Randomized clinical trial: the effects of mirtazapine in functional dyspepsia patients

Background: Functional dyspepsia (FD) is one of the most common gastrointestinal disorders worldwide. Currently, anti-gastric drugs, gastric acid inhibitors, prokinetic drugs, and mucosal protective drugs are widely used in FD patients, however, only a small proportion of patients benefit from these drugs. Studies reported mirtazapine may improve symptoms of FD patients but the efficacy and safety of mirtazapine in the treatment of FD is unclear. Objectives: To investigate the efficacy and safety of mirtazapine in FD patients. Design: We performed a prospective, single-randomized, two-group parallel clinical trial involving 120 FD patients with poor traditional drug treatment outcomes to evaluate the efficacy and safety of mirtazapine. Methods: Qualified patients identified through the screening assessments were randomly divided into two groups: mirtazapine group (n = 60) treated with mirtazapine 15 mg qn on top of traditional drugs, and control group (n = 60) who continued to be treated with traditional drugs. Subjects were evaluated for meal-related symptoms and severity, quality of life, gastrointestinal-specific anxiety, and body weight before and after the 8-week intervention. Adverse reactions were also recorded. Results: At the end of 8-week treatment, dyspeptic symptoms in the mirtazapine group were significantly relieved compared with the baseline (7.95 +/- 1.86 vs 11.17 +/- 2.14, p < 0.001). Assessment of the impact of dyspepsia on patients' quality of life from the short form-Nepean Dyspepsia Index showed that patients generally feel better in mirtazapine group than control group (24.52 +/- 2.87 vs 28.64 +/- 4.32, p < 0.001). Mirtazapine group also showed significant weight gain and decreased visceral sensitivity index score. Conclusion: Compared with control group, 8-week administration of mirtazapine significantly improved the overall severity of symptoms of dyspepsia (such as individual symptoms of postprandial fullness, early satiation, nausea, and vomiting), gastrointestinal-specific anxiety, quality of life, and increased weight in FD patients. This study provided clues to clinicians that mirtazapine may be a good choice for the treatment of FD patients. Trial registration: This study was registered in the Chinese clinical trial registry (https://www.chictr.org.cn/index.html, protocol No. ChiCTR2100048304).