The usual treatment for opioid use disorder (OUD) is opioid agonist therapy (OAT) with either methadone or buprenorphine. These treatments are well-established, reduce the risk of fatal overdoses, and are considered the standard approach. However, current methadone guidelines were developed when most people were using heroin, which is far less potent than today's unregulated/illicit fentanyl supply. As a result, people who use fentanyl often need higher doses to feel stable. Because methadone must be started at low doses and increased slowly, it can take weeks before someone reaches an effective dose. This process becomes even longer when doses are missed, since treatment often needs to be restarted at a lower level.
The Methadone Rapid Restart is a newer strategy designed to take ongoing fentanyl use into account. Early clinical experience and modelling suggest that many people who use fentanyl have high opioid tolerance and may be able to return to their previous stable methadone dose even after several missed days, without added safety risk. This approach has shown promise in small clinical settings, but it is not yet known whether it provides better outcomes than the standard methadone titration used today. This study will be testing whether this protocol to help rapidly restart people on Methadone is acceptable for patients and use the learning to guide a subsequent larger clinical trial.