Methadone in the treatment of neuropathic pain

Abstract

Background: Methadone, being an N-Methyl-D-Aspartate receptor antagonist, may have a potential role in the treatment of neuropathic pain. Objectives: To evaluate the effect of methadone in the treatment of neuropathic pain and to estimate the possible dose ranges needed for pain control. Methods: Methadone was offered as a treatment option to consecutive cancer and noncancer patients with neuropathic pain. Pain intensity was measured by the visual analogue scale (VAS) (0-10 cm where 0 = no pain and 10 = worst possible pain). Mechanical allodynia and paroxysmal (shooting) pain were assessed clinically. All assessments were collected prospectively before treatment and once a stable dose of methadone was reached. Results: A total number of 18 patients met our inclusion criteria. The mean pretreatment VAS ± SD was 7.7±1.5 cm and this dropped significantly to 1.4±1.7 cm on a stable dose of methadone (P<0.0001). Nine of 13 patients (70 %) had a complete resolution of mechanical allodynia and all eight patients (100%) with shooting pain reported a complete response. The median stable dose of methadone was 15 mg per day. Conclusion: Methadone at relatively low doses seems to be useful in the treatment of neuropathic pain.