A Retrospective Study on the Effectiveness of Switching to Oral Methadone for Relieving Severe Cancer-Related Neuropathic Pain and Limiting Adjuvant Analgesic Use in Japan.

Background: Cancer-related neuropathic pain is resistant to treatment with multiple medications and results in reduced patient quality of life.

Objective: The aim was to find a new curative to treat neuropathic pain without using adjuvant analgesics.

Design: This was a retrospective study that used the FACES Pain Scale (FPS) to measure pain intensity and pain relief.

Setting/subjects: Twenty-eight inpatients who were treated with other strong opioids and who consulted the palliative care team about their pain relief.

Results: In 22 (78.6%) out of 28 patients who successfully switched to methadone from other strong opioids, such as oxycodone and fentanyl, within two weeks, the mean FPS score was significantly reduced from 4.43 to 1.86, and methadone switching either reduced the number of prescriptions or stopped them entirely in 12 out of 17 (70.5%) patients who had used adjuvant analgesics before switching to methadone.

Conclusions: These results suggest that opioid switching to oral methadone not only achieves pain relief but also curtails substantial adjuvant analgesic use.