As per the study published in “BioPsychoSocial Medicine”, mirtazapine was found to alleviate the gastrointestinal symptoms of patients with IBS-D. It was also found to improve the quality of life and psychological symptoms like anxiety. Investigators carried out this randomized double-blind placebo-controlled eight-week study to assess whether mirtazapine (5-HT3 receptor antagonist) is effective and safe to treat individuals suffering from IBS-D when compared to placebo.

The study recruited 67 subjects fulfilling Rome IV criteria for IBS-D. Participants were divided into either the mirtazapine arm (n = 34) or the placebo arm (n = 33). Individuals initiated 15 mg/day mirtazapine at bedtime for about 1 week. After this, the dose was elevated to 30 mg/day for an additional seven-week. The endpoints were alterations in (i) IBS Quality of Life, (ii) Hospital anxiety and depression scale score (HADS), and (iii) the total IBS symptom severity score (IBS-SSS).

Furthermore, alterations in the diary-based symptoms scores including pain, urgency and frequency of defecation, consistency of feces on 7-point Bristol Stool Form Scale, bloating, and the number of days per week with pain, bloating, diarrhea, or urgency, once during the one-week run-in period and last week of therapy were noted. All the assessments were carried on an intention-to-treat (ITT) assessment data set.

It was noted that in comparison with placebo, mirtazapine displayed superior efficacy to reduce the severity of the IBS symptoms. Moreover, at the end of the therapeutic period, all diary-derived symptoms except bloating displayed remarkably greater improvement in the mirtazapine-treated individuals vs. the placebo-treated individuals. Also, mirtazapine illustrated good tolerability and was found to considerably improve the individuals’ quality of life as well as anxiety.

Thus, mirtazapine appears to have promising advantages to treat individuals with IBS-D, specifically subjects having concomitant psychological symptoms.