A Pragmatic Randomized Control Trial Comparing Models of Care in the Management of Prescription Opioid Misuse

Inclusion Criteria: 1. Be aged between 18 and 64 years of age inclusively; 2. Prescription opioid use disorder (as defined by the Diagnostic and Statistical Manual of Mental Disorders-5 criteria), which requires opioid agonist therapy as per the discretion of the physician; 3. Female participants may be eligible if: 1. Is of non-childbearing potential, defined as (i) post-menopausal (12 months of spontaneous amenorrhea and ≥45 years of age); or (ii) documented surgically sterilized (i.e., tubal ligation, hysterectomy, or bilateral oophorectomy). 2. Is of childbearing potential, has a negative pregnancy test at screening and and agrees to use an acceptable method of birth control throughout study; 4. Be willing to be randomized to 24 weeks of either methadone or buprenorphine/naloxone adapted model of care, and to be followed for the duration of the trial; 5. Be able to provide written informed consent; 6. Be willing to comply with study procedures; 7. Be able to communicate in English or French. Exclusion Criteria: 1. Any disabling medical condition as assessed by medical history, physical exam, vital signs and/or laboratory assessments that, in the opinion of the study physician, precludes the safe participation in the study or the ability to provide fully informed consent; 2. Any disabling, unstable or acute mental condition that in the opinion of the study physician precludes safe participation in the study or ability to provide fully informed consent; 3. Heroin reported as the most frequently used opioid in the past 30 days; 4. Taken methadone or buprenorphine/naloxone for Opioid Use Disorder maintenance treatment in the four weeks prior to screening; 5. Pain of sufficient severity as to require ongoing pain management with opioids; 6. History of a severe adverse event, hypersensitivity reaction, or allergic reaction to either methadone or buprenorphine/naloxone; 7. Pregnant, nursing, or planning to become pregnant during the study period; 8. Currently taking or have taken an investigational drug in another study in the last 30 days, confirmed via self-report; 9. Pending legal action or other reasons in the opinion of the study physician that might prevent completion of the study; 10. Presence of a substance use disorder that, in the opinion of the study physician, precludes safe participation in the study (e.g. unstable or severe alcohol use disorder, unstable or severe benzodiazepine use disorder); 11. Current treatment with medications that may interact with either methadone or buprenorphine/naloxone (e.g. Clonazepam, Benzodiazepines) OR anticipation that the patient may need to initiate such treatment during the trial that is deemed unsafe by the study physician or could prevent study completion;