NSAID Flashcards
Describe enzymes NSAIDs work on
Membrane lipids are converted to arachadonic acid via phospholipase A. Then AA is converted into prostaglandins via COX (cyclooxygenase)
Describe the MOA of NSAIDs
Inhibit PG production by inhibiting COX enzyme
COX1 - functions
Constitutive PG - housekeeping, GI protection, platelet function, renal blood flow
COX2 functions
Inducible PG - pain, fever, inflammation
Describe COX1 effect on platelets
Decreases synthesis of thromboxane which is necessary for platelet aggregation via competitive inhibition. Can last 2-3 days.
Type of NSAID- meloxicam
Selective
Type of NSAID- ketoprofen
Non
Type of NSAID- aspirin
Non
Type of NSAID- firocoxib
Selective
Type of NSAID- Carprofen
Selective
Type of NSAID- Deracoxib
Sel (deramaxx)
Type of NSAID- prioxicam
Non
Type of NSAID- robenacoxib
Sel (onsior)
Aspirin- MOA
Irreversible acetylation of COX1, effect on platelets for 7-10 days (life of platelet)
Define IC50
amount of drug needed to inhibit 50% of each enzyme; >1 = selective,
Contraindications of NSAIDS
Renal dz, liver dz, GI dz, mast cell tumors, corticosteroids, surgery, cushing’s, cats
Describe metabolism of NSAIDs
Liver metabolism via glucuronidation (or oxidative enzyme)
NSAID elimination
Urine or bile excretion of metabolites
Why are NSAIDs contraindicated in kidney disease
PGs from COX1 maintain blood flow in hypotension
Why are NSAIDs contraindicated in GI dz
Inhibit PGE production which protects mucosa
What drug can be given with NSAIDs to protect GI
Misoprostol (synthetic PGE)
How can NSAIDs cause gastritis
Decreased mucosal blood flow and increased neutrophil adherance to vasculature
Why are mast cell tumors contraindication
Histamine is a GI protectant
Why are NSAIDs contraindicated in corticosteroid use
Corticosteroids decrease GI health via other mechanism, so additive effect will be worse
Type of NSAID- tepoxalin
Non selective- Dual COX/LOX inhibitor- inhibition of LOX decreases GI effects bc leukotrienes are gastrotoxic
Why are NSAIDs contraindicated in cats
Less glucuronidation leading to elongated half life of elimination
NSAID side effects- cats vs dogs
Cats- renal Dogs- GI
Which NSAID is cleared by oxidative enzymes
Meloxicam in cats
What drug can lead to methemoglobinemia in cats
Acetaminophen - toxicmetabolite NaPb
What is the antidote to acetaminophen in cats
acetylcysteine - a glutathione precursor which detoxifies
Which NSAIDs are best for perioperative use, why?
Inj rimadyl and meloxicam, no effect on platelets
When should NSAIDs be given around sx and why
30-60 min prior to recovery to give time to eliminate existing prostaglandins
