MSK - Drugs for Muscle Pain (including NSAIDs revision) COPY Flashcards
Compare and contrast the clinical actions of aspirin and ibuprofen.
Both aspirin and ibuprofen are:
(1) Anti-inflammatory
(2) Analgesic
(3) Antipyretic
Aspirin but NOT ibuprofen is an irreversible cyclo-oxygenase (COX) inhibitor and so a potent:
(4) Anti-platelet
What would be the usual analgesic choice for a child with mild to moderate pain?
Paracetamol would usually be the preferred first choice. Ibuprofen may be considered if greater anti-inflammatory action and analgesia is required.
Why does indometacin have a stronger anti-inflammatory profile than other nonselective NSAIDs?
Besides being a non-selective inhibitor of cyclo-oxygenase (COX), indometacin also inhibits phospholipase A2. Thus, indometacin reduces the production of leukotrienes, in addition to prostanoids, and so has a broader spectrum anti-inflammatory effect.
Which form of cyclo-oxygenase is expressed in inflammatory cells at sites of acute inflammation.
Inducible cyclo-oxygenase-2 (COX-2)
Why should etoricoxib be used with caution in a patient with active peptic ulcers?
Etoricoxib will impair wound healing and so pre-existing peptic ulcers are likely to persist.
What is the MOST common adverse effect of paracetamol at clinical analgesic doses?
Nausea
List THREE NSAIDs with greater selectivity for cyclo-oxygenase-2 (COX-2) over COX-1.
Etoricoxib, parecoxib (pro-drug of valdecoxib), celecoxib, meloxicam, mefenamic acid
Which NSAID has the greatest risk of precipitating an asthma attack in a patient with NSAID exacerbated respiratory disease (NERD)?
Aspirin because it is an irreversible inhibitor of cyclo-oxygenase (COX)
Which NSAIDs has the strongest anti-platelet effect?
Aspirin because it is an irreversible inhibitor of cyclo-oxygenase (COX)
What is the MOST common adverse effect of non-selective NSAIDs?
Nausea and other gastrointestinal adverse effects
What is the normal function of prostaglandins in the stomach?
Protective effects:
(1) Increase bicarbonate secretion
(2) Increase mucus secretion
(3) Increase blood flow to mucosa
(4) Decrease acid secretion
Why do NSAID-induced pseudoallergic reactions occur?
Inhibition of cyclo-oxygenase (COX) causes shunting of arachidonic acid to overflow into the 5-lipoxygenase pathway for the production of leukotrienes. Leukotrienes activate cysteinyl leukotriene receptors promoting mast cell degranulation and allergic responses.
At analgesic doses, what do ALL NSAIDs have in common?
At analgesic doses, all NSAIDs inhibit cyclo-oxygenase-2 (COX-2)
For what severity of pain are NSAIDs useful as analgesics?
NSAIDs are only useful for analgesics for mild to moderate pain. NSAIDs have an analgesic ceiling as they work as analgesics by preventing prostaglandin-mediated sensitisation of nociceptive fibres.
Explain why diclofenac is useful for the management of joint pain and inflammation.
Diclofenac accumulates in synovial fluid enabling a prolonged analgesic and anti-inflammatory at the joints while it has a relatively short plasma half-life and so fewer gastrointestinal adverse effects than other non-selective COX inhibitors.
Why are ALL NSAIDs contraindicated in late pregnancy?
All NSAIDs inhibit cyclo-oxygenase-2 (COX-2) at analgesic and anti-inflammatory doses. Inhibition of COX-2 risks premature closure of the ductus arteriosus. All NSAIDs are therefore contraindicated in the third trimester.
Which form of cyclo-oxygenase (COX) do platelets predominantly express?
Platelets express cyclo-oxygenase-1 (COX-1) which makes thromboxane-2 (TXA-2)
In general, COX-1 is constitutive and COX-2 is inducible but EXCEPTIONS include…
Expression of COX-2 in the kidney, synovial joints, CNS and female reproductive system.
The renal adverse effects of NSAIDs are due to inhibition of…
Both COX-1 and COX-2
List at least THREE renal adverse effects of NSAIDs?
Increased sodium retention, water retention following sodium retention, risk of hyperkalaemia, and changes in renal blood flow dynamics.
List at least FOUR NSAIDs ranked from most strongly antiplatelet to most strongly prothrombotic.
Aspirin > Ketoprofen > Indometacin > Naproxen > Ibuprofen >Piroxicam > Diclofenac > Mefenamic acid > Celecoxib > Parecoxib > Etoricoxib