While Methadone is well known for its role in medication assisted treatment for substance use disorders, its long duration of analgesia has perhaps been under-appreciated for surgical analgesia. In addition to its opioid action it has anti-hyperalgesic and anti-allodynic properties through NMDA antagonism, and Serotonin-Norepinephrine re-uptake inhibition. Doses generally given are 20mg or 0.2mg/kg. Studies indicate 24 hours or more analgesia with reduced need for supplemental analgesia.
Studies are ongoing as to its safety in different at-risk populations, e.g. coexisting medications, older, frail, cardiorespiratory disease, OSA, but this APSF article provides a great primer on Methadone in the perioperative period.