4. Pain and inflammation Flashcards
NSAIDs mechanism of action
Block cycloxygenase enzymes which are involved in prostaglandin synthesis. Prostaglandins are made at sites of tissue damage, and cause inflammation pain and fever
Types of NSAIDs
- Non selective (diclofenac, aspirin, ibuprofen, naproxen, indometacin ect)
- COX-2: Celecoxib, etoricoxib, parecoxib
COX-2 selective NSAIDs are identified as having -COXIB at the end of the
NSAIDs side effects
- Asthma and dysnopnoea
- NSAID hypersensitivity: asthma attack, urticaria, rhinitis
CAUTION in patients with allergies - Photosensitivity (topical) - patients must avoid excessive sunlight exposure
- Nephrotoxic (as they constrict the renal afferent arteriole -> reduces renal blood flow -> lowers eGFR)
CAUTION in dehydrated patients as this is a risk factor for AKI, vomiting, diarrhoea,
Examples of nephrotoxic drugs
- NSAIDs
- ACE inhibitors and ARBs
- Diuretics
NSAIDs side effects
- oedema - increase sodium and water retention
- hypertension - due to increased blood volume, from raised sodium and water retention
CAUTION in patients with uncontrolled hypertension - bleeding - due to COX enzymes and platelets being blocked
- hyPERkalaemia due to increase sodium and water retention
Examples of NSAIDs gastro-intestinal toxicity
and suitable counselling offered
All NSAIDs cause gastro-intestinal toxicity. NSAIDs should be taken with or after food. Alternatively, enteric coated formulations can be offered
GI bleeding
Peptic ulcers
Perforation
Enteric coated formulations dissolve in the intestinte instead of the st
Non-selective NSAID GI contra-indications
Non-selective NSAIDs are contraindicated if
they have previously cause an ulcer or bleeding
OR
if they have caused at least TWO recurrent episodes of GI toxicity
Which non-selective NSAIDs cannot be given to a patient with a history of a gastro-intestinal ulcer or bleeding even if it wasnt caused by an NSAID, as they have the highest risk of gastro-intestinal toxicity
Ketoprofen, Ketorolac, Piroxicam
High risk drugs for gastro-intestinal toxicity
High risk: Ketoprofen, Ketorolac, Piroxicam
intermediate risk: Naproxen, Diclofenac, Indometacin
Low risk drugs for gastrointestinal toxicity
COX-2 selective inhibitors, ibuprofen <1.2g BUT are associated with the highest risk of cardiovascualar events
NSAIDs and cardiovascular events
All NSAIDs are asocciated with a small increased risk for thrombotic events like a heart attack or stroke
Can cause heart failure. CONTRAINDICATED in severe heart failure
NSAIDs which have the highest risk for cardiovascular events
High dose ibuprofen 2.4
Diclofenac 150mg daily/Aceclofenac
therefore have more contraindications
contraindicated in
* mild heart failure, ischaemic heart disease (angina), cerebrovascular disease (TIA, stroke), peripheral vascular disease
NSAIDs and pregnancy
AVOID especially in the third trimester
can delay, prolong labour
can cause pulmonary hypertension in the baby
NSAIDs interactions
-
Interacts with nephrotoxic drugs:
aminoglycosides, cephalosporin, glycopeptide, ciclosporin, tacromilus, methotrexate -
interacts with drugs that are cleared renally as NSAIDs reduce eGFR
Lithium, methotrexate -
interacts with drugs that increase bleeding
anticoagulants, alcohol, antiplatelets, corticosteroids, SSRI’s, venlafaxine
(warfarin and NSAIDs are highly protein bound drugs. NSAIDs displace warfarin from the proteins = increases the free conc of warfarin = bleeding) -
interacts with drugs that cause hyperkalaemia
ACE inhibitors, ciclosporin, tacrolimus, heparin, potassium-sparing diuretics, trimethoprim - can induce convulsions in patients taking quinolone antibiotics
Migraine treatment
Acute
1st line: Oral triptan
2nd line: NSAIDs or paracetamol and can be used in combination with triptans
Prevention
1st line: propanol
2nd line: topiramate, amitryptiline
