Changyanning Tablet for the Treatment of Diarrhea-Predominant Irritable Bowel Syndrome (IBS-D)

Inclusion Criteria:

1. Meet IBS-D Rome IV diagnostic criteria;
2. Age between 18 and 65 years old (including boundary value), regardless of gender;
3. IBS symptom severity scale (IBS-SSS) scores > 175 points;
4. The weekly average score of abdominal pain in screening period is ≥ 3 points (The mostsevere abdominal pain in the past 24 hours every day, the pain score was 11 grades (0-10), NRS-11; Also the number of days of the stool character classification (Bristolstool scale) is type 6 or 7 ≥ 2 in a week;
5. Patients who voluntarily accept the program's plan of the project and signs theinformed consent form.

Exclusion Criteria:

1. Patients with serious or unstable heart, liver, kidney, immune, endocrine system andother diseases or malignant tumors;
2. Patients are affected by factors such as intellectual disorder, mental disorder andlanguage;
3. Patients with gastrointestinal organic diseases or with malignant tumors, such aspancreatitis, intestinal adenoma (excluding polypectomy for more than half a month),intestinal diverticulum, colon or rectal cancer, inflammatory bowel disease,intestinal tuberculosis, etc;
4. Other diseases (such as hyperthyroidism, diabetes, chronic renal insufficiency,nervous system diseases, etc.) that affect digestive tract dynamics;
5. Complicated with tuberculosis peritonitis, gallstones, cirrhosis, chronic pancreatitisand other gastrointestinal diseases;
6. Allergic constitution or allergic to the components of the studied drug;
7. Pregnant or lactating women, and women with recent fertility plans;
8. Previous abdominal or pelvic surgery, such as cholecystectomy;
9. Patients with positive fecal occult blood;
10. During the screening period, drugs that affect gastrointestinal motility and functioncannot be stopped, including parasympathetic inhibitors, such as scopolamine,atropine, belladonna, etc; Muscle relaxants, such as succinylcholine; Antidiarrhealagents such as loperamide, smecta, etc; Opioid preparations, etc;
11. Those who use probiotics (except those who eat yoghurt) or antibiotics within 8 weeksbefore enrollment in the study;
12. IBS drugs (except polyethylene glycol and loperamide) were used within 3 months beforethe study;
13. Those who regularly drink alcohol within 6 months before screening, i.e., drink morethan 14 units of alcohol every week (1 unit=360 mL beer or 45 mL liquor or 150 mL winewith 40% alcohol);
14. Those who have participated in or are currently participating in other clinical trialswithin 1 month before screening;
15. The researcher believes that there are patients who are not suitable for inclusion.