The Effect of Obeticholic Acid in Healthy Volunteers

Overview

This study investigates whether obeticholic acid affects gut microbiota, gastric motility, accommodation, and gastrointestinal peptide in healthy subjects. This study is a single-blind, placebo-controlled, randomized study. Twelve healthy volunteers will take one tablet containing obeticholic acid (10 mg) or a placebo once per day for 21 days for the first intervention. After 28 days washout period, they will take a tablet different from the one taken in the first intervention. Before the first intervention, they will receive MMC, IGP and endoscopy exam. At the end of the first and second interventions, they will receive the same exams. During MMC\&IGP, we will take blood samples to measure plasma hormones (motilin, octa-ghrelin, GLP-1, GLP-2, GIP, and insulin) and take duodenal fluid. When the endoscopy, we will take samples from the duodenal for microbiota, permeability measurement, RNA, protein, and pathology. Before and during the interventions, stool samples will be collected.

Functional dyspepsia (FD) is a common functional gastroduodenal disorder that has a great social and economic impact on patients. The pathophysiology of FD remains poorly understood and is most likely heterogeneous, but likely candidates are genetic factors, stress and duodenal luminal factors, including bile acids. Obeticholic acid (OCA), a Farnesoid X receptor (FXR) agonist, is an effective drug for primary biliary cirrhosis. Recently, it has been shown that OCA altered the gut microbiome via induction of lower endogenous bile acid levels in mice. OCA might alter the gut microbiota and duodenal inflammation. Moreover, gastric motility, accommodation and gastrointestinal peptide might be affected through the change in duodenal circumstances. Therefore, the aim of the current research protocol is to investigate the relationship between FXR agonist and gut microbiota, gastric motility, accommodation, and gastrointestinal peptide in healthy volunteers. During the screening of our healthy volunteers, the study will be explained, and the informed consent will be read together. When the volunteer agrees, it will be checked whether the volunteer is included, and some questionnaires will also be completed. A total of 20 healthy volunteers will be included and then randomized. All volunteers participate in both treatment arms: OCA or placebo. Participants will take each OCA and placebo for 21 days across the washout period at home. A motility test is performed before and at the end of each treatment. A high-resolution pressure gauge (HRM) catheter is placed into the proximal part of the small intestine (checked by fluoroscopy) and an intravenous catheter in the arm for blood sampling. The measurement in the fasted state will be performed until a characteristic cycle called as migrating motor complex cycle (MMC) is measured at least once. During migrating motor complex measurement, blood samples will be taken via a syringe that we connect to the line of your catheter every 20 min within the first 60min of MMC measurement, then every 10 min until the end of MMC phase III. Duodenal fluids are also aspirated and collected during the fasted state. From 30 minutes after the end of the MMC measurement, participants will start to drink a liquid nutrient meal at a constant speed while gastrointestinal motility continues to be monitored. In the meantime, a blood sample is taken every 10 minutes to measure hormones later. The measurement will finish 60 minutes after the start of the meal. During intragastric pressure measurement, participants must score their appetite feelings every 5 minutes on a scale questionnaire. An endoscopy is performed before and at the end of each treatment. Duodenal tissues (maximum 9) are collected using biopsy forceps via an endoscope. Participants will collect stool samples at home using the sampling material before taking the drug on day 1 and after taking the drug on days 2, 4, 7, 14, and 21.