Musculoskeletal Drugs and Analgesics Flashcards
List the 3 main types of opiate analgesia.
Codeine
Morphine
Oxycodone
Describe the mechanism of action of opiates/opioids. (2)
- Opioid receptor agonist: acts on mu, kappa and delta receptors on presynaptic neurons
- This increases nociceptive thresholds throughout CNS and PNS
List 3 indications for codeine.
List 3 indications for morphine.
List 3 indications for oxycodone.
CODEINE:
Mild-moderate pain
Persistent dry cough
Diarrhoea
MORPHINE:
Acute severe pain (incl. MI)
Acute pulmonary oedema
Chronic pain
OXYCODONE:
Moderate-severe pain in cancer
Post-op pain
Severe pain
List 5 side effects of codeine.
Nausea Vomiting Constipation Biliary spasm Headache (on withdrawal)
Describe the important pharmacokinetics/dynamics of codeine. (4)
Metabolised to morphine
Liver metabolism
Active metabolites excreted in urine (can accumulate in renal failure)
10% of population resistant to codeine (due to lack of demethylating enzyme which converts it to morphine)
What would you tell the patient when prescribing codeine? (2)
Can be taken with paracetamol
Constipation is common
List 6 side effects of morphine.
Nausea Vomiting Abdominal pain Constipation Respiratory depression Sedation
Describe the important pharmacokinetics/dynamics of morphine. (3)
Liver metabolism
Active metabolites can accumulate in renal failure
Accumulation can cause respiratory/CNS depression
What would you tell the patient when prescribing morphine? (1)
Often given with anti-emetic to reduce N/V
List 4 side effects of oxycodone.
Nausea
Vomiting
Abdominal pain
Constipation
Describe the important pharmacokinetics/dynamics of oxycodone. (3)
What would you tell the patient when prescribing oxycodone? (1)
PHARMA:
Long/short acting preparations available
Liver metabolism
Admin: often slow IV/subcut infusion
PATIENT INFO:
Nausea and constipation are common
What are the 2 types of NSAID?
Give some examples of each.
Non-selective NSAIDs, e.g.
- Ibuprofen
- Diclofenac
Selective NSAIDs, e.g.
-Celecoxib
Describe the mechanism of action of NSAIDs.
What is the difference between non-selective and selective NSAIDs? What is the advantage of selective NSAIDs?
- Inhibition of cyclo-oxygenase (COX 1/2) enzymes
- This inhibits prostaglandin synthesis
a. This decreases pain, inflammation and
swelling
DIFFERENCE:
Non-selective: inhibit COX 1 and 2
Selective: only inhibit COX2 (WHY? GI side effects caused by COX1)
List 3 indications for non-selective NSAIDs.
List 3 indications for selective NSAIDs.
NON-SELECTIVE:
Mild-moderate pain relief
Rheumatic disorders
Fever
SELECTIVE:
Osteoarthritis
RA
Ankylosing spondylitis
List 6 side effects of NSAIDs.
Gastric/duodenal ulceration Nausea Diarrhoea Thrombotic events Renal impairment Hyperkalaemia
Describe the important pharmacokinetics/dynamics of non-selective NSAIDs. (3)
Avoid in:
- Pregnancy
- Renal impairment
Caution in:
-Elderly (risk of GI bleeds)
What would you tell the patient when prescribing NSAIDs? (4)
Risk of GI bleeds on long term use
Take with food/milk
Take only when needed
Give PPI with NSAIDs (not needed with selective NSAIDs)
Describe the important pharmacokinetics/dynamics of selective NSAIDs. (5)
Lower incidence of serious GI bleeds
Higher risk of CVD events
Avoid in:
- Renal impairment
- Pregnancy
Caution in:
-Elderly
Describe the mechanism of action of paracetamol. (2)
- Weak cyclo-oxygenase (COX) inhibitor, selective for brain COX
- Lacks peripheral anti-inflammatory actions but inhibits prostaglandin synthesis in CNS
List 2 indications for paracetamol.
Mild-moderate pain relief
Fever
List 2 side effects of paracetamol.
Rash
Blood disorders
Describe the important pharmacokinetics/dynamics of paracetamol. (2)
What would you tell the patient when prescribing paracetamol? (1)
PHARMA:
Avoid overdose - causes severe liver damage
Reduce dose to 500mg every 4 hours in patients <50kg
PATIENT INFO:
Avoid other OTC medications containing paracetamol
Give 1 example of an xanthine oxidase inhibitor.
Allopurinol
Describe the mechanism of action of allopurinol. (2)
- Reduces synthesis of uric acid by competitively inhibiting xanthine oxidase
- Reduces serum uric acid levels
List 3 indications for allopurinol.
Gout
Calcium oxalate kidney stones
Hyperuricaemia associated with chemotherapy
List 4 side effects of allopurinol.
Rash
Hypersensitivity
GI upset
Neutropenia
Describe the important pharmacokinetics/dynamics of allopurinol. (3)
Do NOT start during acute attack (can exacerbate it)
CYP450 inhibitor
Affects azathioprine metabolism
What would you tell the patient when prescribing allopurinol? (4)
Rash/GI upset relatively common
Rash should be reported to doctor
Keep taking allopurinol even with no symptoms
Often given with NSAID or colchicine
