The experimental intervention is a high daily maintenance dose of buprenorphine (24 mg) plus any usual clinical care the participant receives at the clinic. This high daily dose is the upper limit of the FDA-approved dose range and was selected based on preclinical studies, clinician anecdotes, case reports, and retrospective analyses suggesting improved effectiveness of higher buprenorphine doses among patients with a history of fentanyl use. Underlying pharmacodynamic principles support that the 24 mg daily dose of buprenorphine is likely to be well-tolerated, safe, and better control cravings among people with a history of fentanyl use.

The control intervention is the FDA-recommended target daily maintenance dose of buprenorphine (16 mg) plus any usual clinical care the participant receives at the clinic.

Buprenorphine in a highly effective treatment for opioid use disorder (OUD). Buprenorphine dose guidelines for OUD treatment were determined by clinical trials conducted in populations with a history of heroin use. However, fentanyl is changing the calculation of treatment, and optimal buprenorphine dosing for people who use fentanyl is unknown.

The primary outcome is the percentage of participants retained in buprenorphine treatment. Participants will be classified as retained in buprenorphine treatment at six months post- randomization if (1) the study site data indicate that they remained engaged in treatment or (2) the PDMP suggest that they continued treatment elsewhere and have not had a gap of more than 27 days in medication on-hand based on fill dates and days' supply.

Measured using patient reported outcomes via the Opioid Craving Scale, a reliable, validated scale for people with opioid use disorder. The scale consists of three questions related to opioid cravings rated on a scale of 1-10 with 1 being not at all and 10 being extremely. A higher score denotes increased opioid cravings.

Non-fatal and fatal opioid overdoses will be assessed using statewide data from the Rhode Island Department of Health, including the Emergency Medical Services (EMS) Information System, Opioid Overdose Reporting System (OORS), and Office of the State Medical Examiners (OSME). All of these systems report non-fatal or fatal opioid overdoses which investigators will aggregate to arrive at the rate of non-fatal or fatal opioid overdoses.