Methadone Fact Card
What is methadone?
Methadone is a synthetic opioid, available in the United States only by prescription and for use by licensed medical facilities. Methadone is classified as a narcotic analgesic, dispensed primarily for treating opioid use disorder (OUD) during medication-assisted therapy (MAT) — available in the form of oral tablets, oral solutions, and injectable forms. As an analgesic, methadone might be prescribed for treating pain. However, methadone carries a high potential for addiction, misuse, and diversion. So, physicians are generally discouraged from prescribing methadone as a first option for treating pain;  though many view it as a valuable option for treating cancer-related pain.  Street methadone is licitly manufactured methadone that is either a diverted prescription or the subject of another form of diversion.
What is medication-assisted therapy?
Medication-assisted therapy (MAT) pertaining to the treatment of opioid use disorder (OUD) involves replacing the use of shorter acting and highly addictive opioids, such as heroin or oxycodone, with controlled and medically-supervised dosing of a longer acting, less addictive, and less euphoric opioid — typically buprenorphine or methadone.  This approach allows the opioid-addicted patient to avoid the persistent cravings and roller-coaster effects associated with short-acting opioid use, in addition to the debilitating withdrawal symptoms associated with cold-turkey abstinence. MAT allows for the patient to reach a level of stability, where patient and clinician may choose to continue with opioid maintenance treatment or pursue withdrawal management.  With any approach to treating opioid use disorder, concurrent psychosocial treatment is viewed as an essential cornerstone. 
What are the effects of methadone?
Methadone acts on the brain's opioid receptors as a full opioid agonist, making it effective at curbing cravings and withdrawal symptoms in users who have developed physical dependence on opioids. Compared with other opioids, methadone produces only minimal levels of euphoria — and when used in sufficient dosage, is also effective at impeding the euphoric effects of other opioids, such as heroin.  Due to these factors, methadone is commonly used as an opioid replacement drug during medication-assisted therapy (MAT). However, similar to the opioids it is intended to replace, methadone is prone to abuse and is highly addictive, capable of producing harsh withdrawal symptoms when abstinence is attempted by users with physical dependence on methadone or other opioids. 
Because methadone produces little euphoria or "high", it is not commonly pursued as a recreational drug. Other opioids, such as heroin, oxycodone, hydrocodone, morphine, or codeine, are typically pursued for these purposes. The majority of illicit methadone use involves individuals with physical dependence on opioids, using the drug in order to avoid the harsh withdrawal symptoms associated with cold-turkey abstinence. 
Methadone has a very long duration of action and a long and unpredictable half-life.  Additionally, methadone can accumulate in the liver, then slowly release into the bloodstream over time.  These factors lead to a great deal of uncertainty with dosing and a high risk for respiratory depression and overdose, especially in new, opioid naive users and those taking benzodiazepines, such as Xanax. In 2009, methadone was involved in 30% of opioid overdose deaths, while accounting for only 2% of opioid prescriptions. 
Methadone Diversion and Abuse
As a narcotic analgesic with a high potential for abuse and diversion, methadone is the subject of very tight governmental controls and monitoring. Under US federal law, methadone patients for opioid use disorder (OUD) cannot be provided with monthly or weekly take-home prescriptions. Instead, certified opioid treatment programs (OTPs) must provide daily supervised dosing of methadone to their patients. OUD patients are allowed take-home methadone doses only under very limited circumstances.  These restraints do not apply to methadone prescribed for treating pain. Consequently, diverted pain prescriptions are a major source of illicit street methadone. The majority of methadone overdose cases are believed to involve illicit methadone obtained through diverted pain prescriptions. Accordingly, the FDA and DEA have made efforts to reduce pain prescriptions for methadone, with some success. 
Urine Testing for Methadone
According to "Disposition of Toxic Drugs and Chemicals in Man" (3rd ed): approximately 5–50% of a methadone dose is recovered in the urine as unchanged methadone, 2–25% as EDDP, and less than 1% as EMDP. These rates are significantly impacted by variations in urine pH, urine volume, dose, and rate of metabolism. In methadone maintenance subjects, urinary concentrations of methadone and EDDP ranging from 1,000–50,000 ng/mL are commonly encountered.