Zhizhu Kuanzhong Capsule in treating patients with functional dyspepsia postprandial distress syndrome: study protocol for a multicenter, randomized, double-blind, placebo-controlled, parallel-group clinical trial

BACKGROUND: Functional dyspepsia (FD) is one of the most common functional gastrointestinal disorders. Based on the various symptoms present in patients with functional dyspepsia postprandial distress syndrome (FD-PDS), routine agents such as acid suppressants, prokinetic drugs, and centrally acting drugs, offer limited treatment choices with potential side effects. As a preliminary clinical trial showed that the marketed product Zhizhu Kuanzhong Capsule (ZZKZ) can improve symptoms in FD-PDS patients, our study aims to provide further evidence on the clinical efficacy and safety of ZZKZ in the treatment of patients with FD-PDS. METHODS: In this multicenter, randomized, patient- and investigator-blinded, placebo-controlled, parallel-group clinical trial, we will recruit patients with FD-PDS from 18 hospitals in China and Australia. The trial will enroll patients with FD-PDS based on the Rome IV diagnostic criteria. A total of 480 eligible patients will be randomized 1:1 into either ZZKZ or placebo group with 8 weeks of treatment and 4 weeks of follow-up. The primary endpoint will be measured by a self-rated Visual Analogue Score (VAS) for the degree of discomfort with both symptoms of postprandial fullness and early satiation, recorded once a day and 7 days a week. The primary analysis will aim to compare the response rate for FD-PDS VAS score between the groups before and after 8 weeks of treatment with an alpha level of 0.05 (2-sided). DISCUSSION: This trial aims to strengthen the evidence for the efficacy and safety of ZZKZ, a marketed product, in treating FD-PDS. Compared to the previous clinical trial that targeted FD-PDS, this trial will have an 8-week double-blind treatment period to investigate the effect of long-term mediation through comparison with the placebo group. TRIAL REGISTRATION: ClinicalTrials.gov NCT03825692. Registered on 28 January 2019 SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-022-06396-5.