[This section is adapted from GAO, 2009.]

Methadone has been used for the treatment of opioid addiction and pain, and it is relatively inexpensive compared to other opioids. Because methadone has a much longer half life than most opiates (up to 30 hr), initial dosing and modification of the dosing regimen are much different than for the faster-acting opiates because the drug takes longer to clear. This is the desired property that led to methadone as the choice for recovering opiate addicts.

A once-a-day dose will activate the MOR receptors and alleviate withdrawal symptoms, while at the same time occupying those sites so that a new dose of opiate will have little effect and not give the “rush” the addict may have desired. Most of the earlier use for methadone has been in opioid treatment programs to help recovering heroin or other prescription opiate addicts (CDC, 2002).

Since the late 1990s, methadone has been increasingly prescribed by practitioners to treat patient pain. However, while a single dose suppresses opioid withdrawal symptoms for a day or more, it generally relieves pain for only 4 to 8 hours while remaining in the body much longer. Further, it may take several days to achieve full pain relief, so dosage increases must be done more slowly than with other opioids. Patients may feel the need to take more methadone before the previous dose has cleared, leading to potential overdose, with depressed respiration.

Liquid methadone is most commonly used for addiction treatment, while the 5- and 10-mg tablets are most often prescribed for pain management. The FDA considers methadone safe and effective for both pain management and addiction treatment, although not all forms of methadone are FDA-approved for both of these purposes.

In 2001 healthcare providers and hospitals were required to guarantee that their patients received appropriate pain treatment when the Joint Commission, a national healthcare facility standards-setting and accrediting body, implemented pain standards for hospital accreditation. Methadone was initially used more for the treatment of cancer pain, but it has been increasingly used for chronic noncancer pain.

The growing availability of methadone through its increased use for pain management is a contributing factor to the rise in methadone-associated overdose deaths. Drug Enforcement Administration (DEA) data show that from 2002 to 2007 distribution of methadone to businesses associated with pain management—pharmacies and practitioners—almost tripled. Similarly, data from IMS Health showed that from 1998 through 2006 the number of annual prescriptions of methadone for pain increased by about 700 percent, from about 531,000 in 1998 to about 4.1 million in 2006.

Lack of knowledge about the unique pharmacological properties of methadone by both practitioners and patients has also been identified as a factor contributing to methadone-associated overdose deaths, especially when initiating a treatment with methadone or converting patients to methadone from other opioids.