Fibromyalgia is a common health problem that causes widespread pain and tenderness (sensitive to touch). The pain and tenderness tend to come and go, and move about the body. Most often, people with this chronic (long-term) illness are fatigued (very tired) and have sleep problems. And, the disease has been linked with mood disorders, such as depression. In fact, 50 to 70 percent of people with fibromyalgia report a lifetime history of depression, and approximately 25 percent have a history of taking antidepressants.

Pregabalin is approved for the treatment of fibromyalgia in the United States, Japan, and other countries. But, because prior pregabalin/fibromyalgia studies excluded the use of antidepressants in treatment, information about the effectiveness and safety of pregabalin for the treatment of pain in people with fibromyalgia who are being treated with antidepressants for their depression is lacking.

"Depression is common in patients with fibromyalgia," explains Lesley M. Arnold, MD; professor of psychiatry and behavioral neuroscience; University of Cincinnati College of Medicine, Cincinnati, Ohio; and lead investigator in the study. "Many patients present to their doctor for treatment of fibromyalgia pain already taking antidepressants for their depression. This is the first study to evaluate the efficacy and safety of pregabalin for treatment of fibromyalgia pain in patients who are also taking antidepressants for depression."

With this in mind, researchers completed a study to determine if pregabalin would affect pain levels in people with fibromyalgia who were also being treated for depression. The study included 197 patients who were, on average, 50 years of age and overwhelmingly white females. To join the study, patients had to meet the 1990 American College of Rheumatology Criteria for Fibromyalgia (including manual tender point exam), have an average pain level of at least four out of 10 on the Numeric Rating Scale, (0 = no pain and 10 = worst possible pain), have a documented diagnosis of depression and be taking stable dose of an antidepressant medication -- either a selective serotonin reuptake inhibitor (such as Celexa®, Lexapro®, Prozac®, Paxil® or Zoloft®) or a serotonin-norepinephrine reuptake inhibitor (such as Cymbalta®, Effexor®, or Pristiq®). The antidepressant treatment was continued throughout the study.

Patients were on study treatment for a total of 14 weeks. There were two six-week treatment periods when patients received either pregabalin or placebo, with a two-week break in between these periods. Each patient was randomly assigned to receive either pregabalin in the first six weeks, then placebo in the last six weeks, or to receive placebo first, then pregabalin. None of the patients knew which treatment they were receiving at any point in the study. Pregabalin was started at a dose of 150mg per day and within three weeks was increased to 300-450mg per day based on patient response; this dose was continued for the rest of the treatment period.

During the study, 193 patients received at least one dose of study medication; 181 patients received at least one dose of pregabalin, and 177 received at least one dose of placebo. At the beginning of the study, the average pain score amongst participants was 6.7. The average pain score dropped to 4.84 after treatment with pregabalin and to 5.45 after treatment with placebo. Pregabalin treatment significantly improved patients' pain compared to placebo.

Side effects were reported in 77.3 percent of those on pregabalin and 59.9 percent of those on placebo. For pregabalin treatment the most common events were dizziness (28.2 percent) and drowsiness (19.9 percent). A total of four serious adverse events were reported, three of which occurred in those on pregabalin and one on placebo; the researchers concluded these events were not related to the treatment. Of those taking pregabalin, 6.1 percent did not complete the study due to a side effect, compared with 3.4 percent of those taking placebo.

"The results of this study demonstrate that pregabalin is safe and effective in reducing fibromyalgia pain in patients who are also taking an antidepressant to treat their depression," says Dr. Arnold.

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Materials provided by American College of Rheumatology (ACR). Note: Content may be edited for style and length.