Fibromyalgia remains a poorly understood and hard-to-treat disorder, characterized by widespread pain with no clear cause. Other commonly reported symptoms include fatigue, sleep problems, and depressed mood.
A wide range of antidepressants may be used to treat the disorder, but only one -- Eli Lilly and Company's Cymbalta -- has been specifically approved for the condition.
The FDA approval for use in fibromyalgia patients came last June, making it just the second drug approved to treat the disorder.
Pfizer's Lyrica was the first drug approved for fibromyalgia, but it was not included in the analysis because it is not an antidepressant. It is believed to work by targeting a key pain center within the brain.
Antidepressants vs. Fibromyalgia
Researchers examined 18 studies involving 1,427 fibromyalgia patients taking different classes of antidepressants, including low doses of tricyclic and tetracyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), serotonin and noradrenaline reuptake inhibitors (SNRI), and monoamine oxidase inhibitors (MAOIs).
Among the major findings:
- The TCA amitriptyline (Elavil, Endep), given in low doses, had the largest effect on pain, fatigue, and sleep disturbances. Little effect was recorded on depressed mood, however.
- The SNRIs Cymbalta and milnacipran, which is not yet approved for sale in the U.S., were found to have a small effect on pain, sleep disturbance, and depressed mood.
- The SSRI antidepressants Prozac and Paxil also had a small positive effect on pain and depressed mood, but no effect on fatigue and sleep.
- The MAOIs moclobemide (Aurox, Manerox) and pirlindole (Pyrazidol) had a modest effect on pain, but there was no evidence that moclobemide improved fatigue or sleeplessness.
Researcher Winfried Hauser, MD, of Germany's Saarbrucken Hospital, tells WebMD that the TCA amitriptyline and the SNRI Cymbalta are the antidepressants with the most evidence of effectiveness for the short-term treatment of fibromyalgia.
Lilly spokeswoman Sonja Popp-Stahly tells WebMD that the three company-funded Cymbalta studies included in the analysis show that the drug works in fibromyalgia patients with and without depression.
Since none of the studies in the analysis followed patients for longer than six months, the long-term effectiveness of these drugs is not clear, Hauser notes.
"Fibromyalgia is a lifelong disorder, so we definitely need to study these drugs to see if they work for long periods," he says.
Antidepressants Don't Work for All
And while antidepressants can improve fibromyalgia symptoms, they don't work for everyone.
According to Hauser, about one out of four to six patients experiences significant pain reductions of about 30% while taking an antidepressant.
Since antidepressants can have significant side effects, even when given in small doses, patients taking them for fibromyalgia should be followed closely, he adds.
Right now, it is not clear which fibromyalgia patients will benefit from treatment with antidepressants and which ones will not, but National Fibromyalgia Association President Lynne Matallana tells WebMD that this may soon change.
"These drugs are useful in a certain population of people with fibromyalgia," she says. "I would say that within three years we will be better able to tell who these patients are and target treatments to them."
University of North Carolina rheumatologist and professor of medicine Nortin Hadler, MD, remains unconvinced that fibromyalgia is a distinct medical condition and he says it is far from clear whether the benefits of giving antidepressants for this indication outweigh the risks.
Just over 75% of the patients taking antidepressants in the analysis reported side effects, compared to just over 62% of patients taking placebo.
"I have a problem with telling people to take antidepressants if they are not suffering from depression," he says. "In the studies included in the analysis, the patients who responded to treatment did not get that much better. There is nothing dramatic going on with these drugs except their side effects and their price."
Other Fibromyalgia Treatments
Matallana points out that while drug treatments have been shown to help some fibromyalgia patients, so have other approaches to treatment including:
- Diet and exercise. Studies suggest that more than half of fibromyalgia patients become obese, although the reason for this is not well understood. Eating a healthy diet may help, and studies have shown that regular exercise boosts endorphin production, which can decrease pain.
- Physical therapy. Physical therapy can help relieve fibromyalgia pain and stiffness and help relax tense muscles.
- Cognitive behavioral therapy, therapeutic massage, biofeedback, and other nontraditional approaches have been shown to help some patients.
"One of the most important and most challenging things is to find a health care provider who knows about fibromyalgia," she says. "That can be really difficult, because so many physicians still don't understand it."