Seek specialist advice if uncertain

• These doses/ratios are approximate (≈) and not exact equivalent doses and should be used as a guide.
• Dose conversions should be conservative and doses are usually rounded down (Note – check available strengths).
• Adjust and monitor doses closely, extra care with: opioid toxicity; frail and elderly patients; renal or hepatic impairment.
• Always prescribe an appropriate drug and dose for breakthrough pain:
• 1/6th to 1/10th of the 24 hour regular opioid dose as required.

Tables are best viewed in landscape mode on mobile devices

* Not generally recommended for use in palliative care.

** Note buprenorphine is measured in micrograms and morphine is measured in milligrams.

*Use only with specialist palliative care input

Dose Conversions

A guide to dose conversions FROM morphine TO second-line opioid analgesics used for moderate to severe pain

Use the tables above as a guide. The doses are approximate (≈) and not exact equivalent doses. Breakthrough opioid doses are based on a calculation of 1/6th of the daily dose - these doses may be adjusted up or down to avoid the use of decimal points and to allow a practical dose to be administered. Some patients may require a smaller 4-hour breakthrough dose of 1/10th of the daily dose. Initiate dose with caution depending on clinical condition and judgement.

• Opioid bioavailability (particularly for oral morphine) and response are highly variable.
• It is important to exercise caution when switching opioids. Start low and titrate gradually.
• Always prescribe an appropriate drug and dose for breakthrough pain: 1/6th to 1/10th of the 24 hour regular opioid dose as required.
• Opioid conversions and ratios may vary depending on the resource used. The conversions used in these guidelines are based on consensus of use across Scotland and reference sources.
• Consider reducing the dose by up to 30% and re-titrating:
  • when changing opioid because of differences in pharmacokinetics and pharmacodynamics, including incomplete cross tolerance
  • if the patient is opioid toxic, frail or elderly.
• Check the information about individual drugs if the patient has renal or liver impairment.
• Particular care is needed when changing between opioids at higher doses or when the dose of the first opioid has been rapidly increased as these patients are at greater risk of adverse effects.
• Morphine and oxycodone doses can be measured accurately in 1mg dose increments. Decimal places are not recommended.
• Fentanyl: Refer to Fentanyl Patches information sheet for dose conversions.
• Alfentanil: Refer to Alfentanil information sheet for dose conversions.
• The effective sublingual/buccal dose of Fentanyl cannot be reliably predicted from the background maintenance opioid dose and individual titration for a patient is required, always starting at the lowest dose.
• Monitor the patient carefully. If in doubt, seek advice.

• Patients on a regular opioid will require an opioid prescribed as required for breakthrough pain. An appropriate as required dose is typically 1/6th to 1/10th of the regular opioid dose.
• The as required dose is usually increased appropriately when the dose of regular opioid is increased.
• For most as required opioids a prescribing interval equivalent to the duration of expected onset of action for the route administered is permitted, particularly if pain is severe to allow for dose titration whilst monitoring for toxicity. The prescription should also identify that if 3 or more doses have been given within 4 hours with little or no benefit urgent advice or review should be sought.  If more than 6 doses are required in 24 hours advice or review should be requested.
• Refer to Care in the last days of life guideline.
• Seek specialist advice when prescribing rapid acting fentanyl preparations or refer to the medicine information sheet if familiar with the product - Fentanyl sublingual (Abstral)®, Fentanyl buccal (Effentora)® and Fentanyl nasal spray (PecFent)®.