Duloxetine Reduces Pain Severity in Fibromyalgia Patients

Stephanie Doyle

February 19, 2008

February 19, 2008 (Kissimmee, FL) — Results of a randomized trial suggest that duloxetine ( Cymbalta, Eli Lilly & Co) is safe and effective in the treatment of fibromyalgia
, whether depressive symptoms are also present or not.

Duloxetine could be the next drug approved by the US Food and Drug Administration (FDA) for the treatment of fibromyalgia, according to a researcher whose study was presented here at the American Academy of Pain Medicine 24th Annual Meeting.

"It has been shown that this class of medications can be very beneficial for treatment of pain and often can improve fatigue as well," Philip Mease, MD, from the University of Washington School of Medicine in Seattle, told Medscape Neurology & Neurosurgery. "This is a real boon for these patients."

The study, a 6-month randomized, double-blind, placebo-controlled, fixed-dosed trial, was the second and slightly larger trial of duloxetine hydrochloride in fibromyalgia. An application to the FDA for approval in this indication was filed in August 2007, Dr. Mease said. "We're hoping for approval sometime this year," he said.

New Indication

Duloxetine hydrochloride is a member of a class of drugs commonly referred to as serotonin and norepinephrine reuptake inhibitors (SNRIs) and previously was FDA-approved for treating major depression and managing diabetic neuropathic pain.

The recent study aimed to determine whether treatment with 120 mg of duloxetine for 3 months was effective in reducing pain severity in patients with fibromyalgia syndrome (FMS).

Two doses of duloxetine, 60 and 120 mg per day, and placebo were compared during a total of 6 months of treatment in adults. Coprimary efficacy measures included the Brief Pain Inventory Average Pain Score (APS), and the Patient Global Impressions of Improvement (PGI-I) questionnaire. Safety and tolerability were also assessed.

At 3 months, patients treated with the 120-mg/day dose showed greater improvement in change from baseline in APS score and in their end-point PGI-I score vs placebo-treated patients. At 6 months, the 120-mg/day group still exhibited greater improvement in APS change and PGI-I scores.

Coprimary End- Point Outcomes With 120 mg/day Duloxetine vs Placebo at 3 and 6 Months

Outcome Duloxetine 120 mg/d Placebo P
APS score: change from baseline to 3 mo -2.31 -1.38 < .001
APS score: change from baseline to 6 mo -2.25 -1.42 .003
PGI-I score at 3 mo 2.89 3.30 .003
PGI-I score at 6 mo 2.93 3.37 .012

The 60-mg/day group showed significant improvement compared with the placebo group on both measures at 3 months and on APS change at 6 months. At 6 months, response, defined as 50% or greater reduction from baseline in APS, was greater in both the 120-mg/day group (35.9%; P ≤ .01) and the 60-mg/day group (32.6%; P ≤ .05) compared with placebo (21.6%). Duloxetine was similarly efficacious in patients with (n = 122) or without (n = 375) major depressive disorder with regard to both coprimary end points, they note.

Discontinuation rates over 6 months were similar among the groups: 45.3% in the 60- mg/day group, 46.3% in the 120-mg/day group, and 50.0% in the placebo patients. Adverse event–related discontinuation was significantly higher in the 120-mg/day group (25.9%; P =.003) but not inthe 60-mg/day group (15.3%, P = .400) compared with the placebo patients (11.8%).

The researchers concluded that both the 60- and 120-mg/day doses are "efficacious and safe treatment options for pain associated with FMS, whether or not major depressive disorder is present."

Cause Still Unknown

"Fibromyalgia can be very difficult to treat, in part because we don't know what causes it," said Ken Follett, MD, PhD, president-elect of the American Academy of Pain Medicine, who was not involved with the study. "So some of the medications being delivered for the first time can offer some hope to patients with fibromyalgia."

Pregabalin (Lyrica, Pfizer) was approved for the treatment of fibromyalgia in June 2007.

Funding was provided by Eli Lilly & Company and Boehringer Ingelheim. Dr. Mease reports no relevant financial relationships.

American Academy of Pain Medicine 24th Annual Meeting: Abstract 109.


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