SHOULD WE CONSIDER METHADONE THERAPY FOR PAIN MANAGEMENT?
In recent years, health care professionals have been reluctant to prescribe methadone as a means of pain management. For many reasons, methadone has sort of a stigma attached to it because it is often used as a treatment for addiction. Sometimes, without having the full picture, patients and their families reject the idea of methadone, but, before we throw the baby out with the bath water, let’s look into it a little further.
What are opioids?
For thousands of years, in fact as long ago as 3400 BC, the milky sap of the opium poppy plant has been harvested to create opium, a heavy-scented addictive drug that contains morphine, codeine, and other alkaloids used in medicine. Collectively, these drugs that are cultivated from the dried ruminates of the poppy plant are referred to as opioids. The most active substance in opium is the analgesic (pain-relieving drug) called morphine, named after Morpheus, the Greek god of dreams.
What are opiates?
Opiates (such as OxyContin and fentanyl), which are also used for pain relief, are the synthetic version of the opioids and are created in a laboratory. Oxycodone does come from the poppy plant, but it is refined in the laboratory to such an extent that it is referred to as a semi-synthetic opiate. Methadone, which has a much longer half-life than oxycodone, is an opiate; it is a fully synthetic opioid.
Advantages of methadone pain therapy.
So, why are so many clinicians hesitant to use methadone as their preferred method of pain management? Is it because of the stigma that associates methadone with treatment for heroin addiction? In the interest of casting off that stigma, let’s look at a few advantages of methadone therapy. First of all, methadone is quite inexpensive compared to other opioid pain therapies. It is very effective in relieving chronic pain and neuropathic pain. It is available in tablet or liquid form – both of which are long acting. In fact, methadone is the only long-acting opioid elixir. It has no active metabolites, so, unlike many other analgesics, the body does not metabolize it into a modified form which continues to produce effects in the body. And, a fact that most patients can appreciate, it has lower incidence of constipation than other opioid pain therapies.
Disadvantages of methadone pain therapy.
Besides methadone’s reputation as a treatment for heroin addicts, there are a few clinically factual reasons some clinicians may not elect methadone pain therapy for their patients. For one thing, dosages vary widely among patients. Also, methadone has a long half-life. In other words, it takes a long time for the methadone in a patient’s body to be reduced to half. Consequently, it makes titration difficult. In other words, it can be difficult to measure accurately the amount of methadone needed after the initial dose. And, methadone has a complex equianalgesic conversion; it is a rather complex process to calculate doses among other analgesics.
Who could benefit most from methadone therapy?
Certain patients are most likely to benefit from methadone therapy. For instance, patients with renal impairment and neuropathic pain seem to respond well to methadone. Patients whose pain is still uncontrolled after other opioid regimens also benefit from the switch to methadone therapy. Also, patients who suffer from opioid-induced adverse effects, such as hallucinations, are often relieved of those effects. Some patients who need long-acting pain control require liquid formulations, and methadone is available in liquid form. Certainly, patients with limited incomes - patients who may be unable to pay for more expensive pain management – would definitely benefit from the less expensive methadone therapy.
Patients for whom methadone therapy is not appropriate.
Methadone therapy may not be appropriate for patients who have been given a very short prognosis because it may take several days to a week for the medicine to take full effect or reach steady-state. Also, methadone would not be appropriate for patients with a history of syncope or arrhythmias. Patients who live alone, who have poor cognitive function, who are unreliable or unable to comprehend medication instructions might not be the best candidates for methadone therapy. Most importantly, methadone therapy may not be ideal for patients who are receiving other drugs that could potentially increase the QT interval.
Jaymie Wilson, MSN, APRN-CNP, AGACNP-BC
Vice President of Operations – PDC Rx