Controlled-release paroxetine improves symptoms in fibromyalgia

Last Updated: 2007-05-25 13:07:10 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Controlled-release paroxetine is safe and improves symptomatology in patients with fibromyalgia without current mood or anxiety disorders, according to findings published in the May issue of the American Journal of Medicine. However, it does not reduce pain.

"Meta-analyses of randomized, controlled trials have found that antidepressants are effective in fibromyalgia, although it is unclear whether this effect is independent of depression," write Dr. Ashwin A. Patkar, of Duke University Medical Center, Durham, North Carolina, and colleagues.

In a 12-week, randomized, double-blind, placebo-controlled study, the researchers examined the safety and efficacy of paroxetine controlled release (12.5 to 62.5 mg/day). Included in the study were 116 subjects with fibromyalgia free of current major depression and anxiety disorders. The primary outcome measure was the proportion of responders, where response was defined as a 25% or greater reduction in scores on the Fibromyalgia Impact Questionnaire (FIQ) from randomization to end of treatment.

Secondary outcome measures included changes in FIQ scores from randomization to end of treatment, Clinical Global Impressions-Improvement (CGI-I) and Severity (CGI-S) scores, Visual Analogue Scale for pain scores, number of tender points, and scores on the Sheehan Disability Scale (SDS).

The mean dose of paroxetine controlled release was 39.1 mg/day. Significantly more patients treated with paroxetine responded than those treated with placebo (56.8% versus 32.7%, respectively; p = 0.016). A significant reduction in the FIQ total score was observed in the paroxetine group compared to the placebo group (p = 0.015). Improvements in CGI-I score were also significantly greater in the paroxetine group compared to placebo (p < 0.05). The improvements in the other secondary outcome measures were not significantly different between the groups.

Overall, 38 (66.5%) patients in the paroxetine controlled release group and 34 (58.6%) in the placebo group reported a treatment-related adverse event. The most frequently reported adverse events in the paroxetine group were drowsiness, dry mouth, female genital disorders, ejaculatory problems, impotence, anxiety, and blurred vision.

"Paroxetine controlled release failed to separate from placebo on the pain or tender point scores," Dr. Patkar's team concludes. "Among symptoms of fibromyalgia, tender points seem to be least likely to respond to antidepressants, and symptom reduction may not be associated with tender point improvement."

Am J Med 2007;120:448-454.