Antidepressant Duloxetine aids in improving symptoms, relieving pain in Fibromyalgia
DGNews
NEW YORK, NY
-- September 9, 2004 -- Fibromyalgia is a chronic, incapacitating
musculoskeletal disorder. Nearly six times more common in women than in men, fibromyalgia
is marked by widespread body pain and muscle tenderness, often accompanied by
headaches, sleep disturbances, and fatigue. While its cause remains a mystery,
fibromyalgia has been linked to abnormalities in the brain's neurotransmitters,
serotonin and norepinephrine--chemicals key to mood and widely recognized for
their role in depression. Not all patients with fibromyalgia, however, have
depression or respond to antidepressants. Treatment studies of the other types
of antidepressant drugs, including selective serotonin uptake inhibitors and
tricyclic agents, have had mixed results.
A new and different antidepressant, duloxetine, works by inhibiting the
reuptake of both serotonin and norepinephrine. In a recent clinical trial
conducted for the treatment of fibromyalgia--one of the largest
ever--duloxetine was shown to reduce pain and improve a range of disease
symptoms, significantly and safely. The results, published in the September
2004 issue of Arthritis & Rheumatism, offer the promise of relief
for women with fibromyalgia.
"Our results suggest that duloxetine improves pain and tenderness, the
hallmark characteristics of fibromyalgia," states Lesley M. Arnold, M.D.,
who coordinated the research at 18 centers, including the University of Cincinnati College of Medicine, Indiana University Medical School, and Harvard Medical School. "The effect of duloxetine on the reduction of pain," Dr.
Arnold further notes, "appears to be independent of its effect on
mood."
To test duloxetine's effectiveness on the range of symptoms, researchers
recruited 207 patients, all meeting the American College of Rheumatology
criteria for fibromyalgia. Like the majority of those with this disease, the
majority of the participants--89 percent--were women. 87 percent of the
subjects were Caucasian and the mean age was 49. Just over a third of the
patients--38 percent--had been diagnosed with depression. On a random basis,
the patients were prescribed one of two treatments for a course of 12 weeks. About
half, 104 individuals, received 60 milligrams of duloxetine twice a day. The
remaining 103 patients were given a placebo. Both groups were evaluated and
scored, using the Fibromyalgia Impact Questionnaire and other standard
measures, for improvements in their condition.
In various measures of disease--from pervasive pain to tiredness to
tenderness--the female fibromyalgia patients treated with duloxetine improved
significantly over those treated with a placebo. One of the most dramatic
changes was in the reduction of the number of tender points--places on the body
where it hurts to touch--and the increase of pressure pain threshold. Women
with or without depression receiving duloxetine benefited emotionally and
physically, reporting improvements in general mood, ability to function, and
overall enjoyment of life.
For the study's 23 men, however, duloxetine did little to change their
condition. Although researchers reported some evidence of improvement in tender
point measures among duloxetine-treated men over their placebo-treated
counterparts, it was not statistically significant. "The reasons for the
sex differences in response are unclear," Dr. Arnold observes. "Because
the male subgroup was small, reflecting the much higher prevalence of
fibromyalgia in women, the results of the study may not be generalizable to all
men with fibromyalgia. There may also be sex differences in fibromyalgia that
affect treatment response."
As Dr. Arnold notes, further research is needed on larger samples of not only
men but also other groups with fibromyalgia to evaluate duloxetine's
effectiveness.
Duloxetine (Cymbaltaź) is indicated by the FDA for the treatment of major
depressive disorder and is not indicated for the treatment of fibromyalgia.