Methadone

Methadone (Dolophine, Amidone, Methadose, Physeptone, Heptadon and many others) is a synthetic opioid, methadoneis used medically as an analgesic, antitussive and a maintenance anti-addictive for use in patients on opioids. It was developed in Nazi Germany in 1937. Although chemically unlike morphine or heroin, methadone also acts on the opioid receptors and thus produces many of the same effects. Methadone is also used in managing chronic pain due to its long duration of action and very low cost.

Methadone's usefulness in treatment of opioid dependence is the result of several factors. It has cross-tolerance with other opioids including heroin and morphine, long duration of effects with the result that oral dosing with methadone will stabilise the condition of the patient by stopping and preventing the opioid withdrawal syndrome, and by at least partially blocking the "rush" resulting from intravenous injection of heroin, morphine, and similar drugs.

Today a number of pharmaceutical companies produce and distribute methadone, with only the racemic hydrochloride being available in the United States as of March 2008 but the tartrate and other salts of the laevorotary form (levomethadone, with trade names like Polamidone, Heptadon etc.), which is more potent and lacks the cardiac effects like lengthened QT interval caused by the dextrorotary form, being available in Europe and elsewhere. The major producer remains Mallinckrodt. Mallinckrodt sells bulk methadone to most of the producers of generic preparations and also distributes its own brand name product in the form of tablets, dispersible tablets and oral concentrate under the name Methadose in the United States.

Adverse effects

Adverse effects of methadone include: hypoventilation, decreased bowel motility - constipation, miotic pupils, nausea, hypotension, hallucination, headache, vomiting,
cardiac arrhythmia, anorexia (symptom), weight gain, stomach pain, xerostomia, perspiration, flushing, itching, difficulty urinating, swelling of the hands arms feet and legs, mood changes, blurred vision, insomnia, impotence, skin rash, seizures, death, mortality

According to the National Center for Health Statistics, as well as a 2006 series in the Charleston (WV) Gazette, medical examiners listed methadone as contributing to 3,849 deaths in 2004, up from 790 in 1999. Approximately 82% of those deaths were listed as accidental- and most deaths involved combinations of methadone with other drugs (especially benzodiazepines).

Tolerance and dependence

As with other opioid medications, tolerance and dependence usually develop with repeated doses. Tolerance to the different physiological effects of methadone varies. Tolerance to analgesia usually occurs during the first few weeks of use; whereas with respiratory depression, sedation, and nausea it is seen within approximately 5-7 days. There is no tolerance formed to constipation produced by methadone or other opioids; however, effects may be less severe after time and can often be alleviated through increase intake of dietary fiber (fruits and vegetables, high-fiber cereals, etc.) or fiber supplements.

Withdrawal symptoms of methadone include

Physiological Effects: increased lacrimation, rhinorrhea, sneezing, nausea, vomiting, diarrhea, fever, chills, tremor, tachycardia, aches and pains, often in the joints
elevated pain sensitivity, elevated blood pressure

Cognitive Effects: suicidal ideation, depression, adrenal exhaustion, adrenal fatigue, spontaneous orgasm, prolonged insomnia leading up to delirium, auditory hallucinations, visual hallucinations, enhance olfactory sense, decreased sexual drive, agitation, panic disorder, anxiety, paranoia,
delusion

Withdrawal symptoms are generally slightly less severe than those of morphine or heroin at equivalent doses but are significantly more prolonged; methadone withdrawal symptoms can last for several weeks or more. Indeed, there is a trend in the management of opiate addiction towards the reduction of a patient's methadone dosage to a point where they can be switched to buprenorphine or another opiate with an easier withdrawal profile. Ultimately, methadone is all but ideal for maintenance, but is not considered to be a desirable opiate to withdraw from when attempting to become completely opiate-free.

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