Cymbalta (duloxetine) is more effective than Lyrica (pregabalin) for the treatment of chronic pain associated with fibromyalgia, but has a higher dropout rate due to adverse events, a study has found.
The study, “Comparing duloxetine and pregabalin for treatment of pain and depression in women with fibromyalgia: an open-label randomized clinical trial,” was published in the DARU Journal of Pharmaceutical Sciences.
Fibromyalgia is characterized by widespread chronic pain that is often accompanied by anxiety, depression, sleep disorders, and fatigue.
There are no specific therapies for this condition, so patients are often treated with medicines initially developed for other diseases.
Cymbalta, an antidepressant, and Lyrica, an anti-epileptic, are two of the most commonly prescribed medications for the treatment of fibromyalgia. Both have been approved by the U.S Food and Drug Administration and Health Canada.
Although the treatments have different modes of action, they are associated with a reduction in pain and depression as well as other mental symptoms.
A team of researchers in Iran designed an open-label clinical trial to compare the efficacy and side effects of both therapies.
They evaluated 99 fibromyalgia patients, between the ages of 18 and 65 years old, who were randomly assigned to take one of the therapies for four weeks. Patients had not received any of the medications for 12 weeks before the start of the study and had no other conditions that caused chronic pain.
A total of 35 patients in the Cymbalta arm and 31 patients in the Lyrica arm finished the four-week trial and were included in the final results.
The researchers compared the scores of the Widespread Pain Index (WPI) and Beck Depression Inventory-II of each patient before the start of the study and after four weeks of treatment, which were the primary objectives.
During the trial, both groups showed significant improvements in the scores of both indexes. However, patients taking Cymbalta had significantly better WPI scores than those taking Lyrica, whereas the Beck scores were similar in both groups.
“We hypothesized that [Cymbalta] is more effective on physical symptoms, in particular, pain, than [Lyrica], but similarly effective on mental health outcomes, such as depressive symptoms and mental health quality of life,” the researchers wrote.
However, more patients taking Cymbalta abandoned the study due to adverse events than patients taking Lyrica.
The Cymbalta group reported a higher incidence of nausea, and, to a lesser extent, constipation, dry mouth, headache, and insomnia. The Lyrica group had slightly more cases of dizziness, lightheadedness, and drowsiness. Most adverse events occurred during the first two weeks of the trial.
“We provided further evidence for higher efficacy of [Cymbalta] compared with [Lyrica] monotherapy to reduce pain in patients with fibromyalgia. Nevertheless, adverse events, adherence to treatment, and drug-drug interactions should be considered when deciding to tailor [Cymbalta] or [Lyrica] to an individual patient,” the authors concluded.
Further clinical trials that compare the effects of the medicines in the long term are necessary to validate these findings, according to the researchers.