Methadone as first-line opioid treatment for cancer pain in a developing country palliative care unit

The use of methadone for cancer pain is limited by the need of expertise and close titration due to variable half-life. Yet, it is a helpful palliative strategy in low-resources countries given its long-acting effect at low cost and worth additional study. Our aim was to describe the prescription and outcomes of methadone as a first-line treatment for cancer pain in a tertiary palliative care unit (PCU) in Argentina.

Retrospective review of medical records of patients with moderate to severe cancer pain seen at the PCU in 1-year period, who initiated strong opioids at the first consultation. Data collected during the first month of treatment included disease and pain characteristics, initial and final opioid type and dose and need for opioid rotation.

Methadone was the most frequent opioid both at the initial and last assessment (71 and 66 % of the prescriptions). In all, treatment with strong opioids provided considerable decrease in pain intensity (p < 0.001) with low and stable opioid dose. Median and interquartile range (IR) of oral morphine equivalent daily dose (OMEDD) was 26 (16-32) and 39 (32-55) mg for initial and final assessments, respectively (p = 0.3). In patients initiated with methadone, the median (IR) daily methadone dose was 5 (4-6) mg at first and 7.5 (6-10) mg at final assessment, and the median (IR) index of opioid escalation was 0 (0-4) mg; (p < 0.05). Patients on methadone underwent less percentage of opioid rotation (15 versus 50 %; p < 0.001) and longer time to rotation (20.6 ± 4.4 versus 9.0 ± 2.7 days; p < 0.001) than patients on other opioids.

Results indicate the preference of methadone as first-line strong opioid treatment in a PCU, providing good pain relief at low doses with low need for rotation. Several considerations about the costs of strong opioids in the region are given.