The antidepressant mirtazapine appears to be a safe and effective treatment option for patients with fibromyalgia, according to a systematic review published in Rheumatology International.
Mirtazapine is a central alpha-2 antagonist currently FDA-approved for the treatment of major depressive disorder. It is a potent antagonist of 5-HT2 and 5-HT3 serotonin receptors, as well as H1 histamine receptors. “A key difference when compared to other treatment options is that mirtazapine targets many of the symptoms of fibromyalgia with its mechanism of action and simple once daily dosing,” explained the authors.
To investigate the role of mirtazapine for fibromyalgia, researchers searched various database and identified 3 randomized, placebo-controlled studies and 1 open-label trial that fit the inclusion criteria. The selected studies lasted 6 to 13 weeks in duration, included mirtazapine doses ranging from 15 to 30mg daily, and evaluated improvements in pain, sleep, and quality of life.
With regard to pain, 2 studies reported a significant improvement when compared to baseline, while 2 other studies found a significant improvement vs placebo. Although the studies used different pain assessment scales, a consistency in efficacy was observed despite the pain scoring system. Two of the trials included patients who were treatment-naive, while the other 2 included treatment-experienced patients who failed previous fibromyalgia therapies.
In the 2 studies that evaluated quality of life, a significant improvement in emotional role functioning and bodily pain was seen in fibromyalgia patients treated with mirtazapine vs placebo. Significant improvements in other domains (eg, general health, mental health, physical functioning, vitality) were also observed.
Significant improvement in sleep quality was observed among mirtazapine-treated patients in 2 studies. In one of these trials, a greater number of patients were classified as insomnia responders in the mirtazapine-treated group vs the placebo arm (Yeephu et al.). Another study showed a significant improvement in fatigue symptoms in 50% of mirtazapine-treated patients while 73% experienced improvement in sleep disturbances (Samborski et al.).
The most common adverse effects associated with mirtazapine use were dry mouth, increased appetite, somnolence, sleepiness, hypotension, weight gain, and nasopharyngitis.
Based on the study results the authors concluded that “mirtazapine at a dose of 15–30mg daily appears to be an effective and safe treatment option to improve pain, sleep, and quality of life in patients with fibromyalgia.” The clinical benefits were seen in both treatment-naive patients and those who failed prior fibromyalgia therapies.
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