Patient description: A 34 year old man comes to the clinic complaining of dizziness and severe diarrhea since yesterday. He has returned from an international trip few days ago and was living in a camp in Sudan for a month. He developed abdominal pain followed by bloating and nausea as well as loose bowel movements. Soon he was having profuse watery diarrhea without odor. The stool is watery and white but the patient has no fever. Blood pressure is 95/62 lying down and drops to 75/40 standing. The skin turgor has reduced. HR is 110 and he looks ill with dry mucosa. V. cholerae was seen in dark-field microscopy of a fresh stool specimen. The lab study is as bellow: Sodium 137 meq/L Potassium 2 meq/L Chloride 94meq/L CO2 15 meq/L Fecal leukocytes None seen Fecal occult blood Negative

Clinical trial eligibility criteria: eligible ages (years): 18.0-65.0,  Irritable Bowel Syndrome With Constipation Male or female participants aged between 18 and 65 years inclusive Patient must be willing and able to participate in the study for the required duration, understand and sign the informed consent (ICF), and be willing to comply with all protocol-related visits and procedures Patient has had IBS-C symptoms (as defined by Rome III diagnostic criteria) for at least 6 months prior to diagnosis Patient has an average score of ≥ 3.0 for daily abdominal pain at its worst (11-point numerical rating scale [NRS]) during and up to the 17 days immediately before randomization (i.e. Pre-treatment Period) Patient has an average of ≤ 3 CSBMs per week or ≤ 5 SBMs per week during the 17 days immediately before randomization (i.e. Pre-treatment Period) Patient has a breath methane level ≥ 10 ppm on a lactulose breath test administered at Screening Patient may be on a stable, continuous regimen of fiber or probiotics one month before the Screening Visit; however, they must maintain a stable dose regimen through Week 12 Patient must agree to refrain from starting a new diet, changing stable dose of supplemental fiber, or changing exercise pattern that may affect IBS-C symptoms from the time of Screening through the end of the study. If the patient takes food products that are strong inhibitors of cytochrome P450 3A (CYP3A) (e.g. grapefruit juice, Seville orange juice, St. John's Wort), he/she must agree to refrain from taking these from the time of Screening through the end of the study Patient must agree to use an acceptable method of contraception from the time of signing the ICF to 30 days after the final dose of study drug if the patient is a sexually active female of child-bearing potential (defined as any female who has experienced menarche and who is NOT permanently sterile or postmenopausal. Postmenopausal is defined as 12 consecutive months with no menses without an alternative medical cause). Adequate contraceptive measures oral contraceptives (stable use for two or more cycles before Screening); intrauterine device; Depo-Provera®; Norplant® System implants; partner with a vasectomy; double-barrier birth control (e.g. use of a condom plus diaphragm or condom plus either contraceptive sponge, foam, or jelly); or abstinence. According to drug research standards, male patient must agree to use an acceptable method of contraception and refrain from donating sperm from the time of signing the ICF to 90 days after the final dose of study drug A female patient of child-bearing potential must be non-pregnant and non-lactating and have negative pregnancy tests at the Screening Visit and on Day 1 prior to dosing with study drug  Patient has loose (mushy) or watery stools for > 25% of their bowel movements (BMs) during the 12 weeks before Screening or during the Screening and Pre-treatment Periods Patient has a history of cathartic colon, laxative, or enema abuse Patient has a history of ischemic colitis Patient has a history of pelvic floor dysfunction Patient has a history of bariatric surgery for the treatment of obesity Patient has a history of surgery to remove a segment of the gastrointestinal (GI) tract at any time before the Screening Visit Patient has any history of myopathy, rhabdomyolysis, chronic myalgia, or familial history of hereditary muscular disorders Patient has been diagnosed with or has a family history of familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer, or any other form of familial colorectal cancer Patient currently has any structural abnormality of the GI tract or a disease or condition that can affect GI motility, or any unexplained and clinically significant symptoms such as lower GI bleeding, rectal bleeding, heme-positive stool, iron-deficiency anemia, weight loss, or systemic signs of infection Patient has had any previous surgery involving the abdomen, pelvis, or retroperitoneal region during the last 12 months prior to Screening, with the of laparoscopic gallbladder surgery or appendix removal