Double-blind, randomized, 8-week multicenter study of the efficacy and safety of STW 5-II versus placebo in functional dyspepsia

Background and aim: Herbal products are widely used to treat patients with disorders of gut brain interaction but clinical efficacy and safety data for treatments lasting >4 weeks are widely lacking. We evaluated the efficacy and safety of 8 weeks of treatment with the herbal combination product STW 5-II for patients with functional dyspepsia (FD) meeting Rome II criteria. We also conducted a post hoc analysis including patients meeting Rome IV criteria for FD and evaluated the effect of the G-protein beta 3 (GNB3) subunit polymorphism (C825T) on therapeutic response.

Methods: This multicenter, placebo-controlled, double-blind study included 272 FD patients meeting Rome II criteria in the intention-to-treat cohort and 266 meeting Rome IV criteria. We used the validated Gastrointestinal Symptom Score (GIS) to assess GI symptoms, defining response rate as the proportion of patients with ≥50% GIS improvement in at least three of four assessments.

Results: After 8 weeks, the response rate was significantly higher in the STW 5-II group versus placebo (61.2% vs 45.1%, P = 0.008). Mean GIS non-significantly improved with STW 5-II treatment (7.9 ± 4.41 vs 6.7 ± 4.91 with placebo; P = 0.07). In the Rome IV subgroup analysis, STW 5-II yielded a better response rate (P = 0.01) versus placebo and greater postprandial distress symptom improvement (P = 0.04) versus placebo. Safety parameters did not differ between groups, and GNB3 status was not linked with therapeutic response.

Conclusion: STW 5-II is efficacious, with no observed safety signals at up to 8 weeks of treatment in patients with FD meeting Rome II or IV criteria.