Avoiding Accidental Overdoses when Methadone is Prescribed for Pain
FDA has issued a Public Health Advisory cautioning practitioners about avoiding overdoses when they are prescribing methadone or managing patients taking this drug.
Since the 1970s, methadone has been primarily used in treating drug abuse, but now it's also being used increasingly for the treatment of pain. FDA issued the Advisory because of reports of life-threatening adverse events and death in patients receiving methadone for pain control.
Part of the reason is that physicians prescribing methadone for pain relief may not fully understand the drug's pharmacology and potential adverse effects. For example, methadone, like other opioids, causes respiratory depression. But in addition, it can also have effects on cardiac conduction, leading to prolonged QT intervals and serious arrhythmias.
Methadone also interacts with many other drugs, some of which can slow methadone's elimination from the body and thus increase the likelihood of overdose and adverse effects related to either respiratory depression or cardiac arrhythmias.
Overdoses can also occur because methadone remains in the body much longer than the drug's analgesic effect lasts. So if a patient takes more methadone to extend the duration of pain relief, he or she may be at serious risk of respiratory depression.
The Advisory lists several recommendations for health care professionals, including closely monitoring patients on this drug, especially when starting treatment or adjusting the dose.
This should be done even for patients who are opioid-tolerant. Because many patients will be taking the methadone at home without medical supervision, much of the responsibility for avoiding overdoses rests with patients and caregivers. Because of this, FDA is working on a Medication Guide for patients, to be distributed when prescriptions for methadone are dispensed.
In the meantime, health care professionals should refer patients to the Patient Package Insert for advice on how to use the drug safely. Here's what patients should know if they take methadone for pain relief: