Musculoskeletal and Pain Drugs Flashcards
give some examples of opiates?
codeine
morphine
oxycodone
what is the MoA for codeine and morphine and oxycodone?
Opioid receptor agonist; acts on mu, kappa and delta on presynaptic neurones. This gives numerous effects that increase nociceptive thresholds throughout the CNS and PNS.
what are the indications for codeine?
Mild to moderate pain
Persistent dry cough
Diarrhoea
list some side effects of codeine:
Nausea Vomiting Constipation Biliary spasm Headache on withdrawal
what is important clinically regarding pharmacokinetics/dynamics for codeine?
Metabolised to morphine which is responsible for analgesic effects.
Predominantly metabolised by the liver.
Active metabolites are excreted in the urine so can accumulate in renal failure.
10% of population resistant to codeine’s analgesic properties as they lack the demethylating enzyme that converts it to morphine
what info should be given to patient before starting on codeine?
Can be taken with paracetamol for a better analgesic effect.
Constipation is a likely side effect.
what are the indications for morphine?
Acute severe pain (including in setting of myocardial infarction)
Acute pulmonary oedema
Chronic pain
what are some side effects of morphine?
Nausea Vomiting Abdominal pain Constipation Respiratory depression Sedation
what is important clinically regarding pharmacokinetics/dynamics for morphine?
Predominantly metabolised by the liver.
Metabolites are active and can accumulate in renal failure.
Accumulation can result in respiratory and CNS depression.
what info should be given to patient before starting on morphine?
Often given with an anti-emetic to reduce nausea / vomiting.
what are the indications for oxycodone
Moderate to severe pain relief in cancer patients
Postoperative pain
Severe pain
list some side effects of oxycodone:
Nausea
Vomiting
Abdominal pain
Constipation
what is important clinically regarding pharmacokinetics/dynamics for oxycodone?
Available as long and short acting preparations
Predominantly metabolised by the liver.
Often administered via slow intravenous/subcutaneous infusion.
what info should be given to patient before starting on oxycodone?
Nausea and constipation are common side-effects.
give examples of non selective NSAIDs?
ibuprofen
diclofenac
what is the MoA of non selective NSAIDs?
Non-selective inhibition of cyclo-oxygenase (COX 1 and 2) enzymes, decreasing key inflammatory mediator prostaglandin from being synthesised.
Thereby reduces pain, inflammation and swelling.
what are the indications for non selective NSAIDs?
Mild to moderate pain relief
Rheumatic disorders (such as rheumatoid arthritis and osteoarthritis)
Fever (anti-pyretic effect)
list some side effects of non selective NSAIDs?
Gastric and duodenal ulceration
Nausea
Diarrhoea
Small increased risk of thrombotic events even when used short term, particularly diclofenac and high dose ibuprofen.
Avoid in pregnancy particularly 3rd trimester (risk of closure of fetal ductusarteriosus in utero and pulmonary hypertension in newborn)
Renal impairment
Hyperkalaemia
what is important clinically regarding pharmacokinetics/dynamics for non selective NSAIDs?
Pain relief starts soon after the first dose, full analgesic effects can take up to one week and anti-inflammatory effects can take up to three weeks.
Avoid in patients with renal impairment – use lowest dose, for shortest time if unavoidable.
Caution should be used in the elderly – risk of gastrointenstinal bleeds.
what info should be given to patient before starting on non selective NSAIDs?
Risk of stomach bleeds if on long-term use.
Take with food or milk, to reduce abdominal discomfort and to reduce the risk of bleeding.
Take only when required.
In elderly patients a proton pump inhibitor is usually given alongside NSAID drugs
what are some examples of selective NSAIDs?
Celecoxib
what is the MoA for selective NSAIDs?
Selective inhibitor of COX-2, decreasing key inflammatory mediator prostaglandin from being synthesised.
Thereby reduces pain, inflammation and swelling.
The gastrointestinal side effects are mediated via COX-1 inhibition
what are the indications for selective NSAIDs
Pain and inflammation in: osteoarthritis / rheumatoid arthritis / ankylosing spondylitis
list some side effects of selective NSAIDs?
Gastric and duodenal ulceration (Risk increases with duration of therapy and dosage) Nausea Diarrhoea Renal impairment Hyperkalaemia
what is important clinically regarding pharmacokinetics/dynamics for selective NSAIDs?
Less incidence of serious GI bleeds / ulceration compared to non-selective.
Presumed higher risk of CV events, compared to non-selective.
Avoid in patients with renal impairment – use lowest dose, for shortest time if unavoidable.
Caution should be used in the elderly – risk of GI bleeds.
Avoid in pregnancy particularly 3rd trimester
what info should be given to patient before starting on selective NSAIDs?
Risk of stomach bleeds if on long-term use.
Take with food or milk, to reduce abdominal discomfort and to reduce the risk of bleeding.
Take only when required.
what is the MoA for paracetamol?
A weak cyclooxygenase enzyme (COX) inhibitor with selectivity for brain COX.
It therefore lacks peripheral anti-inflammatory actions but is useful in increasing the threshold for nociceptive activation by inhibiting prostaglandin synthesis and its effects centrally.
what are the indications for paracetomal
Mild to moderate pain relief
Fever (anti-pyretic effect)
list some side effects of paracetamal
Rash / blood disorders
what is important clinically regarding pharmacokinetics/dynamics for paracetamol
Overdose must be avoided – severe liver damage can occur and can be fatal.
Careful dosing in younger patients and patients with low body weight (reduce dose to 500mg 4-6 hourly, qid in patients <50kg)
what info should be given to patient before starting paracetamol?
Take only the prescribed amount and be wary of other over-the-counter medications that may contain paracetamol.
what is an example of a xanthine oxidase inhibitor?
allopurinol
what is the MoA for allopurinol?
Reduces synthesis of uric acid by competitively inhibiting xanthine oxidase.
Reduces serum uric acid level
what are the indications for allopurinol?
Prophylaxis of gout
Prophylaxis of calcium oxalate renal stones
Hyperuricaemia associated with cancer chemotherapy
list some side effects of allopurinol:
Rash
Hypersensitivity
Gastrointestinal disturbances
Neutropenia (rare)
what is important clinically regarding pharmacokinetics/dynamics for allopurinol?
Not used to treat acute attack of gout, can exacerbate the inflammation, so should not be started during acute episodes.
Cytochrome P450 enzyme inhibitor
Azathioprine metabolism affected.
what info should be given to patient before starting allopurinol?
Rash and abdominal disturbances are relatively common. - report to Dr.
Keep taking allopurinol, even when there is no sign of gout.
In order to prevent an exacerbation of gout a NSAID or cochicine is often prescribed for the first 3 months of therapy
