Cymbalta® was the first treatment approved by the FDA for the management of diabetic peripheral neuropathic pain (DPNP) and this was the first study to show these effects. Patients who suffer from chronic painful conditions such as painful diabetic neuropathy experience significant detriments to their quality of life.

“Patients with diabetes often have complications involving their nerves, eyes, and kidneys, which are caused, at least in part, by high levels of sugar in the blood over long periods.”

Existing treatments are insufficient—none of them are completely effective, and they all are burdened by side effects. Because of this, there is great interest in novel therapies such as Cymbalta® (duloxetine HCl), that have the potential to offer new benefits.

The described study was state-of-the-art for examining the efficacy of dual (norepinephrine and serotonin) reuptake inhibitor (SNRI) therapy in the treatment of diabetic neuropathy. Duloxetine is a novel, selective SNRI. Its use in this study served as a probe, and was the first conclusive evidence for effectiveness of this mode of action in DPNP. While duloxetine is approved for major depressive disorder, patients in this trial were non-depressed, providing evidence that the SNRI mechanism of duloxetine works independently in pain and depression.

Patients with diabetes often have complications involving their nerves, eyes, and kidneys, which are caused, at least in part, by high levels of sugar in the blood over long periods. When the nerves are damaged ("neuropathy") patients can experience numbness, tingling, and/or pain. This pain most often begins in the feet and/or hands ("peripheral").

In this study, Cymbalta® (duloxetine) reduced this kind of pain in patients who took it at 60 or 120 mg/day. The effect began in the first week, and continued throughout the duration of the 12-week study so it may last longer. On average, patients had about a 50% improvement in their pain, but some had more and some had less.

Duloxetine is not effective for the numbness or tingling, nor is it effective for the other complications of diabetes. It does not treat the underlying nerve damage, but can help reduce the pain. Duloxetine is the first FDA-approved treatment for DPNP. It is also approved to treat major depressive disorder (MDD). It is believed to work on both disorders by enhancing the effectiveness of two chemicals, serotonin and norepinephrine, which are involved in regulation of emotion and pain in the brain.

This work was instrumental in obtaining approval for marketing Cymbalta® for treatment of painful diabetic neuropathy. As a consequence, thousands of patients who have not had sufficient relief with, or were unable to tolerate alternative treatments, have the opportunity to use this novel therapy.