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On February 26, 2007, the FDA approved Eli Lilly’s pain/sleep/mood drug duloxetine hydrochloride (Cymbalta^R) for treatment of generalized anxiety disorder - a condition that seems to affect Fibromyalgia patients more frequently than the general population. At the same time, Lilly announced that later in 2007, subsequent to phase III trials, it expects to ask the FDA to approve duloxetine for treatment of FM pain. (Even as phase II and III trials for treatment of CFS patients proceed in collaboration with the University of Cincinnati.)

Nevertheless, duloxetine is a very potent drug - like others in its class - with potentially serious adverse effects. Just what is it, and what benefits and risks might it represent for FM patients [and CFS patients] if approved?

A Widely Studied Drug
Duloxetine has now been studied in more than 25,000 patients worldwide, according to Lilly. It was previously FDA-approved for treating major depression and managing diabetic neuropathic pain.

How Does The Drug Work?
Duloxetine is a member of a class of drugs commonly referred to as serotonin and norepinephrine reuptake inhibitors (SNRIs). According to Lilly, “Serotonin and norepinephrine in the brain and spinal cord are believed to both mediate core mood symptoms and help regulate the perception of pain. Based on pre-clinical studies, duloxetine is a balanced and potent reuptake inhibitor of serotonin and norepinephrine that is believed to potentiate the activity of these chemicals in the central nervous system (brain and spinal cord).

“While the mechanism of action of duloxetine is not fully known, scientists believe its effects on depression and anxiety symptoms, as well as its effect on pain perception, may be due to increasing the activity of serotonin and norepinephrine in the central nervous system.”

Potential Benefits and Risks for Fibromyalgia Patients?
U.S. and Canadian trials of duloxetine in depressed and nondepressed Fibromyalgia patients have indicated that “while some effects of duloxetine on painful symptoms can be accounted for by its antidepressant action, the data strongly suggest that duloxetine also exerts a substantial direct analgesic effect over and above its antidepressant effects.” See the review, “Efficacy of duloxetine in painful symptoms: An analgesic or antidepressant effect?” and “Duloxetine Reduces Fibromyalgia Pain.”

Importantly, however, a recent review of trial reports in the French journal Prescrire advised physicians that duloxetine's efficacy for treating these two conditions has "not yet been demonstrated to be even equivalent to other available drugs, and has too many adverse effects, given this degree of uncertainty."

According to Wikipedia's discussion of the drug and its adverse effects, "Since duloxetine is a newer drug (FDA-approval 2004), not many peer-reviewed articles have been published on its adverse effects, and effect of long term use is still unknown. More than 40 different types of adverse effects have been reported, including completed suicide attempts and severe hepatic [liver] disorders." Also cited is a report in The Independent, a British newspaper, claiming that investigative reporters had "uncovered 41 deaths and 13 suicides for patients taking duloxetine as of June 19, 2005."

What Is Generalized Anxiety Disorder (GAD)?
GAD is a condition that affects more than 6.5 million Americans in any given year - and may occur more frequently in FM patients than the general population. (See "Does the high frequency of manic symptoms in Fibromyalgia influence the choice of treatment?" )

Symptoms persist for at least six months and can include exaggerated worry or chronic anxiety, irritability, poor concentration, sleep disturbance, and fatigue. The disorder may be brought on, or worsened by, stressful life events, and tends to be chronic with periods of exacerbation and remission.

In clinical trials, Lilly reports that on average, patients treated with Cymbalta^R for generalized anxiety disorder (also subject to the potential adverse effects discussed above) experienced a 46 percent improvement in anxiety symptoms, compared to 32 percent for those who took placebo, as measured by the Hamilton Anxiety Scale. In addition, patients in these studies experienced a 46 percent improvement in function, compared to 26 percent for those who took placebo as measured by the Sheehan Disability Scale.

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Note: This information has not been evaluated by the FDA. It is not intended to prevent, diagnose, treat, or cure any condition, illness, or disease. It is essential that you never make any change in your healthcare plan or regimen without first researching and discussing it in collaboration with your professional healthcare team.