Which of the following patient characteristics would most strongly suggest that agonist (methadone or buprenorphine) treatment, rather than antagonist (naltrexone), is more likely to be appropriate for medication-assisted treatment (MAT) of opioid use disorder? 1) high motivation for abstinence 2) high need for external structure 3) history of opioid use via non-IV routes only 4) one-year history of opioid use disorder 5) relapse during prior agonist treatment
