NSAIDS (Dr. Boston) Flashcards
NSAIDS general
Decrease pain, fever, inflammation
- Chronic Pain: Osteoarthritis
- Post operative pain
NSAIDS inhibit production of
Protaglandins (PG) from arachidonic acid cascade
- COX (cyclooxygenase) enzymes
Corticosteroids inhibit:
NSAIDs inhibit:
Corticosteroids inhibit: Phospholipase A
NSAIDS inhibit: Cyclooxygenase (COX)
Prostaglandin cascade from Membrane phospholipids
Membrane Phospholipids
=> broken down by Phospholipase A to…
Arachidonic Acid (AA)
=> broken down by COX to
Different prostaglandins
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Traditional (nonselective) NSAIDS
- Aspirin
- Piroxicam
Cox-1 enzymes
(Constitutive Prostaglandins)
- Housekeeping
- Protective effect on gastric mucosa
- Platelet function
- Renal blood flow
*not related to cell damage, pain, etc
COX-2 enzymes
(Inducible Prostaglandins)
- Pain
- Inflammation
- Fever
COX-1, COX-2 ratios
Selective
Non-selective
Selective: Ratio > 1 = preference for COX-2
- Carprofen (Rimadyl)
- Meloxicam
- Deramaxx
- not injectible
- Onsior
- FDA approved for cats, good for post-op pain
- Previcox (Firocoxib)
- horses
Nonselective: Ratio
- Ketoprofen
When NOT to prescribe an NSAID
1. Renal dz
2. Liver dz
3. GI dz
4. Risk of bleeding or low BP in sx
5. On corticosteroids
6. Cushingoid
Renal blood flow
- PGs maintain renal blood flow in hypotension (COX-1 > COX-2)
- Pre-operative use of NSAIDS
- Selective NSAIDs
- IV fluid support
- Blood pressure monitoring and support
Platelets
Thromboxane
- Thromboxane
- involved in clotting
- product of arachidonica acid metabolilsm
- COX-1 inhibition => platelets can’t produce thromboxane for 2-3 days
- Ketoprofen
- Piroxicam
- Selective NSAIDs probs ok
- metacam
- rimadyl
Aspirin
- Acetylates the COX enzyme irreversibly
- Platelets unable to synthesize more COX for the lifetime of the platelet
* NO SURGERY FOR 7-10 days
Perioperative use of NSAIDS
- Non-selective NSAIDs NOT RECOMMENDED
- COX-2 selective NSAIDS
- Rimadyl and Meloxicam - injectible
- No documented effects
- renal function
- platelet function
- Pre-operatively for preemptive analgesia
- Admin 30-60 minutes prior to recovery
Prostacyclin
Cox-2 dependant prostaglandin
prevents clots from forming intravascularly
Selective NSAIDs knock this out and predispose to clots
GI dz and NSAIDs
If vomiting diarrhea => stop NSAIDs
- Can cause perforating ulcer => peritonitis => death
Gastric Mucosal Protection
of constiuative house keeping prostaglandins
Inc mucus secretion
Inc Bicarbonate secretion
Inc Epithelial cell renewal
Inc Mucosal blood flow
Dec Acid secretion
Prostaglandins
In Gastric Mucosal Protection
Mostly COX-1
Nitric Oxide
Autonomic nervous system
PGE
Mast cell tumor and NSAIDs
Mast cells make Histamine
- Histamine (2 types)
- anaphylaxis type that induces swelling
- stomach protectant (decreases acidity)
Don’t know what’s going on in their stomach, if they have a lot of histamine and gastric ulcers
Also treat mast cells with corticosteroids and they don’t mix with NSAIDs
NSAID elimination
Metabolized in liver
Excreted in bile
Some productes excreted in kidneys
- Corticosteroids do not prevent production of ……
- Corticosteroids do inhibit….
3. Corticosteroids are not…
4. Corticosteroids do not inhibit…
5. Corticosteroids do cause….but…
- Prostaglandins
(another fatty acid besides Arachadonic Acid can be a precursor)
- Arachadonic Acid production
3. Analgesics
4. Platelet function
5. Gastrointestinal dysfunction but by a different mechanism than NSAIDs
-Can cause gastric ulceration
Leukotrienes
Produced from Lipoxygenase (LOX)
Inflammatory mediators
Gastrotoxic
-decrease circulation to the stomach
Corticosteroids overview
Glucocorticoids
- cortisol
Mineralocorticoids
- aldosterone
Cats and drug metabolism
Cats don’t metabolize drugs well
(b/c of their dec glucoronidation)
Cats and NSAIDs
- Prolonged elimination half-lives
- Many NSAIDs Except: Meloxicam
* cleared by oxidative enzymes in cats - No NSAIDs prescribed for long-term use in cats
- More sensitive to renal effects (dogs more sensitive to GI side effects)
* Monitor these cats’ chemistries
Acetaminophen contraindicated in cats
- Decreased glucuronidation => metabolism by alternate pathways
- Toxic Metabolite
- N-acetyl-p-benzoquinone
- Methemoglobinemia
- Heinz body anemia
- Detoxified by glutathione
- Antidote: Acetylcystein
- Glutathione precursor