Maintenance of the long-term effectiveness of tramadol in treatment of thepain of diabetic neuropathy

Objective: The objective of this study was to evaluate the efficacy and saf ety of tramadol in a 6-month open extension following a 6-week double-blind randomized trial. Research design and methods: Patients with painful diabe tic neuropathy who completed the double-blind study were eligible for enrol lment in an open extension of up to 6 months. All patients received tramado l 50-400 mg/day. Self-administered pain intensity scores (scale 0-4; none t o extreme pain) and pain relief scores (scale - 1-4; worse to complete reli ef) were recorded the first day of the open extension (last day of the doub le-blind phase) and at 30, 90, and 180 days. Results: A total of 117 patien ts (56 former tramadol and 61 former placebo) entered the study. On the fir st day of the study, patients formerly treated with placebo had a significa ntly higher mean pain intensity score (2.2 +/- 1.02 vs. 1.4 +/- 0.93, P < 0 .001) and a lower pain relief score (0.9 +/- 1.43 vs. 2.2 +/- 1.27, P < 0.0 01) than former tramadol patients. By Day 90, both groups had mean pain int ensity scores of 1.4, which were maintained throughout the study. Mean pain relief scores (2.4 +/- 1.09 vs. 2.2 +/- 1.14) were similar after 30 days i n the former placebo and former tramadol groups, respectively and were main tained for the duration of the study. Four patients discontinued therapy du e to ineffective pain relief; 13 patients discontinued due to adverse event s. The most common adverse events were constipation, nausea, and headache. Conclusions: Tramadol provides long-term relief of the pain of diabetic neu ropathy. (C) 2000 Elsevier Science Inc. All rights reserved.