Opioid antagonist treatments are medications that block the effects of opioids on the brain, aiding in recovery from opioid addiction. Naloxone is a typical opioid antagonist used in emergency overdose situations. Methadone and buprenorphine, however, are not antagonists but opioid agonists and partial agonists, respectively, used in medication-assisted treatment (MAT) to reduce cravings and withdrawal symptoms. The goal is to reduce your dose of these medications slowly over time.