Anti-inflammatory Pharm Flashcards
non pharmacological therapeutic options for inflammation
-rest, heat/cold, weight reduction, surgery
two pharmacological therapeutic options for inflammation
-NSAIDs
-glucocorticoids
three main benefits of NSAIDS
-anti-inflammatory effects
-anti-pyretic effects
-analgesic effects
what are prostaglandins required for and what are the synthesized from
-Prostaglandins (PGs) are required for normal homeostasis in all tissues
-They are synthesized from arachidonic acid by cyclooxygenase (COX) enzymes
what are the two main enzymes that prostaglandins are synthesized from
COX1 and COX2
how is COX1 normally present
normal housekeeping enzyme present at low levels in most tissues
how is COX2 normally present
normally present at much lower levels in most tissues but is important for homeostasis in a few tissues (renal medulla, gastric mucosa)
what COX is involved in healing gastric ulcers
COX2
what does thromboxane do
promotion of platelet aggregation
what does prostacyclin do
inhibition of platelet aggregation, vasodilation
what do other prostaglandins do
maintenance of tissue blood flow
what do PGE2 and PGI2 do in the stomach
they are involved in gastric mucosa protection (decreased acid secretion by gastric parietal cells, increased bicarb and mucus production, increased vasodilation)
what is the role of prostaglandins (eicosanoids) in inflammation
-COX2 is up-regulated in response to plasma membrane damage or inflammatory mediator release COX2 induction is a local response that occurs at the site of cell damage or mediator release = marked vasodilation occurs, promoting inflammation
what is phospholipase A2 stimulated by
cell membrane damage
what type of enzymes do NSAIDS inhibit
COX enzymes (both 1 and 2)
what is the effect of NSAIDS inhibiting COX enzymes (4)
-Reduces synthesis of PGs, including those that promote vasodilation
-Reduces blood flow to site
-Reduces sensitization of nociceptors
-Alleviates inflammation
what is the overall major benefit of NSAIDS
reduction of bloodflow to site of injury
what are the three main sites of adverse effects of NSAIDs
-gastric mucosa, platelets, kidney
what is the mechanism of adverse effects of the gastric mucosa
The normal protective effects of
PGs in the stomach are inhibited,
resulting in:
-Decreased blood flow, bicarb
secretion, & mucus secretion
-Increased acid secretion
=gastric bleeding +/- ulceration
(the most common adverse effect
associated with NSAIDs)
what is the most common adverse effect associated with NSAID use
gastric bleeding / ulceration
what is the mechanism of adverse effects of the platelets
Only COX1 is present in platelets NSAIDs inhibit the conversion of AA to thromboxane in platelets = result is a slightly increased general tendency to bleed
what is the mechanism of adverse effects of the kidney
-COX enzymes produce PGs that maintain adequate blood flow to many tissues, including the renal
medulla
-Excessive COX inhibition can lead to
renal medullary hypoxia & papillary necrosis
what is the outcome of NSAID use that inhibit COX2?
NSAIDs that preferentially inhibit COX2 (e.g., carprofen, etodolac, meloxicam, etc.) are associated with fewer episodes of gastric ulceration/bleeding, compared to non-selective blockers of COX1 & 2 (e.g., aspirin)
what are drugs that are selective for COX2 called
coxibs
pharmacokinetic properties of NSAIDS (4)
-Weak acids
-Highly protein bound
-Hepatic metabolism (Phase 2 conjugation)
-Variable elimination
shared adverse effects of NSAIDS (5)
-GI ulceration
-Inhibition of platelet aggregation = bleeding (most likely with aspirin)
-Inhibition of uterine motility
-Inhibition of PG-mediated renal perfusion
-Renal papillary necrosis in dehydrated animals (a problem with many NSAIDs)
clinical uses of NSAIDS
For the relief of musculoskeletal & inflammatory pain, including post-operative pain
contraindications of NSAIDS
As with all non-steroidal anti-inflammatory drugs (NSAIDs), administration of this drug is advised against in the following circumstances:
* Animals with gastro-intestinal ulcers, renal disease, hepatic
disorders, hypoproteinemia, dehydration, or cardiac disease;
* A known hypersensitivity to the drug;
* Concurrent use of other NSAIDs or corticosteroids.
what is the only NSAID that blocks COX enzymes irreversibly?
aspirin
in vitro vs in vivo effects of aspirin inhibition
In vitro it is a non-selective inhibitor of COX 1 & 2, but in vivo it acts mainly to inhibit COX 1
what species is aspirin approved in
cattle and horses
is the therapeutic margin wide or narrow for aspirin
narrow