BACKGROUNDPatients with cancer often are rotated from other opioids to methadone to improve the balance between analgesia and side effects. To the authors' knowledge, no clear guidelines currently exist for the safe and effective rotation from transdermal fentanyl to methadone.METHODSThe authors evaluated a protocol for switching opioid from transdermal fentanyl to oral methadone in 17 patients with cancer. Reasons for switching were uncontrolled pain (41.1% of patients) and neurotoxic side effects (58.9% of patients). Methadone was initiated 8–24 hours after fentanyl withdrawal, depending on the patient's previous opioid doses (from < 100 μg per hour to > 300 μg per hour). The starting methadone dose was calculated according to a 2‐step conversion between transdermal fentanyl:oral morphine (1:100 ratio) and oral morphine:oral methadone (5:1 ratio or 10:1 ratio). The correlation between previous fentanyl dose and the final methadone dose or the fentanyl:methadone dose ratio was assessed by means of Pearson and Spearman correlation coefficients (r), respectively. A Friedman test was used to compare pain intensity before and after the switch and the use of daily rescue doses.RESULTSOpioid rotation was fully or partially effective in 80% and 20%, respectively, of patients with somatic pain. Neuropathic pain was not affected by opioid switching. Delirium and myoclonus were reverted in 80% and 100% of patients, respectively, after opioid switching. A positive linear correlation was obtained between the fentanyl and methadone doses (Pearson r, 0.851). Previous fentanyl doses were not correlated with the final fentanyl:methadone dose ratios (Spearman r, − 0.327).CONCLUSIONSThe protocol studied provided a safe approach for switching from transdermal fentanyl to oral methadone, improving the balance between analgesia and side effects in patients with cancer. Cancer 2004. © 2004 American Cancer Society.

These data support the use of the RASS in Spanish patients with advanced cancer.

Our quality-of-care strategy was shown to obtain a higher level of compliance with the palliative sedation guideline for at least two years.

The dose ratio that is effective when switching opioid therapy from morphine to methadone in cancer patients varies widely. There are no conclusive data explaining the source of this variability. We analyzed 54 cancer patients undergoing opioid rotation to clarify those factors that influenced the morphine/methadone dose ratio (MMEDR) at Day 10 after the switch. Reasons for switching were uncontrolled pain (10 patients) or side effects (with or without pain, 44 patients). Initial MMEDR was 5:1 or 10:1 (82% or 18% of patients, respectively). Multivariate regression analysis was used to identify the demographic, cancer-related, and treatment-related variables that were potential predictors of MMEDR. Median previous morphine dose for the entire sample was 220 mg/day (range: 30-1000 mg/day). The stable MMEDR median was 5:1 (range: 2:1-15:1). In the univariate analysis, reasons for opioid rotation, age, and previous morphine doses were associated with MMEDR. Multiple linear regression analysis showed that only the reason for switching (pain vs. side effects; P<0.001) and previous morphine doses (lower vs. upper to 300 mg/day; P<0.001) were associated with MMEDR. From this analysis, the MMEDRs for patients rotated for side effects at 300 mg/day or more or less than 300 mg/day of morphine were 9.1:1 or 5.6:1, respectively, and the MMEDRs for those switched for pain at 300 mg/day or more or less than 300 mg/day of morphine were 4.9:1 or 3:1, respectively. Both the reasons for opioid rotation and previous morphine doses are predictive factors and should be used to select the MMEDR more accurately.

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