<prompt> The drug which is used for long-term maintenance in opioid addictionNaloxoneNalorphineButarphanolMethadone  <response>: Maintenance Therapy After the detoxification phase is over, the patient is maintained on one of the following regimens: 1. Methadone maintenance Agonist substitution therapy 2. Opioid antagonists Opioid antagonists have been in use for a long time but they were either paial antagonists such as nalorphine or had to be administered parenterally such as naloxone Ref: A Sho Textbook of Psychiatry, Niraj Ahuja, 7th Edition, pg. no. 44 