Eli Lilly reported positive results from a phase III trial of Cymbalta (duloxetine) for the treatment of fibromyalgia. Cymbalta is Lilly’s serotonin and norepinephrine reuptake inhibitor (SSNRI), approved in the U.S. for major depression and diabetic (peripheral neuropathic) pain. Merrill Lynch has forecasted the product could reach worldwide sales of $2.2 billion in 2008.

This randomized, placebo-controlled trial enrolled subjects with fibromyalgia, with or without depression, who received Cymbalta (60 mg or 120 mg) or placebo. They were subsequently measured at three and six months for improvements on the Brief Pain Inventory Average Pain Score (BPI) and the Patient's Global Impression of Improvement questionnaire (PGI- I). At three months, subjects in both Cymbalta arms showed significantly greater reduction in pain and improvement in PGI-I scores compared with the placebo group.

In addition, more subjects treated with Cymbalta (both 60mg and 120 mg) showed significantly greater reduction in pain as measured by a 30% improvement in baseline BPI scores (50.7% and 52.1%, respectively), compared with those taking placebo (36%).

At the end of the six-month trial, more subjects treated with both doses of Cymbalta showed a response to treatment, defined as a 50% reduction of baseline BPI scores, (32.6% and 35.9%, respectively), compared with subjects taking placebo (21.6%).

A supplemental new drug application (sNDA) for the treatment of fibromyalgia is currently under review by the FDA.

Fibromyalgia syndrome is a chronic, but sometimes debilitating, musculoskeletal pain and fatigue disorder. The disorder affects about 3 - 6 million people in the U.S. each year. Its cause is not known.