A Comparison of the Effects of ORP-101 Versus Placebo in Adult Patients With Irritable Bowel Syndrome With Diarrhea (IBS-D)

Inclusion Criteria: * Willing and able to comply with protocol, including completion of electronic daily diary as required. * Has a diagnosis of IBS-D (Irritable Bowel Syndrome with Diarrhea) and meets the Rome IV Criteria, by history, for both IBS and IBS-D. * Has abdominal pain intensity score, and stool consistency as determined by protocol and assessed by Investigator for the week prior to randomization. * Has not used loperamide within the 14 days prior to randomization. * Is on a stable diet for the past 12 weeks and is not planning to change lifestyle and/or diet during study. Exclusion Criteria: * History of clinically relevant pancreatic conditions including pancreatitis, pancreas divisum, or Sphincter of Oddi (SO) dysfunction with pancreatic manifestations. * History of biliary pathology including acute cholecystitis within 6 months or biliary pain including post-cholecystectomy pain. * Patients who have had biliary sphincterotomy with post-procedure persistent abnormal liver function transaminases (LFTs). * Planned elective surgery within the next 4 months. * Significant and/or severe medical illnesses such as cardiovascular, neurological, infectious, renal, hepatic or respiratory disorders that would interfere with the patient's medical care, participation in, or conduct of the study. * History of intestinal obstruction, stricture, toxic megacolon, GI (gastro-intestinal) perforation, fecal impaction, gastric banding, bariatric surgery, adhesions, ischemic colitis, or impaired intestinal circulation (e.g. aorto-iliac disease). * History of lactose intolerance uncontrolled on a lactose-free diet, or other malabsorption syndromes (e.g. fructose malabsorption). * Dysphagia or difficulty swallowing pills. * History of inflammatory bowel disease, celiac disease, Clostridium difficile colitis or have had recent unexplained GI bleeding within 3 months prior to screening. * History of major gastric, hepatic, pancreatic or intestinal surgery (appendectomy, hemorrhoidectomy, or polypectomy allowed as long as occurred \> 3 months prior to trial screening; uncomplicated laparoscopic or open cholecystectomy is allowed if no history of post-operative biliary tract pain and surgery occurred \> 3 months prior to screening). * Patients \>40 years of age at high risk for colon cancer must have had a screening colonoscopy within the past 3 years prior to trial screening visit or \> 50 years of age, must have had a normal screening colonoscopy within the past 10 years prior to trial screening visit. Patients with Lynch Syndrome or Familial Polyposis are excluded from the study. Other protocol-defined inclusion/exclusion criteria may apply.