Clinical experience with transdermal and orally administered opioids in palliative care patients--a retrospective study.

Background: Transdermal fentanyl is a widely used opioid for the treatment of cancer pain. Simplicity of use and high patient compliance are the main advantages of this opioid. However, based on our clinical experience, transdermal fentanyl is often not efficacious in terminally ill palliative care patients. We thus retrospectively examined the pain management and need for opioid switching in cancer patients admitted to our palliative care unit.

Methods: Of 354 patients admitted to our palliative care unit from 2004 through 2005, 81 patients were pre-treated with transdermal fentanyl. Demographic and cancer-related data (diagnosis, symptoms, pain score on a numeric rating scale (NRS)), analgesic dose at admission and discharge were compared.

Statistics: mean +/- SD, ANOVA, Wilcoxon's test was used for inter-group comparisons, significance P < 0.05, adjusted for multiple testing. Pain scores are given in median (range).

Results: Mean transdermal fentanyl dose at admission was 81.0 +/- 55.8 microg/h. In 79 patients transdermal fentanyl treatment was discontinued. In two patients, analgesic treatment according to WHO I provided sufficient pain relief. The other 77 patients were switched to other opioids: 33 patients to oral morphine and 44 to oral hydromorphone. In patients switched to morphine the dose at discharge (104.7 +/- 89.0 mg) was lower than at admission (165.5 mg morphine equivalence). In patients switched to hydromorphone the dose of 277.8 +/- 255.0 mg morphine equivalent was higher at discharge than at admission (218.2 +/- 131.4 mg morphine equivalence--considering an equianalgesic conversion ratio morphine: hydromorphone = 7.5: 1). Pain scores decreased significantly after opioid rotation (NRS at rest/on exertion: 4 (0-10)/7 (2-10) versus 1 (0-3)/2 (0-5); P < 0.001).

Conclusions: In the patient group switched to morphine, sufficient pain relief was achieved by lower equianalgesic morphine doses, compared with the doses at admission. In the patient group switched to hydromorphone, higher equianalgesic morphine doses were needed at discharge, considering an equianalgesic conversion ratio of morphine: hydromorphone = 7.5: 1. Patients with far advanced cancer often suffer from sweating and cachexia, which may have negative effects on the absorption of transdermal fentanyl. Opioid switching to oral morphine or hydromorphone was well tolerated and proved to be an efficacious option for cancer pain treatment.