Both treatments were equally protective against mortality and delivered similar effectiveness and patient adherence.
Paramedics across B.C. attended to a record-breaking 256 drug poisoning calls on January 21, 2026 — almost 10 years after the April 2016 provincial declaration of a public health emergency due to the growing number of toxic drug-related overdoses. Preventing toxic drug poisonings continues to be a multi-pronged effort, with research playing a central role in evaluating the effectiveness of a suite of services, including medications for opioid use disorder, also called opioid agonist therapy.
Vancouver Coastal Health Research Institute (VCHRI) researchers Drs. M. Eugenia Socías and Nadia Fairbairn contributed to the newly released first study providing clinical evidence on the comparative effectiveness of slow-release oral morphine (SROM) and methadone for the treatment of opioid use disorder (OUD). The study’s goal was to determine the difference in treatment outcomes between the two medications.
“SROM has been shown to be effective in other parts of the world, including Europe, but is a relatively new addition to the suite of treatments for OUD in B.C.,” states Fairbairn.
“It is important to evaluate the effectiveness of SROM in a B.C. context, as every jurisdiction has unique patient demographics, needs and circumstances, as well as different modes of health care delivery.”
Similar to other opioids, both SROM and methadone are full-opioid agonists, meaning that the higher the dose, the stronger the effect, which increases the potential risk for hypoventilation and respiratory failure. As such, both treatments are first given under the supervision of a care provider or pharmacist, with subsequent take-home options available if appropriate for the patient. However, unlike SROM, methadone has more known drug interactions and concerning side effects, such as heart arrhythmia, potentially making SROM a better option for some patients.
“In the case of SROM and methadone, we know that they work for some patients, but we do not know as much about which patients may benefit most from either SROM or methadone and why,” says Socías. “As a comparison, even for diseases with many treatment options, such as HIV, researchers continue to evaluate current treatments and explore alternatives to reduce drug interactions and side effects and to improve patient care.”
Ongoing engagement is needed to retain patients in treatment
Socías and Fairbairn’s study included the electronic medical records and linked health data from health facilities like pharmacies from 3,254 unique individuals with OUD receiving care in the Vancouver Coastal Health (VCH) region of B.C. This region also has a high prevalence of high-potency synthetic opioids — a class of drug that includes fentanyl.
Fentanyl is approximately 50 to 100 per cent more toxic than other opioids like morphine, making it a high-risk factor for overdose and potentially death. Additionally, fentanyl can be mixed with other harmful substances, such as the animal tranquilizer, medetomidine.
“B.C. has been particularly affected by the toxic drug crisis, with an opioid-related death rate of 40.6 per 100,000 population in 2024 and with fentanyl being detected in 84 per cent of these deaths.”
Opioid use disorder is a chronic disease that alters brain chemistry and leads to addiction and dependence. Not taking opioids after prolonged use can cause severe and sometimes life-threatening physical and psychological withdrawal symptoms.
“It leads to overwhelming cravings,” Socías shares. “It is very difficult to get off opioids because of the severity of the withdrawal symptoms. Depending on how long someone has been taking them, there is also a heightened risk of overdosing for a person who has lowered or stopped their opioid use and then takes a higher dose.”
“Similar to diabetes, opioid use is a chronic relapsing condition that may require taking medication on an ongoing basis to not only prevent death, but to live a better life.”
Medications for OUD, like SROM and methadone, work only when taken regularly and as prescribed. However, treatment discontinuation is particularly high among individuals with OUD.
Of the 4,059 charts of people with OUD — some from the same individuals — that the study team reviewed, 2,737 were for methadone prescriptions and 1,322 were for SROM prescriptions. Results of the 12-month study showed that treatment discontinuation was slightly lower among the methadone group (97.9 per cent) as compared with the SROM group (99.3 per cent), with a median treatment duration of eight days in the methadone group and three days in the SROM group.
“Both treatments were found to have similar clinical effectiveness and mortality risk,” says Socías. “Sadly, though, 121 people included in this study died within one year.”
“However, only two deaths occurred when people were taking medication for OUD, reinforcing the importance of continuous engagement in these treatments to reduce the risk of dying.”
Socías is conducting a follow-up analysis on patient characteristics and costs of SROM and methadone in hopes of better understanding which patients would most benefit from either treatment given patient characteristics and other factors.
