The Safety and Efficacy of Ramosetron versus Psyllium for the Treatment of Fecal Incontinence (SERAFI): Study protocol for a randomized, parallel, non-inferiority trial

Background: Fecal incontinence (FI) is a prevalent condition affecting 2% to 21% of the general population, with higher rates in older adults and specific settings such as nursing homes and hospitals. Current treatments include supportive care, biofeedback, anal injections, and sacral nerve stimulation, though these can be invasive or costly. Pharmacological therapies, like stool bulking agents and constipating agents, help manage symptoms but can have side effects. Ramosetron, a 5-HT3 receptor antagonist, shows promise for FI treatment by reducing intestinal motility and improving stool consistency. This study aims to compare the effectiveness and safety of ramosetron (Irribow®) and psyllium (AGIO®) in treating FI in a randomized, parallel, non-inferiority trial. Methods: This study will include adults aged 19 years and above who are diagnosed with FI. Participants will be randomly assigned to receive either ramosetron (5 μg for males, 2.5 μg for females) or psyllium (6 g) once daily. The primary endpoint will compare changes in Fecal Incontinence Severity Index (FISI) scores before and after medication. Secondary endpoints will include comparisons of FISI scores, Fecal Incontinence Quality of Life (FIQL) scores, patient satisfaction surveys, and Bristol Stool Scale scores between the two groups. Follow-up visits will take place at baseline and at 1, 4, and 12 months to assess symptoms and administer surveys. The primary endpoint is the within-group improvement in FISI scores, while the secondary endpoint is a between-group non-inferiority comparison of ramosetron versus psyllium. A sample size of 56 participants is needed for statistical significance at the 0.05 level with 80% power, accounting for dropout, for a total of 148 participants. Discussion: It is believed that 5-HT3 receptor antagonists, along with Psyllium, can improve bowel habits and alleviate symptoms, thereby enhancing the quality of life for patients with FI. Trial registration: ClinicalTrials.gov NCT06166615, December 12, 2023. © The Author(s) 2025.