Rationale and design of a multicenter, single-group, open-label trial aiming at investigating the effectiveness of elobixibat for loss of defecation desire in patients with chronic constipation.

Background: Approximately 60% of patients with chronic constipation (CC) have a significantly higher rate of loss of defecation desire (LODD). Bile acids are expected to have a restorative effect on defecation desire (DD) because they lower the rectal sensory threshold, which is an objective index of DD. Elobixibat (EXB) specifically inhibits the ileal bile acid transporter/apical sodium-dependent bile acid transporter, which is a transporter involved in the reabsorption of bile acids in the terminal ileum. This study aims to investigate the LODD improvement rate in patients with CC after 4 weeks of EXB treatment. Methods: A total of 40 adult patients with CC who meet the eligibility criteria will be enrolled. Patients will receive oral EXB (10 mg/day) for 4 weeks. A patient diary will be provided daily at 4 weeks after treatment. The primary endpoint will be the percentage LODD improvement at week 4 of the treatment period from week 2 of the observation period using questionnaires. Ethics and dissemination: Ethical approval was obtained from the Yokohama City University Certified Institutional Review Board prior to participant enrolment (approval number: CRB21-008). The results of this study will be submitted for publication in international peer-reviewed journals, and key findings will be presented at international scientific conferences. Participants desiring the results of this study will be directly contacted for data dissemination. Trial registration: This trial was registered at ClinicalTrials.gov (NCT05165199). Protocol version: 1.0, September 21, 2021.

Rationale and design of a multicentre, 12-week, randomised, double-blind, placebo-controlled, parallel-group, investigator-initiated trial to investigate the efficacy and safety of elobixibat for chronic constipation.

INTRODUCTION: Chronic constipation (CC) is a functional disorder that negatively impacts the quality of life of patients. This is a protocol for a multicentre, 12-week, randomised, double-blind, placebo-controlled study to test the efficacy and safety of elobixibat (EXB) versus placebo in patients with CC. METHODS AND ANALYSIS: This will be a multicentre, double-blind, placebo-control, randomised controlled trial. A total of 100 adult patients with CC, diagnosed based on Rome IV criteria, who fulfil the inclusion/exclusion criteria will be enrolled. The patients will be randomly assigned to receive EXB (10 mg) or placebo treatment (n=50 per group). Blood tests and stool sampling will be performed 12 weeks following initiation of treatment and questionnaires will be issued to participants. The primary outcome will be the change in complete spontaneous bowel movements after 12 weeks of administration. The secondary outcomes will include the change in Japanese Patient Assessment of Constipation Quality of Life and absolute serum and faecal bile acid. ETHICS AND DISSEMINATION: Ethics approval has been obtained from Yokohama City University Certified Institutional Review Board before participant enrolment. The results of this study will be submitted for publication in international peer-reviewed journals and the key findings will be presented at international scientific conferences. PROTOCOL VERSION: V.3.0, 15 June 2021. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov (number NCT04784780).