Elobixibat, an ileal bile acid transporter inhibitor, induces giant migrating contractions during natural defecation in conscious dogs

Background Chronic constipation affects 14%‐17% of the population. Elobixibat, a novel, ileal bile acid transporter (IBAT) inhibitor, has been approved as a new chronic constipation drug in Japan in January 2018. The present study aimed to examine the pharmacological effects of elobixibat on colonic motility in conscious dogs using a telemetry system. Methods Six male beagle dogs were surgically implanted with strain gauge force transducers for gastrointestinal (GI) motility recording. The motility index was calculated from GI motility at each recording site in conscious and nonrestraint dogs. The fasted dogs were orally administered elobixibat (3, 10, or 30 mg kg−1) or 30 mg kg−1 of sennoside as positive control or vehicle using a crossover design and washout period of more than 6 days. One hour after drug administration, the dogs were fed chow, and GI motility and defecation were observed for 10 hours; GI motility was quantified to calculate giant migrating contractions (GMCs). Fecal bile acids (BAs) were determined as well. Key Results Elobixibat and sennoside significantly increased the number of defecations, fecal wet weight, and water content within 10 hours after administration. Elobixibat dose‐dependently decreased the time to first bowel movement, increased the amount of total fecal BAs, and rapidly induced mild GMCs during defecation; however, higher strength of GMCs was observed with sennoside. Conclusions & Inference Elobixibat induces bowel movements faster than sennoside through a different mechanism. Elobixibat locally inhibits IBAT in the ileal lumen, leading to elevated fecal BAs in the colon and induced mild GMCs during defecation. No reports have investigated whether elobixibat directly enhances colonic motility. Elobixibat mildly induced giant migrating contractions (GMCs) during defecation in conscious dogs although higher GMCs were observed in the sennoside group.