Pregabalin for Patients with Fibromyalgia Also on Antidepressants

San Diego—In patients with fibromyalgia on antidepressants for comorbid depression, treatment with pregabalin safely and effectively reduces pain severity, according to the first study to examine this combination of medications for fibromyalgia and depression.

“In fibromyalgia patients with comorbid depression currently on a stable dose of an antidepressant medication, pregabalin significantly reduced pain severity compared with placebo,” said Lesley M. Arnold, MD, professor of psychiatry and behavioral neuroscience, University of Cincinnati College of Medicine, lead investigator on the study, who presented the findings at the ACR/ARHP meeting.

According to Dr. Arnold, the significant pain reduction was found as early as the first week of treatment and was maintained throughout the study. Although pregabalin is approved for treatment of fibromyalgia in several countries, there is no data on the safety and efficacy of this concomitant use.

To fill that gap, Dr. Arnold and colleagues conducted the 2-way crossover, double-blind, placebo-controlled study in which 197 patients with fibromyalgia with co-depression were randomized to receive either placebo or pregabalin. Patients on pregabalin were started at a dose of 150 mg per day, which was increased to 300 mg to 450 mg per day within 3 weeks based on patient response.

The study included two 6-week treatment periods, with a 2-week break between periods to allow for treatment tapering and placebo washout. Patients were randomly assigned to receive pregabalin during the first 6 weeks and then switched to placebo in the second 6 weeks, or vice versa. Patients were blinded to the treatment arms.

All patients included in the study were >18 years of age, met the 1990 American College of Rheumatology criteria for fibromyalgia, had a mean numeric rating scale pain score of >4, a documented diagnosis of depression, and were receiving treatment with a stable dose of a single selective serotonin reuptake inhibitor (SSRI) or serotonin-norepinephrine reuptake inhibitor (SNRI).

Of the 197 patients enrolled in the study, most were female (93%) and white (94%), with a mean age of 50 years. At baseline, 53.2% were on an SSRI, 47.7% on an SNRI, and the mean pain score was 6.7.

Overall, 181 patients received at least 1 dose of pregabalin and 177 received placebo. Patients remained on stable antidepressant therapy throughout the study. To assess the efficacy of pregabalin, the investigators measured the mean pain score based on the mean of the last 7 daily pain scores.

The study found that patients treated with pregabalin had a significantly lower least squares (LS) mean pain score from the baseline score of 6.7 compared to placebo (4.84 vs 5.45), representing a LS mean difference of -0.61 (95% confidence interval, -0.91--0.31; P=.0001).

Overall, 77.3% and 59.9% of patients receiving pregabalin and placebo, respectively, reported treatment-emergent adverse events. Dizziness and somnolence were the most frequent adverse events reported with pregabalin (28.2% and 19.9%, respectively). Of the 4 serious adverse events reported, none were considered to be treatment related. Patients who discontinued treatment due to adverse events included 6.1% of patients receiving pregabalin and 3.4% of patients receiving placebo.

Dr. Arnold said that the findings of this study may not generalize to all patients with comorbid depression and fibromyalgia because of study limitations, which include exclusion of patients with other medical or psychiatric illnesses and patients that required excluded medications, such as those to treat insomnia.