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09:16

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Published on: January 22, 2016

Myoclonus associated with high-dose parenteral methadone

Shiho Ito1, Solomon Liao

  • 1VITAS Innovative Hospice Care, Orange County, Orange, California, USA.

Journal of Palliative Medicine
|August 22, 2008
PubMed

Insights

High-dose methadone, especially when injected, can cause neuroexcitation like myoclonus in cancer patients. Adjusting the dose and administration route effectively managed this side effect, offering pain relief without movement disorders.

Area of Science:

  • Palliative Care
  • Neuropharmacology
  • Oncology

Background:

  • Methadone is widely used for pain management and is generally considered non-neuroexcitatory.
  • Its clinical use is expanding, necessitating a thorough understanding of its side effect profile.

Observation:

  • Two cancer patients receiving high-dose parenteral methadone in hospice care developed myoclonus.
  • Myoclonus, or involuntary muscle twitching, emerged as a potential adverse effect of high-dose methadone administration.

Findings:

  • The observed myoclonus was potentially linked to the high dosage and/or intravenous route of methadone administration.
  • Reducing the methadone dose and switching to an alternative route of administration resolved the myoclonus while maintaining effective pain control.
  • Potential mechanisms involve methadone-induced redistribution of receptor saturation at N-methyl-D-aspartate (NMDA) and delta receptors.

Implications:

  • This suggests that methadone may possess neuroexcitatory properties under specific conditions, challenging previous assumptions.
  • Parenteral administration and high doses of methadone warrant careful monitoring for potential neuroexcitatory side effects in palliative care.
  • Ketamine may serve as an alternative pharmacological option for managing intractable pain in patients experiencing methadone-induced myoclonus.

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