The FDA approved the serotonin and norepinephrine reuptake inhibitor duloxetine (Cymbalta) to manage peripheral neuropathic pain in people with diabetes. Duloxetine is a product of Eli Lilly and is also approved for the treatment of major depression in adults.
The safety and efficacy of duloxetine for treatment of peripheral neuropathy was demonstrated in two randomized, controlled clinical trials involving approximately 1,074 adults without depression who had the disorder for at least 6 months. Patients treated with duloxetine reported a greater decrease in pain compared with placebo. Of those treated with duloxetine, 58% reported at least a 30% reduction in pain; 34% of those given a placebo reported the same degree of pain reduction. Improvements were noted as early as the first week of treatment and continued for the duration of the studies. Duloxetine showed rapid onset of action and sustained effect in reducing pain at both dosages, and was effective at relieving pain at night.
The most common side effects associated with duloxetine are nausea, dry mouth, constipation, and diarrhea. Patients who have recently taken monoamine oxidase inhibitors, are taking thioridazine, or who have uncontrolled narrow-angle glaucoma should not take duloxetine.