The herbal preparation, STW5-II, reduces proximal gastric tone and stimulates antral pressures in healthy humans

Background: The herbal preparation, STW5-II, improves upper gastrointestinal symptoms, including abdominal fullness, early satiation, and epigastric pain, in patients with functional dyspepsia, and in preclinical models decreases fundic tone and increases antral contractility. The effects of STW5-II on esophago-gastric junction pressure, proximal gastric tone and antropyloroduodenal pressures, disturbances of which may contribute to symptoms associated with disorders of gut–brain interaction, including functional dyspepsia, in humans, have, hitherto, not been evaluated. 

Methods: STW5-II or placebo (matched for color, aroma, and alcohol content) were each administered orally, at the recommended dose (20 drops), to healthy male and female volunteers (age: 27 ± 1 years) in a double-blind, randomized fashion, on two separate occasions, separated by 3–7 days, to evaluate effects on (i) esophago-gastric junction pressures following a standardized meal using solid-state high-resolution manometry (part 1, n = 16), (ii) proximal gastric volume using a barostat (part 2, n = 16), and (iii) antropyloroduodenal pressures assessed by high-resolution manometry (part 3, n = 18), for 120 min (part 1) or 180 min (parts 2, 3). 

Key Results: STW5-II increased maximum intrabag volume (ml; STW5-II: 340 ± 38, placebo: 251 ± 30; p = 0.007) and intrabag volume between t = 120 and 180 min (p = 0.011), and the motility index of antral pressure waves between t = 60 and 120 min (p = 0.032), but had no effect on esophago-gastric junction, pyloric, or duodenal pressures. 

Conclusions & Inferences: STW5-II has marked region-specific effects on gastric motility in humans, which may contribute to its therapeutic efficacy in functional dyspepsia.