Methadone in the management of intractable neuropathic noncancer pain

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Can J Neurol Sci. 2005 Aug;32(3):340-3.

Methadone in the management of intractable neuropathic noncancer pain.

Moulin DE, Palma D, Watling C, Schulz V.

Departments of Clinical Neurological Sciences, Faculty of Medicine,

University of Western Ontario, London, Ontario, Canada.

OBJECTIVE: To evaluate the role of methadone in the management of

intractable neuropathic noncancer pain.

METHODS: A case series of 50 consecutive noncancer pain patients who

were seen at a tertiary care centre and treated with oral methadone

for a variety of intractable neuropathic pain states.

RESULTS: The mean age was 52.7 years and the mean duration of follow-

up was 13.9 months. Post-discectomy nerve root fibrosis, complex

regional pain syndrome, peripheral neuropathy and central spinal cord

pain syndromes were the most common diagnoses. Over 90% had been

treated with one or more tricyclic antidepressants and

anticonvulsants and a similar number had received other adjuvant

analgesics. All patients had failed treatment with one or more

conventional opioid analgesics (mean 2.8) at a mean maximal morphine

dose of 384 mg (or equivalents) per day. Twelve patients had failed

spinal cord stimulation. Nineteen patients (38%) did not tolerate

initial methadone titration or thought their pain was worse on

methadone. Five patients (10%) declared initial benefit but required

repetitive dose escalation and eventually became non-responders.

Twenty-six patients (52%) reported mild (4), moderate (15), marked

(6) or complete (1) pain relief and continued on methadone at a mean

maintenance dose of 159.8 mg/day for a mean duration of 21.3 months.

Fourteen patients (28%) reported improved function on methadone

relative to previous treatments.

CONCLUSIONS: Methadone appears to have unique properties including N-

methyl-D-aspartate antagonist activity that may make it especially

useful in the management of intractable neuropathic pain. This

observation needs to be tested in randomized, controlled trials.