Methadone to treat non-oncologic neuropathic pain. Case reports.

Background and Objectives: This report includes seven patients with chronic non-oncologic neuropathic pain who have not responded to classic approaches with tricyclic antidepressant and anticonvulsant drugs. Oral methadone, a synthetic opioid similar to morphine, is referred as alternative to treat neuropathic pain due to its non-competitive antagonist action on NMDA receptors. This study aimed at evaluating methadone to treat chronic non-oncologic neuropathic pain patients who have not responded to classic approaches.
Case Reports: Seven cases in which methadone dose was titrated in subsequent visits are presented. Pain severity according to facial scale, side effects and improved functional capacity were evaluated 1, 7, 14, 30 and 180 days after treatment beginning. There has been decrease in pain severity and in the incidence of side effects, such as constipation, sedation, nausea, headache and insomnia. There has been no euphoria, sweating, myoclonia, urinary retention, decreased libido and respiratory depression.
Conclusions: Patients responded satisfactorily to low dose medication, side effects were controlled with simple measures and there has been significant functional capacity improvement. In the conditions of this study, methadone was an effective, safe and low-cost option to treat non-oncologic neuropathic pain.