 and PGI2 sensitize afferent nerves to pain?
PGs are pain modulators - they can reduce threshold of pain
How do PGI2 and TXA2 compare in their influence toward platelet aggregation?
TXA2 promotes platelet aggregation
PGI2 inhibits platelet aggregation
What are the effects of PGE2 and PGI2 on kidneys?
Vasodilation
=maintain RBF + GFR
PG induced inhibition of NaCl reabsorption
What is the effect of eicosanoids on the lungs?
Bronchoconstriction
Leukotrienes
What are the effects of eicosanoids on pregnancy?
Increase during labor
Maintain ductus arteriosus
Inc. uterine tone
Describe the MOA of NSAIDs
Inhibit production of PGs by competing with arachidonic acid for binding in COX catalytic site
What is the mechanism behind
Anti-inflammatory
Action of NSAIDs?
Prostanoids (PGE/PGI) significantly increase in inflamed tissue
= blood flow to these sites will worsen inflammation
=vascular permeability inc.
=more leukocyte infiltrate