Bangpungtongsung-san for patients with major depressive disorder: study protocol for a randomized controlled phase II clinical trial

BACKGROUND: Bangpungtongsung-san (BTS) is a representative herbal medicine that has been widely used for patients with obesity in east Asian countries. Various preclinical studies have demonstrated the anti-depressive effect of BTS granules in various animal models of depression. This phase II trial aimed to explore the efficacy and safety of BTS in human patients with depression. METHODS: A total of 126 patients diagnosed with major depressive disorder and who are not underweight (body mass index ≥ 18.5 kg/m(2)) will be enrolled in this study. Eligible participants will be randomly allocated into three groups: the high-dose BTS, low-dose BTS, and placebo groups in a 1:1:1 ratio. BTS or placebo granules will be orally administered twice a day for 8 weeks. The BTS and placebo granules will be made to have identical color, scent, and shape, and participants and investigators will be blinded to the allocation. The primary efficacy endpoint is the change from baseline of the 17-item Hamilton Depression Rating Scale total score at 8 weeks. The superiority of the high- and low-dose BTS granules to the placebo granules will be tested. DISCUSSION: The results of this clinical trial will provide evidence on the efficacy and safety of BTS for patients with major depressive disorder. This study will be conducted in accordance with ethical and regulatory guidelines, and the results will be submitted and published in international peer-reviewed journals. TRIAL REGISTRATION: CRIS registration Number: KCT0007571; registered on 2022/07/26 (https://cris.nih.go.kr/cris/search/detailSearch.do/23192). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12906-023-03912-1.