The proposed study is a 12-week, open-label pilot study of sublocade (extended-release burprenorphine, BXR) as treatment for opiate use disorder (OUD) testing positive for Highly Potent Synthetic Opioids (HPSO). The investigators plan to enroll 10 participants into the study.

This is an open-label, uncontrolled pilot study. Outpatients seeking treatment for Opiate Use Disorder (OUD) will be screened, and those eligible who are positive for fentanyl analogues at screening will be consented and inducted onto sublingual buprenorphine (target dose 16mg to 24mg). On the fourth day after starting the buprenorphine induction, participants will receive sublocade (BXR) 300mg by subcutaneious injection. Participants will be seen twice per week for urine collection for toxicology and research assessments and will have Medication Management counseling weekly during one of these visits. BXR will be administered monthly and dosing will be according to the FDA prescribing instructions of 300mg for the second dose and 100mg for the third.

Inclusion Criteria:

• Individuals between the ages of 18-65
• Voluntarily seeking treatment for opioid use
• Meets current DSM-5 (Diagnostic and Statistical Manual) criteria for Opioid Use Disorder (OUD) as a primary diagnosis, with at least moderate severity
• Test positive for Highly Potent Synthetic Opioids (HPSO) use
• Able to provide informed consent and comply with study procedures

Exclusion Criteria:

• Meets DSM-5 criteria for substance use disorder other than opioid as the primary diagnosis
• Having a comorbid psychiatric diagnosis that might interfere with participation or make participation hazardous, such as an active psychotic disorder or current suicide risk
• Methadone maintenance treatment
• Buprenorphine maintenance treatment
• Known history of allergy, intolerance, or hypersensitivity to candidate medication (buprenorphine)
• Pregnancy, lactation, or failure to use adequate contraceptive methods in female patients, male participants are required to use adequate forms of birth control as the exposure to Sublocade on sperm and subsequent fetal development are not known.
• Unstable medical conditions, which might make participation hazardous such as uncontrolled hypertension (blood pressure >150/100), acute hepatitis, uncontrolled diabetes, or elevated liver function tests (AST (aspartate transaminase) and ALT (alanine aminotransferase) >3 times the upper limit of normal
• Legally mandated to substance use disorder treatment
• Current physiological dependence on alcohol or sedative-hypnotics that would require a medically supervised detoxification-other substance use diagnoses are not exclusionary
• Individuals, who in the clinicians judgment, have a history of failed trial of buprenorphine or sublocade (e.g. history of severe opioid intoxication or overdoses despite adequate adherence to buprenorphine or sublocade), or other features of the history that strongly suggest the patient is not a good candidate for outpatient treatment with buprenorphine.

Individual participant data that underlie the results published in this report (after de-identification) (text, tables, figures)

beginning 3 months and ending 5 years after article publication

to researcher who provides a methodologically sound proposal to achieve aims in the approved proposal

10 participants who initiated the induction process

12 weeks of study