Myoclonus associated with high-dose parenteral methadone.
Methadone is generally believed to be devoid of neuroexcitatory properties, and its use is increasing. This paper reports two cases of myoclonus with high-dose parenteral methadone in patients with cancer under hospice care. This side effect may be dose related and/or due to the parenteral route of administration. Reduction of the dose and change of route was sufficient to eliminate the myoclonus while maintaining an adequate pain control. Possible mechanisms for methadone causing myoclonus include a redistribution of receptor saturation in the N-methyl-D-aspartate (NMDA) and delta receptors. Ketamine may be an option for patients with intractable pain who develop methadone-induced myoclonus.
Ito
Shiho
S
VITAS Innovative Hospice Care, Orange County, Orange, California, USA.
Liao
Solomon
S
D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D005260:Female; D017051:Hospice Care / Q000379:methods; D006801:Humans; D008297:Male; D008691:Methadone / Q000008:administration & dosage / Q000009:adverse effects*; D008875:Middle Aged; D009207:Myoclonus / Q000139:chemically induced* / Q000188:drug therapy; D009369:Neoplasms / Q000150:complications / Q000188:drug therapy / Q000473:pathology; D010148:Intractable Pain / Q000188:drug therapy* / Q000209:etiology; D010166:Palliative Care / Q000379:methods
D000701:Analgesics, Opioid; D008691:Methadone