The overall objective of this study is to explore the feasibility of transitioning the care of adult patients with opioid use disorder (OUD) who receive office-based buprenorphine treatment (OBBT) from physicians to pharmacists. Physicians will induce buprenorphine treatment and complete the stabilization phase before referring patients to pharmacists for the management of monthly maintenance visits. This study will assess the feasibility and acceptability of a collaborative care model between physician and pharmacist by measuring recruitment rate, treatment retention rate, treatment compliance rate, and participants' substance use. Other assessments measured will include treatment fidelity, participant, physician, and pharmacist satisfaction with OUD care, participant safety, and the pharmacists' use of electronic health records and the Prescription Drug Monitoring Program.