methadone:

Methadone (also known as Symoron, Dolophine, Amidone, Methadose, Physeptone, Heptadon and many other names) is a synthetic opioid. It is used medically as an analgesic and a maintenance anti-addictive and reductive preparation for use by patients with opioid dependency. It was developed in Germany in 1937, mainly because Germany required a reliable internal source of opiates. Because it is an acyclic analog of morphine, methadone acts on the same opioid receptors 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