About 20% to 40% of cancer patients receiving neurotoxic (nerve-damaging) chemotherapy develop a side effect known as peripheral neuropathy that leaves their fingers and toes, and often their hands and feet, numb or tingling. And this isn’t a good kind of tingling—for some, the sensation is so uncomfortable or painful that their chemotherapy dosage must be reduced. Unfortunately, the discomfort can last for months or years after chemotherapy ends.
No medication or other known treatment has succeeded at relieving the discomfort—until now. According to a new study, a drug that is already on the market can relieve chemotherapy-induced peripheral neuropathy. It is duloxetine, better known as the antidepressant Cymbalta. Though it can have side effects of its own, cancer patients who are really suffering from neuropathy will want to be aware of this new option.
MEASURING THE DIFFERENCE
For the new study, researchers decided to see whether duloxetine could help cancer patients with peripheral neuropathy because the drug had previously been shown to help diabetics who had a similar condition called diabetic neuropathy. Participants in the new study included 231 adult cancer patients who developed peripheral neuropathy after receiving neurotoxic chemotherapy.
Half of the participants took a placebo and the other half took duloxetine. Initially, the patients receiving duloxetine were given 30 mg per day, but after a week the dose was increased to 60 mg, which is a typical dose used to treat depression. In addition, each week for five weeks, all the study participants rated their pain severity on a scale from zero to 10.
Results: In the duloxetine group, 59% of patients reported a decrease in pain…in the placebo group, 38% reported a decrease in pain. The amount of the reduction was significant. At the start of the study, the average neuropathic pain score for patients receiving duloxetine was 6.1—and after five weeks of treatment, that score dropped by 1.06, on average. For placebo-treated patients, the baseline neuropathic pain score was 5.6—and that score dropped by an average of just 0.34 points after five weeks. (The study was not designed to determine whether patients experienced any mental health benefits from taking duloxetine, nor whether the neuropathic pain returned after patients went off the drug—more research is needed to answer those questions.)
HOW IT WORKS
Duloxetine is in a class of drugs knows as selective serotonin and norepinephrine reuptake inhibitors.These drugs work by upping the amounts of serotonin and norepinephrine, natural substances in the brain that interrupt pain signals to the brain.
Caveats: Not all chemotherapy drugs work the same way or have the same lasting effects on cancer patients’ systems. For instance, study participants who had received the chemotherapy drug oxaliplatin got somewhat better pain relief from duloxetine than participants who had received the chemo drug paclitaxel. With yet other chemotherapy drugs, the effects also could vary.
In addition, duloxetine has its own possible side effects, such as nausea, dry mouth, constipation and sleep difficulties, although these generally are mild and some typically subside within a few weeks. Adverse psychological side effects from duloxetine, though uncommon, are possible—these can include anxiety, anger, aggression and, rarely, thoughts of suicide. In the new study, no participants reported any severe physical or psychological side effects from taking the medication.
As with all drugs, there are certain interactions to be aware of. For instance, taking duloxetine with warfarin (the blood thinner) or NSAIDs (such as aspirin or ibuprofen) may increase bleeding risk.
Bottom line: If you are suffering from peripheral neuropathy after being on chemotherapy, consider asking your doctor whether duloxetine is worth a try.
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