Mar 21, 1:12 PM ET
NEW YORK (Reuters Health) – Women with fibromyalgia experienced modest improvements in their condition after taking the antidepressant Prozac (fluoxetine) for 3 months, according to the results of a recent study.
Fibromyalgia is a chronic condition, often accompanied by depression and fatigue, in which a person feels pain in the muscles and tissues surrounding the joints. While the cause of fibromyalgia is unknown, researchers have found pain-processing abnormalities in the spines and brain stems of those with fibromyalgia.
About 2% of the US population is estimated to suffer from fibromyalgia, mostly women aged 50 years and older.
While previous studies of the effectiveness of antidepressants in patients with fibromyalgia have had mixed results, a report published in The American Journal of Medicine suggests that the dosages used in those studies may have been too low.
In the current study, Dr. Lesley M. Arnold of the University of Cincinnati Medical Center in Ohio and colleagues evaluated 51 non-depressed women with fibromyalgia. Twenty-five of the women took an average of 50 milligrams of Prozac per day for 3 months while the other 26 took an inactive placebo for the same time period.
At the beginning of the study, and in the 2nd, 4th, 6th, 8th and final week of the study, the patients completed questionnaires assessing their fibromyalgia symptoms and pain.
An improvement of 25% or more in overall symptoms was observed in 8 (32%) of the 25 women taking Prozac compared with only 4 (15%) of the women who took a placebo, the report indicates.
In addition, 56% of the Prozac takers had a 25% or better improvement in pain as measured by a standardized questionnaire compared with 15% of those who took the placebo, the investigators found.
A person is diagnosed with fibromyalgia if he or she has tenderness in at least 11 of 18 specific trigger points, including the hip, elbow, knee, the neck at the base of the skull and midway between the neck and shoulder. In the current analysis, no effect of antidepressants on pain at patients’ trigger points was seen.
Arnold and colleagues point out that due to the study’s short duration, the results may not be generalizable to longer time periods.
In an accompanying editorial, Dr. Patrick G. O’Malley writes that “most symptom-based studies define a greater than 50% improvement in symptoms as clinically significant. Thus, using only 25% improvement to define success may be overstating the efficacy of fluoxetine in fibromyalgia. Clearly, this is not a therapy that had a dramatic effect on outcomes in this sample.”
The editorialist concludes that “it is safe to say that antidepressants, including SSRIs, are effective in treating patients who have such symptom syndromes as fibromyalgia, but many questions remain as to why, how much, which, and how long.”
SSRIs, or selective serotonin reuptake inhibitors, are a class of antidepressant drugs–including Prozac–that increase levels of the brain chemical serotonin.
Eli Lilly, the pharmaceutical company that makes Prozac, funded the study.
SOURCE: The American Journal of Medicine 2002;112:191-197, 237-238.