An opioid partial agonist. This means that, although buprenorphine is an opioid, and thus can produce typical opioid agonist effects and side effects such as euphoria and respiratory depression, its maximal effects are less than those of full agonists like heroin and methadone. Used to treat opioid (narcotic) dependence or addiction, and to treat moderate to severe pain. It can be taken intravenously, orally or transdermally.