Intraoperative methadone for postoperative pain management - systematic review protocol.

Methadone is a long acting opioid initially used to treat opioid withdrawal symptoms. It has been suggested that methadone, when given as a single bolus while under anesthesia, provides good postoperative analgesia and is associated with minimal risk of opioid adverse events. Several small studies have investigated the use of methadone for postoperative analgesia with some promising results. Here we describe our protocol for a meta-analysis to investigate the postoperative analgesic effect of methadone.