A 13 weeks randomized, double-blind and placebo parallel-controlled trial will be conducted to evaluate the clinical efficacy and safety of Zhizhu Kuanzhong Capsule in the treatment of functional dyspepsia-postprandial distress syndrome.

This is a multi-center, randomized, double-blind, placebo parallel-controlled International clinical trial of Zhizhu Kuanzhong Capsule in treating patients with Functional Dyspepsia-Postprandial Distress Syndrome (FD-PDS).

In this study, Hong Kong Baptist University will collaborate with Xiyuan Hospital of China Academy of Chinese Medical Sciences, and will be recruiting 60 FD-PDS patients as study subjects in Hong Kong, out of the total sample size of 480 patients.

The study includes a 1 week run-in period, 8 weeks double-blind treatment period and a 4 weeks of follow up period for each eligible subject. Eligible subjects will be randomly assigned to either the trial drug or the placebo.

6 follow-up visits and 1 telephone follow-up will be scheduled for each subject on the -7 days (visit 1), enrollment on day 0 (visit 2), 14th day (visit 3), 28th day (visit 4), 42nd day (visit 5, telephone follow-up), the 56th day (visit 6) and the 84th day (visit 7) respectively.

Urine, stool and blood samples will be collected from each subject on visit 2 and visit 6 for blood, urine, stool, liver and kidney function tests.

Inclusion Criteria:

1. Meeting the Rome IV diagnostic criteria for functional dyspepsia-postprandial distress syndrome;
2. At least 3 days during the one-week run-in period with VAS score ≥ 4 for major symptoms (at least one of postprandial fullness discomfort and early satiety) .
3. Be able to discontinue prohibited medications that may affect the evaluation of the effectiveness.
4. Written informed consent.

Exclusion Criteria:

1. Gastroscopic findings of gastric cancer, peptic ulcer, erosive gastritis (grade 2 or higher), moderate to severe atrophic gastritis, dysplasia, or other organ gastrointestinal disease.
2. History of abdominal surgery (except for appendectomy and cesarean section);
3. Immune system defects, or those who have been administered immunosuppressive agents or glucocorticoids within the past 3 months.
4. With combined severe cardiac and pulmonary insufficiency, insufficiency of liver (ALT/AST > 1.5 times the upper limit of the normal value), kidney insufficiency (BUN/SCr > the upper limit of the normal value), abnormal of endocrine system, abnormal hematopoietic system, and iron deficiency anemia as indicated on hematological examination.
5. With severe anxiety and depression.
6. With psychosis and mental retardation, language disorder precluding the ability of filling scales or recording symptoms.
7. Pregnancy or lactating; or patients of childbearing potential without effective contraception.
8. known to be allergic to the ingredients of this drug.
9. suspected or confirmed history of alcohol or drug abuse.
10. have participated in a clinical trial in the past 3 months.
11. deemed by the investigator as being not suitable for participation in the clinical trial.

The eligible subjects will be randomly assigned, with equal access to either the Chinese medicine treatment investigational drug group (Zhizhu Kuanzhong Capsule) or the placebo group.