There are more than 2.1 million people in the United States with opioid use disorder, and according to preliminary data from the US Centers for Disease Control and Prevention opioid overdose deaths rose 36% to more than 69,000 deaths in 2020. Treatment with buprenorphine or methadone reduces overdose deaths in patients with opioid use disorder. However, most patients with opioid use disorder do not receive treatment. In addition to the rising rates of morbidity and mortality, the healthcare, social, and societal costs of the opioid epidemic are roughly one trillion dollars annually. Rapidly scalable strategies are needed to increase access to treatment and improve treatment retention.

The investigators propose a novel buprenorphine micro-dosing study to evaluate the pharmacokinetics, treatment retention, and qualitative outcomes in participants transitioning from methadone maintenance therapy to buprenorphine using a micro-dosing initiation in the outpatient setting. The proposed study will report participant pharmacokinetics, treatment retention, Clinical Opiate Withdrawal Scale (COWS) score, Treatment Satisfaction Questionnaire for Medication (TSQM) score, and other qualitative outcomes.

Inclusion Criteria:

• Participants will include adults (at least 18 years of age) who have been enrolled and receiving consistent treatment in the methadone program for at least 6 months.

Exclusion Criteria:

• Participants will be excluded if they are on a methadone dose > 80 mg, have concurrent alcohol use or benzodiazepine use disorder, require opioids for a pain-related diagnosis, are a current suicide or homicide risk, have a current psychotic disorder (DSM-V) or untreated major depression, have a life-threatening or unstable medical problem, or are pregnant.

Participants will include adults (at least 18 years of age) who have been enrolled and receiving consistent treatment in the methadone program for at least 6 months. Participants will be excluded if they are on a methadone dose > 80 mg, have concurrent alcohol use or benzodiazepine use disorder, require opioids for a pain-related diagnosis, are a current suicide or homicide risk, have a current psychotic disorder (DSM-V) or untreated major depression, have a life-threatening or unstable medical problem, or are pregnant.