Patients with chemotherapy-induced peripheral neuropathy may find pain relief in an anti-depressant, according to a new study published in the Journal of the American Medical Association.
Researchers at the University of Michigan School of Nursing say duloxetine, which is sold in the U.S by Eli Lilly (NYSE:LLY) under the brand name Cymbalta, shows promise in lessening the severity of pain that affects 20% to 40% of patients with cancer who receive neurotoxic chemotherapy.
“Painful chemotherapy-induced neuropathy can persist from months to years beyond chemotherapy completion, causing significant challenges for cancer survivors due to its negative influence on function and quality of life,” the authors wrote.
“Chemotherapy-induced peripheral neuropathy is difficult to manage, and most randomized controlled trials testing a variety of drugs with diverse mechanisms of action revealed no effective treatment.”
Usually caused by diabetes and rheumatoid arthritis, peripheral neuropathy is a nagging nerve pain characterized by a loss of feeling in the toes, feet, legs, hands and arms that often includes a persistent burning, tingling or prickling sensation.
Because anti-depressants have been effective in treating neuropathy-related pain in previous studies, Dr. Ellen M. Lavoie Smith and her colleagues conducted a randomized phase III trial to see if duloxetine would also lessen chemotherapy-induced peripheral neuropathic pain.
The study included 231 patients who were 25 years or older being treated at community and academic settings. Eligibility required that patients have a pain score of at least 4 on a scale of 0 to 10, representing average chemotherapy-induced pain. Patients were then randomized to receive either duloxetine followed by placebo or placebo followed by duloxetine.
The initial treatment consisted of taking one capsule daily of either 30 mg of duloxetine or placebo for the first week, and two capsules of either 30 mg of duloxetine or placebo daily for four additional weeks.
At the end of the initial treatment period, over half the patients (59%) in the duloxetine-first group reported a decrease in their pain, compared to 38% of those in the placebo-first group.
Quality-of-life also improved threefold for those treated with duloxetine during the initial treatment than for those treated with placebo. And 41% of the duloxetine patients reported a decrease in numbness and tingling in the feet versus 23% treated with placebo.
But the authors note that the effectiveness of duloxetine may be determined by the type of chemotherapy a patient is undergoing.
The results suggest that patients who received platinums (oxaliplatin) chemotherapy experienced as much as five times more benefit from duloxetine than those who received taxanes chemotherapy.
“In conclusion, five weeks of duloxetine treatment was associated with a statistically and clinically significant improvement in pain compared with placebo,” they wrote. “Exploratory analyses raise the possibility that duloxetine may work better for oxaliplatin-induced rather than taxane-induced painful chemotherapy-induced peripheral neuropathy.”
Duloxetine is used to treat major depression and anxiety, and has also been shown to relieve pain from diabetic neuropathy and fibromyalgia. The antidepressant appears to reduce pain by interrupting pain signals to the brain. Side effects include fatigue, nausea, insomnia and dizziness. In some studies, duloxetine has also been associated with suicide, most notably the case of a 19-year old woman who hanged herself in the bathroom of an Eli Lilly laboratory.