Evaluating Buprenorphine/Naloxone Microdosing vs. Standard Dosing in Emergency Departments

Inclusion Criteria: We will include ED patients ≥18 years of age with opioid use disorder who are being discharged from the ED. We will define opioid use disorder as non-medical opioid use in the previous 30 days and a positive score for opioid dependency based on the validated Rapid Opioid Dependence Screen (RODS). All patients will also be assessed by the treating physician or degree of clinical opioid withdrawal, based on the clinical opiate withdrawal scale (COWS) score. Patients will be eligible for the take-home study interventions if they have a COWS score \<=12, as a score greater than 12 would mean the patient is a candidate for standard buprenorphine induction in the ED at that moment in time, and would therefore not be eligible for outpatient study interventions. Exclusion Criteria: * Active withdrawal at time of ED assessment (Clinical Opiate Withdrawal Score \[COWS\] \>12) * Admitted to hospital * Severe communication barriers that inhibit patients' understanding of study procedures and interventions * Are taking opioids for cancer or palliative-care related indications * Are deemed unsafe to approach by ED providers * Incarceration * Not a resident of the province in which they are seeking care (BC or Alberta) * Actively receiving OAT, defined as having filled a prescription for one of the following medications in the 5 days prior to ED presentation: buprenorphine/naloxone, methadone, sustained release morphine, injectable hydromorphone, injectable diacetylmorphine * Prior enrollment in the study * Known or suspected mechanical gastrointestinal obstruction (e.g., bowel obstruction or strictures) or any diseases/conditions that affect bowel transit (e.g., ileus of any type). * Suspected surgical abdomen (e.g., acute appendicitis or pancreatitis). * Severe respiratory insufficiency. * Severe CNS depression, increased cerebrospinal or intracranial pressure, and head injury. * Complicating patient factors that make home inductions from the ED unsafe and/or that require expert consultation for consideration of induction in an observed setting. These factors include: * Allergy to buprenorphine/naloxone * Severe respiratory or liver dysfunction * Concurrent withdrawal or intoxication from sedatives (e.g., alcohol, benzodiazepines) * Active prescription for sedative medications (e.g., benzodiazepines, opioids) * Use of monoamine oxidase inhibitors within the past 14 days * Concerns that the patient is unable to safely store medications * Pregnancy (we will obtain a point-of-care urine pregnancy test on all women of child-bearing age prior to enrollment)