To add to the choice of opioid analgesics used in palliative care we now have in Australia fentanyl patches. Each patch is worn for 72 hours and has about the same effect as using twice daily oral sustained release(SR) morphine. However from a quality of life point of view there are some advantages in using fentanyl patches for some patients. It is not yet listed on the Pharmaceutical Benefits Scheme and is quite expensive. So what is its present role in palliative care and how is it used?
The main side effects complained of by patients on morphine are nausea, vomiting, constipation and drowsiness all of which can significantly impact on quality of life even though pain relief may be adequate. For total pain management both physical and psychological factors need to be taken into account. According to a study comparing transdermal fentanyl versus sustained release oral morphine the following has been found.20(1)
Pain control
No significant difference was found between fentanyl and SR morphine in regards to pain control. However those on fentanyl did require slightly more breakthrough doses of morphine.
Sedation and sleep
Fentanyl appeared to be less sedating than morphine both in the daytime and night.
Bowel function
Fentanyl treatment was associated with significantly less constipation than morphine.
Nausea
This was significantly lower in the fentanyl group.
Treatment preferences
Significantly more patients indicated that the fentanyl patches had caused less interruption to their daily activities and the activities of family and carers, and had been more convenient to take than morphine tablets.
Withdrawl from morphine symptoms were common and symptoms such as abdominal pain, agitation or anxiety, sweating and 'flu' like symptoms were reported during the first few days of fentanyl treatment consistent with morphine withdrawl.
A second line drug
It should be emphasised that fentanyl is not suitable for unstable pain or rapid titration. In those situations morphine must first be used preferably on a four hourly basis until adequate pain control is acheived. If there are then indications to use fentanyl then the change is made according to the conversion formula listed below.
24-hour morphine (mgm/day)
Fentanyl dose (mcg/hr)
<135
25
135-224
50
225-314
75
315-404
100
405-494
125
495-584
150
585-674
175
675-764
200
765-854
225
855-944
250
945-1034
275
1035-1124
300
There are four sizes of patch and more than one patch can be used if a higher dose is needed.The four sizes of patch have a delivery rate of 25,50,75 and 100mcg per hour.
Notes
(1) Fentanyl is excreted in the urine and the dose may need to be reduced if there is increasing dehydration or renal failure.
(2) As regards cost fentanyl is approximately three times as expensive as morphine.
(3) Care must be taken to adequately dispose of used patches and it is recommended that sharps containers be used for disposal.
Summary
Fentanyl is a very good opioid analgesic that is particularly useful for those people who are intolerant of morphine. However it should be considered a second line drug after morphine and is not nearly as flexible as 4 hourly morphine. It is used particularly for those with severe morphine related constipation or nausea, those who have excessive morphine induced sedation, those with poor compliance or inability to swallow and those who have inadequate pain relief with morphine. It is easy to use and well accepted by the patient. It will hopefully soon be listed on the PBS.
(1) Reference: Transdermal Fentanyl versus Sustained-Release Oral Morphine in Cancer Pain: Preference, Efficacy and Quality of Life. Journal of Pain and Symptom Management. Vol 13, No.5, May 1997.
