A drug currently used to treat depression and fibromyalgia helps relieve neuropathic pain caused by chemotherapy, according to a new study. Researchers at the Universityof Michigan say the antidepressant drug duloxetine, sold commercially as Cymbalta, helped relieve painful tingling sensations in 59 percent of chemotherapy patients. It is the first clinical trial to find an effective treatment for that type of pain.
Chemotherapy-induced peripheral neuropathy is a common side effect of some chemotherapy drugs. Most patients only feel an unpleasant tingling — usually felt in the toes, feet and hands — but for about 30 percent of patients, it’s a painful sensation. Previous studies have found no reliable way to treat it.
The study, which is being presented at the annual meeting of the American Society of Clinical Oncology, looked at 231 patients who reported painful neuropathy after receiving the chemotherapy drugs oxaliplatin or paclitaxel. Patients were randomly assigned to receive either duloxetine or a placebo for five weeks. They were asked to report on their pain levels weekly.
The researchers found that 59 percent of patients who received duloxetine reported less pain, while 39 percent of those taking placebo did. Participants received a half dose of duloxetine – 30 milligrams a day – during the first week of the study before ramping up to a full dose of 60 mg for the remaining four weeks. Fewer side effects, such as fatigue, were reported with this approach.
“These drugs don’t work in everyone. The good news is it worked in the majority of patients. We need to figure out who are the responders. If we can predict who they are, we can target the treatment to the people it’s going to work for,” said lead author Ellen M. Lavoie Smith, PhD, assistant professor at the University of Michigan School of Nursing and a researcher at the U-M Comprehensive Cancer Center.
Treating pain from chemotherapy-induced peripheral neuropathy is critical to cancer treatment because the condition can lead doctors to limit the patient’s chemotherapy dose if the pain becomes too severe.
“In addition to improving symptoms and quality of life, treating peripheral neuropathy pain potentially improves quantity of life if it helps patients avoid decreasing their chemotherapy medications,” said Smith, who adds that patients often avoid telling their doctors about pain because they do not want their chemotherapy dose decreased.
“Patients make this trade-off sometimes: They don’t want to give up the chemotherapy and decide they’d rather have this pain. That’s a terrible trade off to make,” Smith says.
Duloxetine, which is manufactured and marketed by Eli Lilly, 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.
Funding for the UM study was provided by the National Institutes of Health’s National Cancer Institute. The researchers’ next steps are to determine which patients are likely to benefit from duloxetine.