Originally published by 2 Minute Medicine^® (view original article). Reused on AccessMedicine with permission.

1. Low-dose amitriptyline was associated with a marked decrease in IBS-SSS score at 6 months compared to placebo.

2. There were 5 serious adverse reactions (2 in the amitriptyline group and 3 in the placebo group).

Evidence Rating Level: 1 (Excellent)

Study Rundown:

Irritable bowel syndrome (IBS) is a functional disorder that is managed through dietary changes and lifestyle modifications. When first-line therapies fail, low-dose tricyclic antidepressants are suggested, as per the UK guideline; although, their clinical efficacy remains unclear. This randomized controlled trial aimed to assess the efficacy of low-dose oral amitriptyline as a second-line treatment for IBS. The primary outcome was IBS Severity Scoring System (IBS-SSS) score at 6 months, while key secondary outcomes were safety analyses. According to study results, low-dose amitriptyline was effective and well-tolerated as a second-line treatment for the treatment of IBS symptoms in the primary care setting. This study was strengthened by a randomized design with a large sample size and adequate long-term follow-up.

Click to read the study in The Lancet

Relevant Reading: Rifaximin Therapy for Patients with Irritable Bowel Syndrome without Constipation

In-depth [randomized-controlled trial]:

Between Oct 18, 2019, and Apr 11, 2022, 1253 patients were screened for eligibility across 55 general practices in England. Included were patients ≥ 18 years old with Rome IV IBS, and symptomatic despite dietary changes and first-line therapies. Altogether, 463 patients (232 to low-dose amitriptyline and 231 to placebo) were included in the final analysis. The primary outcome of IBS-SSS score at 6 months showed significant improvement with low-dose amitriptyline compared to placebo (-27.0, 95% confidence interval [CI] -46.9 to -7.10, p=0.0079). The secondary outcome of safety analyses revealed a low discontinuation rate for amitriptyline (20%) versus placebo (26%). Overall, findings from this study suggest that low-dose amitriptyline is a safe and effective treatment option for patients with IBS unresponsive to first-line therapies.

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