morphine to fentanyl patch conversion
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24 hourly oral morphine (mg) fentanyl patch (mcg/hour)
30 12
60 25
120 50
180 75
240 100

 

The table has been derived from the data sheet, and simplified to match available preparations. When converting, because the patches cover a range of equivalent oral morphine doses, it is usually safer to choose an initial dose at the lower end of the equivalent dose range plus breakthrough analgesia.

Doses given in the table are approximations for guidance only and should always be titrated to the individual patient's requirments.

Notes:

  • dose of fentanyl delivered is proportional to the patch size, ie '25' patch delivers 25 mcg of fentanyl per hour
    • after application of the first patch, plasma levels rise for 24 hours, analgesic levels are reached by 6-12 hours and a steady state is reached by the time of application of the second patch
    • the patch should be replaced every 3 days
    • on removal, a depot of fentanyl remains in the skin for 24 hours, falling by 50% after 17 hours
    • currently 12 microgram patches are only licensed for titration of doses, rather than initiating transdermal fentanyl
    • when converting doses >100 microgams fentanyl seek specialist advice

  • transdermal fentanyl should only be considered when patients have an opioid responsive pain and where pain control is stable:
    • as an alternative to morphine (ie a 2nd line strong opioid) but where the patient is
      • unable to tolerate morphine
      • unable to take oral medication, eg dysphagia, vomiting, coma
      • where drug compliance needs to be improved

  • specialist advice should be sought
    • when the patient has not had strong opioids
    • when the patient's pain is unstable

  • practicalities
    • patients converting from 4 hourly normal release morphine will require continued regular morphine until peak plasma levels of fentanyl are reached, ie the first 12 to 24 hours
    • patients converting from 12 hourly modified release morphine should apply the patch at the same time as taking the final 12 hourly tablet
    • patients converting from 24hourly modified release morphine should apply the patch 12 hours after taking the final 24-hourly morphine dose (2)
    • a normal release opioid preparation should always be available for breakthrough pain (equivalent to 4 hourly morphine dose)
    • the patient should be warned that they may experience more breakthrough pain in the first 1 to 3 days
    • laxatives should be reduced by up to 50% and then titrated to need
    • the dose of fentanyl patch should not be changed within the first two days of the first application or any change in dose
    • replace the patches at the same time every 3 days
    • vary the site of application with each change
    • apply to a clean, dry, undamaged, non-hairy, flat areas of skin
    • never apply heat over the patch as this will increase absorption
    • during the change over some patients (10%) experience transient symptoms of morphine withdrawal including depression, diarrhoea, sweating and sympathetic over-activity. This can usually be improved with a small dose of oral morphine
    • switching to an alternative opioid from transdermal fentanyl (2)
      • before removing an opioid patch and changing to an alternative opioid consider carefully the reasons for doing this. Carrying out this conversion correctly can be challenging and it is advisable to seek specialist palliative care advice
      • on removal of the patch, it takes approximately 17 hours for serum concentration of fentanyl to reduce by 50% and this must be considered when converting. Different methods of conversion are practised.
      • REVIEW the patient regularly during the change over period

Reference:

  • (1) West Midlands Palliative Care Physicians (2007). Palliative care - guidelines for the use of drugs in symptom control.
  • (2) West Midlands Palliative Care Physicians (2012). Palliative care - guidelines for the use of drugs in symptom control.

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