Randomized placebo-controlled trial of duloxetine for central pain in multiple sclerosis

Abstract

Background: Pain is common in multiple sclerosis (MS). Duloxetine has a potential therapeutic role in treating MS-related pain. Methods: Thirty-eight MS patients were randomized 1:1 to receive duloxetine (n = 18) or matched placebo (n = 20). The dosing regimen was 30 mg daily for 1 week, then 60 mg daily for 5 weeks. The primary outcome measure was change in worst pain for week 6 relative to baseline recorded on a daily pain diary. Results: Of 38 randomized patients, 14 (78%) patients randomized to duloxetine and 18 (90%) randomized to placebo completed treatment per protocol. These participants had an average age of 55.5 years, 25% were male, and 66% had relapsing-remitting MS (RRMS). Baseline characteristics were similar. Discontinuations were due primarily to drug intolerance. Among those who completed treatment, worst pain at 6 weeks was reduced by 29% (±20%) for duloxetine versus 12% (±18%) for placebo (P = .016). Average daily pain at 6 weeks was reduced by 39% (±29%) in the duloxetine group compared to 10% (±18.8%) in the placebo group (P = .002). There were no significant changes (week 6 vs. baseline) or between-group differences for subject global impression, Beck Depression Inventory, 36-item Short Form Health Status Survey (SF-36), or sleep quality score. Conclusions: Fewer patients could tolerate duloxetine compared to placebo. Among patients who completed 6 weeks of treatment, there were significant reductions in average and worst daily pain scores with duloxetine compared to placebo. This study suggests that duloxetine has a direct pain-relieving effect in MS.