Opioid Rotation to Methadone for Refractory Cancer Pain: A Case Series.

Methadone has been increasingly used in the treatment of refractory cancer pain with different conversion methods and ratios described.A retrospective chart review of patients on methadone for cancer pain was conducted to assess its use as the primary opioid, focusing on pain characteristics, opioid rotation indication, previous analgesics, adverse effects and final methadone dose in comparison with the pre-rotation Morphine Equivalent Daily Dose (MEDD).Eight patients were rotated to methadone due to refractory moderate-severe cancer pain and achieved good pain relief. Three developed adverse effects (2 mild, 1 serious). None required withdrawal of methadone. The final methadone dose required varied significantly from predictions made based on equianalgesic conversion tables.Methadone is effective for the treatment of refractory cancer pain. The eventual required methadone doses for these patients were significantly different from predicted doses suggested by equianalgesic conversion tables and guidelines. This highlights the importance of individualized titration and careful clinical assessment during the rotation and in the days after, to prevent serious adverse effects.