Methadone was involved in more than 30% of opioid-related deaths in the United States in 2009, second only to the painkiller oxycodone, according to new data from the Centers for Disease Control and Prevention.
The high rate of overdose deaths from methadone occurred even though the drug accounted for less than 2% of opioid prescriptions in 2009. Part of problem is that methadone is more likely than other opioids to cause an overdose, according to the CDC. For example, a toxic level of methadone can accumulate in the body, leading to severe respiratory depression. Methadone can also cause major disturbances in cardiac rhythm.
"It acts differently in different people’s bodies," Dr. Thomas R. Frieden, director of the CDC, said during a press conference to announce the new data. "So it’s possible that someone can take just a small amount, but it may last for days in their system and cause serious health problems."
Dr. Frieden noted that the increase in overdose deaths from methadone is primarily due to increased use of the drug in pain treatment, not as part of addiction treatment programs.
The findings, which were published on July 3 in Morbidity and Mortality Weekly Report, show that as the use of methadone for pain relief has risen, so has the number of overdose deaths associated with the drug (MMWR 2012;61:1-5).
The annual rate of methadone prescriptions for pain rose to 1.5 per 100 persons in 2008 and held steady in 2009. At the same time, the mortality for the drug reached 1.8 deaths per 100,000 persons in 2007 and then dropped slightly in the next 2 years. Between 1999 and 2009, the number of overdose deaths involving methadone increased 5.5 times. Methadone was involved in 31.4% of the 3,294 opioid deaths in the United States in 2009.
The findings are based on national data from the CDC, the Food and Drug Administration (FDA), and the Drug Enforcement Administration, as well as data from 13 states that are part of the Drug Abuse Warning Network.
Health officials urged physicians not to prescribe the drug unless they had experience with it, and to limit its use to areas where the benefits outweigh the risks, such as in the treatment of cancer pain or for palliative care.
In the MMWR article, the CDC researchers said that the current uses of the drug in pain treatment might be inappropriate. They pointed to a study from the FDA showing that musculoskeletal problems such as back pain and arthritis were the most common diagnoses associated with methadone use for pain in 2009. The researchers specifically urged physicians not to prescribe methadone for low back pain because studies have not shown benefits to using opioids for this condition.
Methadone also should not be prescribed for acute pain or to opioid-naive patients, and should be avoided in patients taking benzodiazepines because of the risk for severe respiratory depression, according to the researchers.
"There are plenty of safer alternatives to methadone," Dr. Frieden said. "We want to ensure that methadone remains available for appropriately treating addiction and pain and also address the thousands of overdose deaths involving methadone."
The study showed a slight decrease in methadone-related overdose deaths in 2008 and 2009, which Dr. Frieden attributed to government efforts to reduce the availability of high-dose forms of methadone and improve its labeling. But there’s still more work to do, he said.
Physicians can do their part by following guidelines for prescribing methadone and other opioids, including screening for substance abuse, he said.
CDC officials urged insurers and pharmaceutical companies to play a role as well. For example, insurers could require authorization for starting doses of methadone for pain that exceed 30 mg/day and stop including methadone on formularies as a preferred drug for the treatment of chronic noncancer pain. Health officials also called on pharmaceutical companies to introduce a low-dose formulation of methadone.
The study was conducted by researchers from the National Center for Injury Prevention and Control at the CDC.