A Double Blind Randomized Controlled Trial Examining the Efficacy of Methadone in the Treatment of Chronic Neuropathic Pain

INTRODUCTION: There is an important need for inexpensive drugs that treat neuropathic pain. Early research suggests that methadone may be a good, inexpensive drug to treat neuropathic pain. Methadone is available in a low cost powder that is easily prepared for different routes of administration. This study will look at the effect and safety of methadone compared to the regular treatment of morphine for the treatment of chronic neuropathic pain. OBJECTIVES: First we want to determine if methadone is effective and safe for the treatment of neuropathic pain. Since a placebo control group would be unethical, the proposed comparator will consist of the gold standard conventional treatment, controlled release morphine. We will compare methadone to controlled-release morphine with regard to how it affects the level of pain and extent of side effects. Next we want to examine safety as well as to determine whether methadone leads to improvements in physical and emotional functioning, and participants' satisfaction with the treatment. METHODS: A double blind, randomized trial comparing methadone and controlled release morphine is proposed. After a 1-week, participants will be randomly assigned to either methadone or controlled release morphine and will gradually build to a dose at which they receive adequate pain relief without unacceptable levels of side effects. This 5-week phase will be followed by a 6-week dose phase and then a 4-week tapering off phase. Study drug: The study drug is methadone supplied in 2.5 mg tablets. The comparator will consist of controlled release morphine in 10 mg tablets. The dose of each will range from 1-12 tablets taken every 12 hours (dose ranges methadone 5-60 mg/day, controlled release morphine 20-240 mg/day). Setting: This is a 3-site study involving pain clinics in Halifax, Nova Scotia; London, Ontario; and Calgary, Alberta.