Refer to our full advice first
If you’ve not done so already, refer first to our full advice on morphine and opioid switching included in this series.
Scenario: morphine to oxycodone switch
Patient is taking modified-release morphine tablets at a dose of 30mg twice daily with morphine oral solution at a dose of 10mg 4 hourly when required (‘prn’) for breakthrough pain (patient reports needing to take this on average twice daily). Their consultant suggests to switch morphine to oxycodone.
The steps below provide an example of how a healthcare professional may apply Switching between oral morphine and other oral opioids in adult palliative cancer care patients to determine the appropriate dose of oxycodone to prescribe in this scenario.
- Modified-release morphine: 30 x 2 = 60mg
- ‘prn’ morphine: 10 x 2 = 20mg
Total daily morphine dose = 60 + 20 = 80mg
From the equivalence information in our tool (morphine to oxycodone), advice is to divide total daily dose morphine by 1.5 to 2.
80mg ÷ 1.5 = 53mg
80mg ÷ 2 = 40mg.
Approximate equivalent total daily dose of oral oxycodone is therefore 40mg to 53mg.
As advised in our main article, a dose reduction is often recommended. Read the full advice to decide whether or not to apply a dose reduction, and if so, how much.
For a 25% dose reduction:
0.25 x 40mg = 10mg (40mg – 10mg = 30mg)
0.25 x 53mg = 13.25mg (53mg – 13.25mg = 39.75mg)
Resulting total oxycodone daily dose: 30mg to 39.75mg.
Prescribe for regular use at a dose as close as possible to the calculated total daily dose in suitable divided doses (as recommended in the BNF or SmPC)
e.g. oxycodone modified-release tablets 15mg twice daily (total daily dose of 30mg).
Consult BNF or SmPC to choose an appropriate ‘immediate-release’ preparation and check usual dose recommendations.
Scottish Palliative Care Guidelines: Choosing and Changing Opioids advise an appropriate ‘as required’ (‘prn’) dose is typically one-sixth to one-tenth of the total daily dose (1/6 x 30 = 5mg).
e.g. oxycodone oral solution 5mg every 4 hours when required for breakthrough pain
As advised in our main article, following conversion, the patient should be monitored and doses gradually titrated up or down depending on response and side effects.
This includes regular doses as well as ‘prn’ doses for breakthrough pain.
- Minor amendments following user feedback