A case of intractable cancer pain with bone metastasis successfully treated with partial opioid rotation from oral morphine to transdermal fentanyl

概要

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Morphine is often ineffective for cancer pain caused by bone metastasis. We partially applied transdermal fentanyl to a patient with cancer pain caused by bone metastasis who had received slow-release morphine, and observed a good pain-relieving effect. The patient had complained of severe pain in his back and legs. We at first used amitriptyline, ketamine, and lidocaine in addition to an increased dosage of morphine, which did not reduce the pain nor side effects such as nausea. We then partially employed transdermal fentanyl instead of morphine, and obtained a significant improvement of the pain as well as the side effects. The patient's blood concentration of morphine, morphine-6-glutamate (M6G), and morphine-3-glutamate (M3G) measured after the opioid rotation was 80, 355, and 2899ng/ml, respectively, and the proportion of morphine:M6G:M3G was 1:5:32. A possibility that the high blood level of M3G countered the analgesic action of morphine and M6G was considered. It was suggested that the absence of active metabolite in fentanyl contributed to its effectiveness. It was also suggested that another contributing factor was the combination of morphine and fentanyl that affected μ receptors of different subclasses. Opioid rotation from morphine to fentanyl is considered an acceptable treatment for cancer pain for which morphine is not effective.
一般社団法人日本ペインクリニック学会の論文