Effect of Tenapanor on the Metagenomics and Metabolomics of Patients With Irritable Bowel Syndrome With Constipation

Inclusion Criteria: Ages 18-75 years old BMI >18.5 and <35 kg/m2 Rome IV criteria for IBS-C for at least 6 months Compliant with baseline stool submission prior to initiation of medication Ability to follow verbal and written instructions Ability to record daily bowel habits, including frequency, stool consistency (BSFS), and symptom severity Willingness to avoid major dietary changes and use of probiotics during the study period Informed consent form signed by the subjects Exclusion Criteria: History of loose stools History of irritable bowel syndrome with diarrhea (IBS-D) or mixed irritable bowel syndrome (IBS-M) Non-compliance with baseline stool submission Previous use of tenapanor GI motility obstruction or GI tract structural abnormality Current use of prescribed or illicit opioids History of pelvic floor dysfunction Need for manual maneuvers in order to achieve a BM History of GI lumen surgery at any time or other GI or abdominal operations within 60 days prior to entry into the study History of high-dose stimulative or cathartic laxative abuse as judged by investigator team Severe IBS-C as judged by the investigator Neurological disorders, metabolic disorders, or other significant disease that would impair their ability to participate in the study Cardiovascular disease, diabetes, cancer, Crohn's disease, ulcerative colitis BMI of <18.5 or >35 kg/m2 Pregnancy (or positive serum or urine pregnancy test(s) in females of childbearing potential) or lactation Absence of contraception in females of childbearing potential History of allergic reaction to tenapanor Administration of other FDA-approved agents for the treatment of IBS-C within 1 month prior to Screening Visit: Linaclotide Lubiprostone Plecanatide If treated with any of the following medications, dosing (or approximate frequency of 'as needed' use) must be stable for at least 30 days prior to Screening Visit and the subject must agree to maintain the same dose (or approximate frequency of 'as needed' use) or a decreased dose of medication throughout the study: Probiotics Bulk laxatives, fiber, and stool softeners Exclusion of colonic inertia with symptoms of < 1 BM per 2 weeks Subjects anticipating surgical intervention during the study Known history of diabetes (type 1 or 2) Subjects with recent antibiotic use (last 3 months) or anticipated antibiotic use during the study period History of inflammatory bowel disease Supine SBP > 160 mm Hg and/or supine DBP > 95 mm Hg (mean of two consecutive readings) Angina, coronary bypass, or myocardial infarction within 6 months prior to Screening Visit History of swallowing disorders History of gastric bypass or any other gastric surgery History of small bowel resection (except if related to appendectomy) History of gastric or duodenal ulcer History of gastroparesis History of abdominal radiation treatment History of pancreatitis History of intestinal stricture (e.g., Crohn's disease) History of intestinal obstruction or subjects at high risk of intestinal obstruction including suspected small bowel adhesions History of malabsorption History of hepatitis B or C History of human immunodeficiency virus History of cancer within the past 5 years (except adequately-treated localized basal cell skin cancer or in situ uterine cervical cancer) Any other clinically significant disease interfering with the assessments of tenapanor, according to the Investigator (e.g., disease requiring corrective treatment, potentially leading to study discontinuation) HbA1c > 8.5% (> 69 mmol/mol) 43. Any relevant biochemical abnormality interfering with the assessments of tenapanor, according to the Investigator 44. Antidiabetic medications within 1 month prior to Screening Visit (except stable dose of metformin, ≤ 1500 mg/day, for at least 1 month in subjects with type 2 diabetes) 45. Medications requiring mandatory administration twice per day with meals