Cymbalta (duloxetine) was approved by the U.S. Food and Drug Administration to treat fibromyalgia pain in 2008. This approval was granted based on the findings from several randomized, double-blind, placebo-controlled trials (the “gold standard” of research design for studies that seek to investigate the effectiveness of a particular treatment). The results of these studies offered the initial evidence to support the safety and effectiveness of Cymbalta as a treatment for fibromyalgia.
Arnold and colleagues in 2004, studied 207 fibromyalgia patients, all of whom met the American College of Rheumatology (ACR) criteria for fibromyalgia diagnosis. Patients were randomly assigned to receive either 60mg of Cymbalta or a placebo twice a day for 12 weeks. The study found that compared to those who received placebo, patients treated with Cymbalta experienced significant improvements in the severity of their pain, the number of their tender points, stiffness, and various quality of life measures (Arnold et al., 2004). Another study, published the following year by the same research group, also used a randomized, double-blind, placebo-controlled design to evaluate Cymbalta in 354 female fibromyalgia patients. Patients in this study received 60mg of Cymbalta once a day, 60mg Cymbalta twice per day, or a placebo over the course of 12 weeks. The findings from this study showed that those who were treated with Cymbalta at any dose showed greater improvements in pain severity and several quality of life measures than those patients who received placebo. Furthermore, approximately 50% of the patients in both Cymbalta treatment groups experienced at least a 30% improvement in their pain severity (compared to 33% in the placebo group). This study provided evident that Cymbalta at daily doses of either 60gm or 120mg is both safe and effective for the treatment of fibromyalgia-related pain (Arnold et al., 2005).
In 2008, Russell and colleagues performed another randomized-controlled trial in 520 fibromyalgia patients. This study evaluated Cymbalta disease of 20mg, 60mg, and 120mg versus placebo. Patients in each dose group took one daily dose over a six month period. et al. An interim analysis after three months of treatment, as well as the final analysis at six months, revealed that patients who received 60mg and 120mg of Cymbalta experienced greater improvements in the severity of their pain compared to those who received the 20mg dose or placebo (Russell et al., 2008).
Since receiving FDA approval, research has continued evaluate the use of Cymbalta in a number of domains related to fibromyalgia. Several newly published articles by prominent fibromyalgia research groups have confirmed the effectiveness of Cymbalta. Bennett et al. (2012) have provided additional evidence to show the effectiveness of Cymbalta at improving stiffness in fibromyalgia patients, and Arnold and colleagues recently published a paper that provides data to support a significant and positive impact of Cymbalta on fibromyalgia-related fatigue (Arnold et al., 2011). Additionally, Choy et al. (2011) suggest that Cymbalta, and other drugs in the selective norepinephrine reuptake inhibitor (SNRI) class of antidepressants, may be effective when used in a combined therapy approach with Lyrica (pregabalin) to treat fibromyalgia-related pain.
Other research has investigated the use of Cymbalta, as well as other fibromyalgia drugs, from a health systems and economic perspective. Gore et al. (2012) recently published an article that looked at the comorbid conditions, treatment patterns, and healthcare-related costs among fibromyalgia patients who had recently been prescribed either Cymbalta or Lyrica. The study found that those who were prescribed Cymbalta on average decreased their use of other SNRI medications as well as tricyclic antidepressants, however they tended to increase their use of anticonvulsant medications. For both groups of patients (i.e., those taking Cymbalta or Lyrica, significant increases in pharmacy and healthcare-related costs were observed following the start of therapy with either drug, as well as significant increases costs related to outpatient doctor visits. A recent analysis has also shown that Cymbalta is a cost-effective treatment approach for fibromyalgia when incorporated into standard therapeutic regimens (Beard et al., 2011). In addition, although limited by its use of retrospective administrative claims data, a study by Wu et al. (2011) found that patients who were prescribed Cymbalta doses of at least 60mg per day were much more compliant with their medication regimens than those who were prescribed 30mg/day or less. Interesting, this study also found that those patients who took. Healthcare-related cost differences were also observed between patients who took various daily doses.