Purpose：Methadone is an opioid used in Japan for the treatment of cancer pain. A thorough consideration of complex pharmacokinetics with individual differences and of serious adverse effects is necessary before switching to methadone; therefore, methadone is not yet widely used. We examined the analgesic and adverse effects of methadone through clinical cases and considered the clinical significance of methadone as an opioid analgesic for the treatment of cancer pain. Methods：The clinical course of 44 patients with cancer pain who were switched to methadone from other opioids was analyzed. Results：Out of the 44 cases investigated, 37 cases （84.1％） were successful. In the successful cases, pain intensity before and after methadone administration was reduced from an average of 7.5 to 2.8, respectively, on the numerical rating scale. Strong drowsiness （six cases） and nausea （three cases） were observed as adverse effects. However, no serious effects, such as QT prolongation and respiratory depression, were recognized. Conclusion：For patients with refractory cancer pain who require a high opioid dose, methadone is considered to be one of the alternatives in pain therapeutics.

Background: Methadone can only be administered orally in Japan. However, it is unclear how to treat pain when patients become unable to take methadone orally because of the progression of the disease. Aims: To assess retrospectively end-of-life pain control management after patients become unable to take methadone orally. Methods: Twenty-eight patients with cancer pain undergoing treatment with oral methadone died at a palliative care unit between April 2013 and September 2014. All patients died of cancer and were unable to swallow before death. We assessed pain control approaches after the patients became unable to take methadone orally. Results: Twenty-one patients survived 1 day or longer after becoming unable to swallow. Methadone was switched to another opioid because of pain. Of these 21 patients, 10 patients survived for 1 week or longer after being switched to another opioid. At this point, methadone would be mostly eliminated from the blood circulation. Among these 10 patients, seven patients were treated with subcutaneous morphine, and three patients were excluded because their pain could not be evaluated. The conversion ratio from final oral methadone dosage to oral morphine equivalent dose of opioids used on the seventh day was 6.1. Conclusion: Even when patients become unable to ingest methadone, switching to other opioids may not always be necessary because of the long half-life of methadone when pain is absent at the end of life. If necessary, pain could be managed by switching to other opioids with a conversion ratio of 6.1.

Introduction: This is the first report about an outpatient who was successfully switched from oxycodone to methadone without any serious problems in Japan. Case report: A man in his 60s who was diagnosed as advanced pancreatic cancer with multiple bone and liver metastases. Since he complained severe cancer pain in spite of taking oxycodone 40mg/day, he was referred to the palliative care team. After discussion about switching from oxycodone to methadone in the palliative care team and obtaining informed consent from him, it was decided to prescribe methadone in the outpatient setting. During induction of methadone, a palliative care certified nurse (CN) played important roles about explanation of futures, pharmacodynamics, pharmacokinetics and side effects, education how to take, monitoring of analgesic and side effects and supports to patient anxieties about methadone. His dose titration of methadone was completed for 15 days, and his adequate dose was decided as 20 mg/day finally. After titration of methadone, pain relief could be achieved. Conclusion: Although methadone has a possibility to improve management of cancer pain, it has some serious problems, such as respiratory depression, QT interval prolongation and others due to unsuitable use. Therefore, patients with prescription of methadone must be educated, monitored and supported by special medical staff with much experiences and knowledge about cancer pain, opioid therapy and methadone. CNs may play important role to keep safety and resolve patients and families’ anxieties for prescription of methadone.