Efficacy and Safety of Methadone as a Second-Line Opioid for Cancer Pain in an Outpatient Clinic: A Prospective Open-Label Study

Abstract

Introduction. Most clinical reports on methadone rotation describe outcomes in hospitalized patients.The few studies that have included outpatients are retrospective.The aim of this study was to assess the efficacy and safety ofmethadone as a second-line opioid in adult patients with advanced cancer after rotation in routine clinical practice at a palliative care outpatient clinic. Patients and Methods. This was a prospective, open-label study of 145 patients whose treatment was rotated from other opioids to methadone. Informed consent was obtained in all cases. The main outcome measure was change in the variable “worst pain” at day 28. Pain and pain interference were assessed with the Brief Pain Inventory, with side effects evaluated according to the Common Terminology Criteria for Adverse Events version 3.0. Pain levels were evaluated at study entry and at days 3, 7, 9, 14, 21, and 28. Results. Rotation to methadone was performed for the following reasons: poor pain control (77.9%), opioid side effects (2.1%), or both (20%).Themean daily oral morphine equivalent dose before rotation was 193.7 mg.The median worst and average pain scores decreased significantly (p, .0001) from baseline to day 28: The median worst pain score decreased from 9 (interquartile range [IQR]: 8–10) to 6 (IQR: 3–8), and the median average pain score decreased from 6 (IQR: 5–7) to 4 (IQR: 2–5). The proportions of patients with moderate to severe worst and average pain decreasedby30.3%and47.5%,respectively,byday28.Noincrease in opioid toxicity was observed during the study. Conclusion. In outpatients with advanced cancer, rotation to methadone as a second-line opioid was efficacious and safe when using a tiered scheme with close follow-up by experienced health professionals.