A Randomized Controlled Trial Evaluating the Analgesic Effect of the Combination of Methadone With Morphine for Cancer Related Pain

Context and Objectives: Although opioids play an indispensable role in the management of cancer-related pain, inadequate pain relief still occurs. The primary objective of this study was to evaluate whether the combination of a low dose of methadone with morphine promotes a reduction in opioid consumption; the secondary objectives were if the association promotes lower pain intensity, and adverse effects (AEs). Materials and Methods: A sample if 41 patients with cancer-related pain in palliative setting were included. Patients were starting the third step of the analgesic ladder, and 1 group (n=21) achieve methadone (2.5 mg/12 h) in combination with morphine/methadone, and another group (n=20) received morphine alone. Both groups could use morphine (5 mg) as needed to maintain pain intensity <4, and adjuvant in stable dose. The following outcomes were evaluated: total morphine dose, pain intensity, and AEs. Results: There was no difference in the number of adjuvants, and the dose of morphine used. Pain intensity was significantly lower in the morphine/methadone group after 2 weeks, with no statistically significant difference at other timepoints. There was no difference between groups in the AEs. Conclusion: Low dose of methadone in combination with morphine provided faster pain control as compared with morphine alone, and although this study was not powered to show differences in AEs, we did not notice a difference.