High Dose Buprenorphine (BUP) Induction in the Emergency Department (ED)

Inclusion Criteria: * Evidence of a personally signed and dated informed consent document indicating that the participant has been informed of all pertinent aspects of the study * Treated in the ED during screening hours * Meet DSM-5 diagnostic criteria for moderate to severe OUD * Clinical Opioid Withdrawal Score (COWS) score ≥ 8 * Urine toxicology positive for fentanyl * Able to speak English or Spanish sufficiently to understand study procedures Exclusion Criteria: * UDS positive for methadone. * Be pregnant determined by urine human chorionic gonadotropin (uHCG) testing * Have an unstable medical or psychiatric condition including suicidality requiring hospitalization * Require ongoing opioids for pain management * Be enrolled in formal addition treatment including by court order anytime within the last 30 days. Patients enrolled in formal addiction treatment not receiving Medications for Opioid Use Disorder (MOUD) are eligible * Be a prisoner or in custody at the time of the index visit * Have any pending legal status or pending legal action that could prohibit full participation in or compliance with study procedures. * Unable to provide one additional point of contact other than themselves * Unwilling to follow study procedures * Have prior enrollment in the current study * Have a known allergy or hypersensitivity to BUP * Have been engaged in formal addiction treatment in the 30-days prior to the ED visit (this does not include addiction treatment or residential programs where MOUD is not given (e.g. behavioral counseling, abstinence programs, NA) * Have received naloxone in the 60-minutes prior to the anticipated first transmucosal (TM) BUP administration * Is undergoing concurrent treatment with another investigational agent or enrolment in another clinical study