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Blog articles are provided as informational purposes only and are not intended to constitute medical advice. Medication protocols are subject to patient’s medical provider’s authorization.

 

 

Methadone was first developed in Germany in the 1930s and was used extensively during World War II as an alternative to morphine during shortages. Over the past twenty years, methadone has experienced a revival due to its unique characteristics, versatile administration, and utility in managing nociceptive and/or neuropathic pain in hospice and palliative care (Figure 1).

Conversion to Methadone from Another Opioid:

Converting from one oral (PO) opioid to methadone is a complex process, especially if the patient is at a very high dosage. However, a recent expert consensus report by McPherson and team entitled, Safe and Appropriate Use of Methadone in Hospice and Palliative Care, provides a more streamlined approach to dosing conversions (Figure 2). Please note that PO methadone dosing conversions are not linear; this means that the conversion ratio increases as the oral morphine dose (or equivalent amount of other opioid) increases. Compare that to a linear conversion, where the ratio of one opioid to the other will always be the same (e.g. always 1:5 or always 1:10), regardless of the starting dose of the initial opioid. In a non-linear conversion (as with methadone), use of high but ineffective doses of previous opioid(s) may result in overestimation of the equivalent methadone dose, so the initial total methadone dose should generally not exceed 40mg per day. Methadone dosing conversions are also not bi-directional; this means that the same conversion factor used to convert from an opioid to methadone is not used to convert from methadone back to the initial opioid. A consultation with a clinical pharmacist that specializes in pain management or hospice and palliative care is generally recommended when transitioning to or making significant changes to a methadone regimen, and “methadone checks” to monitor the safety and efficacy of the patient’s methadone therapy are generally recommended for the first 5-7 days after starting or making a change to a methadone regimen.

Appropriate Patients for Methadone Use (or Non-Use):

Despite its unique characteristics and advantages, methadone is not appropriate for everyone. With a few exceptions, patients with a prognosis of one week or less generally should not convert completely over to methadone since it may take seven or more days to reach steady state and achieve long-acting effects. If a patient lives alone and is unreliable/noncompliant, then methadone is generally not recommended. Likewise, if a patient has poor cognitive function and does not have a reliable caregiver, then methadone is generally not recommended either. The following patient populations are at increased risk of adverse outcomes or toxicity, but may still be considered for methadone therapy, if appropriate: those with significant cardiac disease (especially in the presence of hypokalemia, a pacemaker or other risks for QTc prolongation), severe liver disease, obstructive or central sleep apnea, multiple risk factors for toxicity (e.g. clinical instability, multiple transitions in care, history of transplant, etc.), multiple interacting medications, and/or a history of substance misuse/abuse. Ultimately, each patient should be assessed on a case-by-case basis prior to starting methadone to ensure that the benefits outweigh the risks.

 

Written by: Brett Gillis, Pharm.D.

 

References:

  1. Chary S, Palat G. Practical guide for using methadone in pain and palliative care practice. Ind J Pal Care 2018; 24(1):21-29.
  2. Hamid K. Pain management: the use of methadone in hospice and palliative care. ProCare 2018.
  3. McPherson ML, Walker KA, Davis MP et al. Safe and appropriate use of methadone in hospice and palliative care: expert consensus white paper. J Pain Sympt Mgt 2019; 57:635-647.
  4. Methadone monograph. CESAR Center for Substance Abuse: University of Maryland 2016.
  5. Speer K. Safe and effective methadone use in hospice patients. ProCare 2019.

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