Opioid switch in palliative care, opioid choice by clinical need and opioid availability.

Availability of different WHO-step 3 opioids has encouraged the discussion on their value and led to the concepts of opioid rotation. Rotation is suggested, when other measures fail to achieve optimal analgesia and tolerability in cancer pain treatment. Opioid use was assessed in a prospective cohort study of 412 palliative care patients from 14 inpatient and outpatient palliative care facilities in Germany. The most frequently used opioids at baseline were morphine and fentanyl. The most frequent changes in medication (N=106) occurred from oral to parenteral morphine. Only in 49 cases true switches to other long acting opioids were recorded. This is far less than expected from other reports. True switches and adverse side effects were found to occur more frequently in inpatients, while efficacy problems were more frequently recorded in outpatients. There was no correlation between the opioid used at baseline and switch frequency, but numbers of cases receiving other opioids than fentanyl or morphine were low. Reasons for and frequencies of changes in medication were found to be largely shaped by the setting reflecting patients' needs and clinical necessities. Recommendation of first line therapy and availability of opioid formulations define the frequency of opioid use. This impedes evaluation of specific differences between the opioids.