Duloxetine approved to treat diabetic peripheral neuropathy.(Clinical Rounds)

After a 6-month priority review, the Food and Drug Administration last month approved duloxetine for managing pain associated with diabetic peripheral neuropathy, a symptom of nerve damage that affects up to 5 million Americans with diabetes.

The development marks the first time a drug has been specifically approved for this indication. Duloxetine (Cymbalta) is a balanced potent inhibitor of serotonin and norepinephrine reuptake manufactured by Eli Lilly & Co. The FDA approved duloxetine in August as a treatment for major depression in adults.

In an interview, Dr. Russell K. Portenoy, chairman of the department of pain medicine and palliative care at Beth Israel Medical Center, New York, called duloxetine's approval "significant because diabetic painful polyneuropathy is a very prevalent, distressing, and challenging pain syndrome."

"But it's also significant because drugs that are useful for painful diabetic polyneuropathy will most likely be adopted [in the treatment of] neuropathic pains more generally. As a group, these syndromes are in need of advances in therapy," said Dr. Portenoy, who is not affiliated with Eli Lilly or any clinical trials of the drug.

Duloxetine's approval followed two randomized, 12-week, double-blind, placebo-controlled, fixed-dose studies in more than 1,000 nondepressed adults who had diabetic peripheral neuropathy for at least 6 months. Patients received doses of either 60 mg or 120 mg per day. On average, patients in the studies were aged 60 years, had diabetes for about 11 years, and had diabetic neuropathy for about 4 years.

Of patients treated with duloxetine in the two studies, 58% reported at least a 30% sustained reduction in pain. Only 34% of patients who took the placebo reported this degree of sustained pain reduction.

Dr. Amy S. Chappell, a neurologist at Eli Lilly's headquarters who helped conduct the trials, noted that although both doses were safe and effective in patients who participated in the studies, the 120-mg dose was not as well tolerated as the recommended dose of 60 mg per day.