Opioid Use Disorder — Medication-Assisted Treatment

Opioid use disorder (OUD) is a chronic, relapsing brain disease characterized by compulsive opioid use despite negative consequences. Medication-assisted treatment (MAT), now often called medications for opioid use disorder (MOUD), is the evidence-based standard combining FDA-approved medications with psychosocial treatment, harm-reduction services, and primary medical care. Three first-line agents are buprenorphine (partial mu agonist), methadone (full mu agonist, dispensed in regulated programs), and extended-release naltrexone (mu antagonist).

Buprenorphine (sublingual films/tablets, monthly extended-release injection — sublocade, weekly/monthly brixadi) can be prescribed in office settings under federal regulation; high-dose ceiling, partial agonism, lower overdose risk than methadone, and analgesic and antidepressant properties. Methadone is dispensed daily in licensed opioid treatment programs (OTPs) with structured counseling; effective for severe OUD and pregnancy; QT monitoring required. Extended-release naltrexone monthly intramuscular requires opioid-free interval (7-10 days) before initiation; useful in highly motivated, post-incarceration, or dependence-free patients.

Outcomes of MOUD include 50-80% reduction in overdose mortality, decreased HIV and hepatitis C transmission, improved retention in treatment, reduced criminal justice involvement, and better social and occupational functioning. Pregnancy: methadone or buprenorphine recommended; naltrexone limited evidence. Co-occurring conditions (depression, PTSD, alcohol/stimulant use, hepatitis C, HIV, infective endocarditis, chronic pain) require integrated management. Harm reduction includes naloxone for overdose reversal, fentanyl test strips, syringe services, supervised consumption where available, and contingency management.