Oral methadone for chronic noncancer pain: a systematic literature review of rea

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Clin J Pain. 2005 Nov-Dec;21(6):503-12.

Oral methadone for chronic noncancer pain: a systematic literature

review of reasons for administration, prescription patterns,

effectiveness, and side effects.

Sandoval JA, Furlan AD, Mailis-Gagnon A.

Comprehensive Pain Program, Toronto Western Hospital, Toronto,

Ontario, Canada.

OBJECTIVE: To assess the indications, prescription patterns,

effectiveness, and side effects of oral methadone for the treatment

of chronic noncancer pain.

METHODS: We conducted searches of several electronic databases,

textbooks and reference lists for controlled or uncontrolled studies

in humans. Effectiveness was assessed using a dichotomous

classification of " meaningful " versus " nonmeaningful " outcomes.

RESULTS: Twenty-one papers (1 small randomized trial, 13 case

reports, and 7 case series) involving 545 patients with multiple

noncancer pain conditions were included. In half of the patients, no

specific diagnosis was reported. Methadone was administered primarily

when previous opioid treatment was ineffective or produced

intolerable side effects.

Starting dose ranged from 0.2 to 80 mg/day and maximum dose ranged

from 20 to 930 mg/day. Pain outcomes were meaningful in 59% of the

patients in the uncontrolled studies. The randomized trial

demonstrated a statistically significant improvement in pain for

methadone (20 mg/day) compared to placebo. Side effects were

considered minor.

DISCUSSION: Oral methadone is used for various noncancer pain

syndromes, at different settings and with no prescription pattern

that could be identifiable. Starting, maintenance, and maximum doses

showed great variability.

The figure of 59% effectiveness of methadone should be interpreted

very cautiously, as it seems overrated due to the poor quality of the

uncontrolled studies and their tendency to report positive results.

The utilization of oral methadone for noncancer pain is based on

primarily uncontrolled literature. Well-designed controlled trials

may provide more accurate information on the drug's efficiency in

pain syndromes and in particular neuropathic pain.