Choose methadone over morphine

Methadone – Isn’t this a drug for heroin addicts?

I’m used to hearing this from skeptical patients and families when I tell their doctor that methadone has been ordered for pain relief. While methadone is indeed used to treat narcotic withdrawal symptoms, methadone is also a very effective medication for moderate to severe pain.

Morphine has earned the title of the gold standard in pain control due to its effectiveness, ease of administration, and low cost, compared to all other opioids. If morphine is so good, why do we use methadone?

If we’re going to start comparing methadone and morphine, we need to start with the fundamentals of pain. Pain can be divided into two physiological explanations: nociceptive and neuropathic. Nociceptive pain is usually caused by tissue damage (somatic pain) or internal organ damage (visceral pain). Neuropathic pain is caused by injury or damage to the nerves in the central nervous system or peripheral body.

We are lucky that opioid receptors in the brain allow our bodies to respond to opioid painkillers. Most of these receptors are classified as mu and delta receptors, and a smaller percentage are N-methyl D-aspartate (NMDA) receptors. Nociceptive pain is mainly mediated by mu receptors, and neuropathic pain is mediated by delta and NMDA receptors; morphine binds only to mu receptors, while methadone binds to mu, delta, and NMDA. Morphine is excellent at treating many types of pain, but because it binds to 100 percent of opioid receptors, methadone may do a better job.

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Opioid toxicity and side effects

Opioids such as morphine produce metabolites when they are broken down in the body. These metabolites can build up in the body and cause symptoms of opioid poisoning. Opioid toxicity is essentially an overdose of opioids that results in toxic levels in the body and causes symptoms such as irritability, hallucinations, tremors, and drowsiness.​​​

Dose-related deaths from methadone have been reported in patients with respiratory depression, although not as common as with other opioids.

Common side effects of opioids include constipation, nausea and vomiting, drowsiness, itching, confusion, and respiratory depression (difficulty breathing). Many patients reported a reduction in adverse effects after switching from another opioid to methadone.

The benefits of methadone

Methadone is more effective than morphine in treating pain and usually causes fewer side effects; another benefit of methadone is that it has an extended half-life. Half-life is the amount of time it takes for half the amount of a drug to be metabolized or eliminated by normal biological processes. Because of this extended half-life, methadone has an analgesic effect of 8 to 10 hours, while conventional non-extended-release morphine provides pain relief for only 2 to 4 hours. This means that patients are given less frequently, usually two or three times a day.

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In addition, methadone is extremely cost-effective. A typical one-month supply of methadone costs about $8, while morphine often costs more than $100. Other opioids, such as OxyContin and fentanyl, will be more expensive.

Barriers to methadone use

You may find yourself wondering why you don’t use methadone more often.

In the United States, methadone prescription is restricted to professionals who are trained and licensed to dispense.

Due to methadone’s extended half-life, it slowly builds up in the body and may take 5 to 7 days to stabilize. During this period, patients need to be closely monitored for signs of toxicity. This is usually not a problem for patients in palliative or hospice care, as they are already being watched closely and generally have access to nurses and doctors 24 hours a day. A typical doctor’s office does not have the training or ability to monitor patients closely. It is usually limited to licensed opioid treatment programs or licensed inpatient units.

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Other barriers are physician education and patient reluctance. Methadone is still widely known as a drug addict’s drug. The stigma is slowly dissipating as doctors continue to educate their peers about its benefits, and the public sees more and more patients in remission.