Duloxetine benefits women with fibromyalgia: men on duloxetine fared worse on the Fibromyalgia Impact Questionnaire total score than men on placebo.
Duloxetine's efficacy also appears to be independent of the presence of depression, according to findings from a randomized, double-blind, placebo-control trial involving 207 patients with and without major depressive disorder.
Dr. Arnold, director of the Women's Health Research Program at the University of Cincinnati, presented her findings at a symposium sponsored by Eli Lilly and Co. and Boehringer Ingelheim Pharmaceuticals, the two companies that jointly market duloxetine.
Overall, patients with and without major depressive disorder experienced significantly greater pain reduction with duloxetine than did those on placebo, and the differences between those with and without depression were almost nonexistent.
The striking difference in duloxetine's efficacy between men and women is puzzling, Dr. Arnold admitted, but it's important to note that most of the study participants were female (180, or 87%).
Women on duloxetine scored significantly better compared with those taking placebo on both on the Fibromyalgia Impact Questionnaire (FIQ) total score and on the FIQ pain score.
But men on duloxetine fared worse on the FIQ total score than those taking placebo. And FIQ pain scores were significantly better in men taking placebo than in those taking duloxetine.
Even so, because the cohort of men was so small, duloxetine was still found to be significantly effective overall, she noted. With the male patient data included, scores on the SF-36 were significantly better for the duloxetine group than the placebo group in physical subscore, bodily pain, general health perception, mental health, physical functioning, and vitality.
Patients enrolled in the 12-week trial all had been previously diagnosed with fibromyalgia. After a 1-week placebo lead-in period, the duloxetine group received doses that were titrated in the first 2 weeks, from 20 mg once daily to 60 mg twice daily.
Patients taking duloxetine had significantly higher rates of insomnia, dry mouth, and constipation than did those on placebo. In the placebo group, there were more cases of anxiety. None of these adverse affects were associated with significantly higher rates of discontinuation.
As for other treatment options, Dr. Arnold noted that in a related and similarly designed study involving 60 patients, she and her colleagues found that fluoxetine was significantly better than placebo in improving total FIQ scores and several other pain measures.
An open-label pilot study of venlafaxine also indicated that patients experience significant improvement, she said.
And in the pipeline is milnacipran, a serotonin and noradrenaline reuptake inhibitor that recently was shown in a phase II study to significantly improve multiple symptoms of fibromyalgia and to be well tolerated, Dr. Arnold said.
BY STEVE PERLSTEIN