Methadone, also known as Dolophine among other brand names, is a synthetic opioid. It is used medically as a pain medication and a maintenance therapy in people with opioid dependence. Methadone is also used in managing severe chronic pain owing to its long duration of action and strong analgesic effect.Side effects are similar to that of other opioids. The number of drug-poisoning deaths in the United States involving methadone increased from 784 in 1999 to 5,518 in 2007 but declined to 4,418 in 2011.Methadone is an acyclic analog of morphine and heroin and acts on the same opioid receptors.Methadone was developed in Germany in 1937 by Gustav Ehrhart and Max Bockmühl, mainly because Germany required a reliable internal source of opioids. Methadone was introduced into the United States in 1947 by Eli Lilly and Company. It is regulated similarly to morphine in most countries. In the United States, it is a Schedule II controlled substance. Globally in 2013 41,400 kilograms were manufactured. Methadone is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system.