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.
Methadone is useful in the treatment of opioid dependence. It has cross-tolerance with other opioids including heroin and morphine, offering very similar effects and a long duration of effect. Oral doses of methadone can stabilise patients by mitigating opioid withdrawal syndrome. Higher doses of methadone can block the euphoric effects of heroin, morphine, and similar drugs. As a result, properly dosed methadone patients can reduce or stop altogether their use of these substances.
Methadone is approved for different indications in different countries. Common is approval as an analgesic and approval for the treatment of opioid dependence. It is not intended to reduce the use of non-narcotic drugs such as methamphetamine, or alcohol.
A number of pharmaceutical companies produce and distribute methadone. The racemic hydrochloride is the only form available in most countries, such as the Netherlands, Belgium, France and in the United States, as of March 2008. The tartrate and other salts of the laevorotary form (levomethadone, with trade names including Polamidone and Heptadon) are available in Europe and elsewhere. These are more potent opioid agonists compared to racemic methadone because the dextrorotary form (d-methadone) is not an opioid agonist (it is an NMDA antagonist), therefore by using only the laevorotary form instead of the racemate the opioid agonist potency is doubled. Covidien (formerly Mallinckrodt), is the major racemic methadone producer and sells bulk methadone to producers of generic preparations and distributes its own product in the form of tablets, dispersible tablets and oral concentrate under the brand name Methadose in the United States.