Switching from oxycodone to methadone in advanced cancer patients

The aim of this study was to prospectively evaluate the outcomes and the conversion ratio of switching from oxycodone to methadone in advanced cancer patients admitted to an acute palliative care unit. A prospective study was carried out on a cohort of consecutive sample of patients receiving oxycodone, who were switched for different reasons mainly because of an inconvenient balance between analgesia and adverse effects. An initial conversion ratio between oxycodone and methadone was 3.3:1. Intensity of pain and symptoms associated with opioid therapy were recorded, and a distress score (DS) was also calculated as a sum of symptom intensity. A successful switching was considered when the intensity of pain and/or DS or the principal symptom requiring switching decreased at least of 33% of the value recorded before switching. Nineteen out of 542 patients admitted to the unit in 1 year underwent a switching from oxycodone to methadone. Almost all substitutions were successful. The prevalent indication for opioid switching was uncontrolled pain and adverse effects (12 patients). No significant changes between the initial conversion ratio and final conversion ratio between the two opioids were found. Switching from oxycodone to methadone is a reliable method to improve the opioid response in advanced cancer patients. A ratio of 3.3 appears to be reliable, even at high doses. Further studies should be performed to confirm these results in other settings and with very high doses of oxycodone.