Drugs for Muscle Pain Flashcards
What are the 3 kinds of drugs used in treating muscle pain?
- analgesics
- muscle relaxants
- adjuncts
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.
q
What is the MOST common adverse effect of paracetamol at clinical analgesic doses?
Nausea
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 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
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
Hepatoxicity of paracetamol (acetaminophen) overdose can be treated with…
N-acetyl-cysteine helps to treat paracetamol toxicity by replenishing glutathione, which detoxifies the toxic metabolites of paracetamol to nontoxic metabolites
The coxibs are markedly safer than non-selective NSAIDs for patients…
At risk of stomach ulcers
List at least THREE adverse effects of COX-1 inhibition
Increased risk of nausea and vomiting, gastro-oesophageal reflux, stomach ulcers, bruising/bleeding, renal adverse effects contributing to hypertension and fluid retention. (Note that COX-2 inhibition also contributes to renal adverse effects).
Name an NSAID available in a patch formulation suitable for lower back pain
Ketoprofen or diclofenac
Name TWO NSAIDs available in topical gel or cream formulations
Piroxicam, diclofenac, ketoprofen
State the mechanism of action of NSAIDs.
Inhibit COX1 and COX2 to prevent conversion of arachidonic acid to prostanoids (PGI2, PGE2, TXA2)
PGI2 - vasodilation, inhibit platelet aggregation, anti-coagulant
PGE2 - pain, vascular permeability
TXA2 - vasoconstriction, platelet aggregation, coagulant
State the selective and non-selective NSAIDs.
paiKIA NID CPE
Ketoprofen
Indomethacin
Aspirin
Naproxen
Ibuprofen
Diclofenac (avoid in liver disease)
COX2 only
Celecoxib
Parecoxib
Etoricoxib
State the common adverse effects of non-selective NSAIDS
- renal failure
- dyspepsia (GI)
- asthma
State the common adverse effects of COX selective NSAIDs
- nephrotoxicity
- impaired wound healing
- thrombosis
State the common contraindications for NSAIDs
- renal failure (eGFR <30ml/min)
- severe HF
- GI bleeding or ulcer
- bleeding disorders
- third trimester of pregnancy
- use of systemic corticosteroids/antiplatelet agents/anticoagulants