Paroxetine Controlled Release May Relieve Fibromyalgia Symptoms

Paula Moyer, MA

October 12, 2004

Oct. 12, 2004 (Stockholm) — Patients with fibromyalgia get relief of their symptoms from a controlled-release formulation of paroxetine (Paxil), according to investigators who presented their findings here at the 17th congress of the European College of Neuropsychopharmacology.

These findings could represent a turning point for patients, because their symptoms typically do not respond to other pharmaceutical strategies, said principal investigator Ashwan A. Patkar, MD, in a presentation. "Most patients in the treatment group had a 25% or greater reduction in the impact of fibromyalgia compared to those on placebo," said Dr. Patkar, an instructor in the Department of Psychiatry and Human Behavior at Thomas Jefferson University in Philadelphia, Pennsylvania. "Therefore, paroxetine may have a role in the treatment of fibromyalgia."

Dr. Patkar and coinvestigators investigated the efficacy and tolerability of paroxetine controlled release for fibromyalgia in a 12-week randomized, placebo-controlled, double-blind design. They screened 180 patients and randomized 116 to receive paroxetine controlled release or placebo for 12 weeks. Of the 74 patients excluded, nearly half (48%) had a current depressive disorder.

Of the subjects, 94% were women and 71% were white. They were an average of 48 years old, with 58% married and 63% employed. The investigators found no significant differences in baseline characteristics between patients in the drug and placebo groups. Those in the treatment group received doses of 12.5 mg to 62.5 mg per day, with an average dose of 32.3 mg per day.

The study design defined the primary efficacy measure as at least a 25% reduction in scores on the Fibromyalgia Impact Questionnaire (FIQ) from randomization to the study's end. The investigators also used the Clinical Global Impression-Improvement (CGI-I) and Clinical Global Impression-Severity (CGI-S) instruments, as well as the visual analogue scale (VAS) for pain.

Of the 116 enrollees, 85 (73%) completed the study. Of these, 57% in the treatment group had at least a 25% reduction in the FIQ compared with 33% in the placebo group ( P = .016). When the investigators used the FIQ score in a survival analysis, results showed that controlled-release paroxetine was superior to placebo during the study period ( P = .001).

The treatment group had an average improvement of 58% on CGI-I scores compared with an average improvement of 25% in the placebo group ( P = .002). However, the investigators saw no significant differences between the drug and placebo groups on their rates of 25% and 50% reductions in their VAS scores. Despite the similarity on this measure, the lessened impact of the disease in the treatment group shows the drug's potential in fibromyalgia, Dr. Patkar said.

The adverse-effect profile was generally mild, with 31% in the treatment group and 6% in the placebo group reporting drowsiness ( P = .012). Patients in the treatment group also were more likely to have dry mouth (36% of paroxetine patients vs 9% of placebo patients; P = .009).

ECNP 17th Congress: Abstract P.3.037. Presented Oct. 11, 2004.

Reviewed by Gary D. Vogin, MD


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