Mouse anti-Human ERBB2 monoclonal antibody for IA. Methadone (also known as Symoron, Dolophine, Amidone, Methadose, Physeptone, Heptadon, Phy and many other names) is a synthetic opioid, used medically as an analgesic and a maintenance anti-addictive for use in patients with opioid dependency. It was developed in Germany in 1937. Although chemically unlike morphine or heroin, methadone acts on the same opioid receptors as these drugs, and thus has many of the same effects. Methadone is also used in managing severe chronic pain, owing to its long duration of action, extremely powerful effects, and very low cost. Methadone was introduced into the United States in 1947 by Eli Lilly and Company.