Methadone: A Closer Look at a Controversial Pain Therapy

Author: Mary Lynn McPherson

Mary Lynn McPherson, PharmD, BCPS, CPE, FASPE

I think the important thing with methadone is safety first. Even though I’m a big methadone fan, I don’t think everyone is an ideal candidate for methadone therapy. I think we have to have a patient who’s very reliable, who will follow the plan of care, who will follow the directions, someone who would not abuse the medication as prescribed by their physician or NP or PA. I think there are some very important safety standards. For example, we do have to worry also about the risk for cardiac arrhythmias. A patient who has hypokalemia, hypomagnesaemia, people who have congenital QTC prolongation, people who have unexplained syncope, again, the patients who are unreliable and will not follow the plan of care, we have to be very careful.

When you’re switching to methadone from a different opioid, there are many different published methods for doing conversion calculations. All the methods work because the most important thing is when you come up with that magical number, you have to temper it with clinical judgment. You have to use your clinical acumen to decide if this is an appropriate dose with this patient, and then monitor the patient intensively. In my hospice, for example, we have the nurse go out every day for the first five days after starting or switching to methadone therapy and then, again, with dosage increases as well. The savvy practitioner will also be very familiar with the numerous drugs that interact with methadone. There are many drugs that will induce the metabolism of methadone giving you a lower serum concentration. Then there are many, many medications that will inhibit the metabolism of methadone increasing the methadone serum concentration.

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