RecruitingPhase 4Drug trialOffice-based Methadone Versus Buprenorphine to Address Retention in Medication for Opioid Use Disorder Treatment.The purpose of this clinical trial is to compare the effectiveness of office-based methadone with pharmacy administration and/or dispensing to office-based buprenorphine for the treatment of opioid use disorder. This study will also examine factors influencing the implementation of office-based methadone.