Pain management in palliative care

Question 1

What are the diffrent drugs used in each step of the WHO pain ladder?

Answer 1

Step 1 (non-opioid analgesia):

• Paracetamol
• NSAIDs

Step 2 (weak opioids):

• Codeine
• Dihydrocodeine
• Tramadol

Step 3 (strong opioids):

• Morphine
• Dimorphine
• Fentanyl
• Alfentanyl
• Buprenorphine

Question 2

How are doses of weak opioids (e.g. codeine) converted to oral morphine?

Answer 2

24hr dose of oral morphine = 24hr dose of codeine ÷ 10

Question 3

What are the different formulations of oral morphine and how are the two converted between?

Answer 3

• Morphine sulfate immediate release (Oromorph) effect lasts for 4hrs
• Morphine sulfate modified release (MST) effect lasts for 12hrs
• In patients who have been just taking oromorph, total dose over 24hrs is divided by 2 to determine the dose of MST needed to be given per dose BD (e.g. if patient takes 40mg oromorph over 24hrs, they should be given 20mg MST BD to gain the same effect)

Question 4

How is dosage of oral morphine determined for breakthrough pain?

Answer 4

Breakthrough pain = Dose in 24hrs ÷ 6

Question 5

What is the stepwise approach to initiating strong opioids from weak opioids or from scratch?

Answer 5

1. The 24hr dose of oromorph should be calculated either from the 24hr dose of weak opioids, or 15mg/24hrs if starting from scratch
2. This should then be divided by 6 to determine the dose that should be given 4-hourly, with same doses given PRN if pain control insufficient
3. Once total 24hr dose of morphine needed for pain control is determined, switch to BD administration of MST morphine

Question 6

How are doses of oral morphine converted to subcutaneous morphine or diamorphine

Answer 6

• 24hr dose of morphine SC = 24hr dose of morphine PO ÷ 2
• 24hr dose of diamorphine SC = 24hr dose of morphine PO ÷ 3

Question 7

How is dosage of morphine SC and diamorphine determined for breakthrough pain?

Answer 7

Divide 24hr doses by 6

Question 8

What are the prominent side-effects of morphine?

Answer 8

1. Constipation
2. Nausea
3. Vivid dreams
4. Visual hallucinations
5. Cognitive slowing
6. Drowiness/coma
7. Myotonic jerks
8. Respiratory depression

Question 9

What laxatives need to be prescribed with morphine?

Answer 9

Stimulant laxative (e.g. senna, bisacodyl) + stool softener (e.g. docusate, glycerol)

Question 10

What anti-emetic needs to be prescribed with morphine?

Answer 10

Haloperidol for morphine-induced nausea & vomiting

Question 11

What are the drugs used to treat neuropathic pain?

Answer 11

• Amitriptyline
• Pregabalin
• Gabapentin

Question 12

How should intestinal colic be treated?

Answer 12

Hyoscine butylbromide (anti-spasmodic)

Question 13

How should bone pain be managed?

Answer 13

• Standard analgesia
• Palliative radiotherapy
• Bisphosphonates may be effective against lytic bone lesions, but not sclerotic lesions

Question 14

How are doses of oral morphine converted to oxycodone?

Answer 14

24hr dose of oral oxycodone = 24hr dose of oral morphine ÷ 1.5

Question 15

What are the different formulations of oxycodone?

Answer 15

• Oxynorm (short-acting) effect lasts for 4hrs
• Oxycontin (long-acting) effect lasts for 12hrs

Question 16

How are doses of oral oxycodone converted to subcutaneous oxycodone?

Answer 16

24hr dose of S/C oxycodone = 24hr dose of oral oxycodone ÷ 1.5

Question 17

How are doses of oral morphine converted to alfentanyl?

Answer 17

24hr dose of alfentanyl = 24hr dose of oral morphine ÷ 30 or 24hr dose of diamorphine ÷ 10

Question 18

Which analgesics are safe to use in patients with renal failure and which are not?

Answer 18

Step 2:

• Avoid codeine
• Tramadol can be used with caution

Step 3:

• Avoid morphine, diamorphine and oxycodone
• Fentanyl or alfentanyl can be used

Question 19

Summary of strong opioid conversions

Answer 19