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How to calculate the dose of S/C morphine when converting from Durogesic DTrans

Step 1	Take dose of Durogesic DTrans
	Check on conversion chart what the equivalent oral morphine dose is. This will be a range. Usually take the lower end of the range.
	Convert to S/C morphine dose by ÷2
	Round this to the nearest ampoule size
	This will be the dose of S/C morphine

Example:

Conversion to Subcutaneous morphine from 50mcg per hour Durogesic DTrans patch (as per manufacturer's guidelines)
Durogesic DTrans dose	= 50 mcg /hour Durogesic DTrans
Equivalent 24hour ORAL MORPHINE dose (range)	= 135 – 189mg
	÷ 2
Divide this by 2 to arrive at the 24 hour S/C morphine dose	= 67 - 94mg

Equivalent practical dosage morphine/24 hours	= 70mg / 24 hours

To calculate breakthrough dose:
Subcutaneous - 24 hour morphine dose ÷ 6	= 10 mg (approximately)
Oral - SC B'thro dose X 2 (e.g. 10mg x 2)	= 20 mg

Procedure

Remove the patch ( Note time of removal)
Calculate appropriate breakthrough analgesia and ensure that this is available throughout this period
12 hours after patch removal > Start the 24 hour SC infusion of morphine
Make arrangements for regular observation / pain assessment throughout this period

It is clear from the above advice that it may be best, where possible, for such changes in medication to be carried out in a well supported environment preferably as an in-patient until pain control is once again stable or if necessary at home with community or Macmillan nurse involvement.

This information relates to circumstances where the patient's prognosis is longer than that described in Greta's case study and it is not an end of life situation.