Effect of Iberogast (STW5) on Tolerance to Colonic Gas in Patients with Irritable Bowel Syndrome: A Randomized, Double-Blind, Placebo Control Clinical Trial

Abstract

Background: STW5 is an herbal medicinal product that, in previous studies, reduced abdominal pain in irritable bowel syndrome (IBS). The effect of STW5 on gas‐related abdominal symptoms is unknown. Aim: To determine the effects of STW5, compared to placebo, on the responses to colonic gas in IBS. Methods: Using a cross‐over design, two gas challenge tests were performed in 10 patients with IBS and bloating after 2‐weeks treatment with (a) STW5 and (b) placebo. The challenge test consisted in continuous infusion of gas into the colon (24 mL/min for 60 min), followed by a 30‐min free evacuation period. Gas evacuation, symptom perception, and abdominal distension were continuously registered. Results: Colonic gas filling was associated to a significant rise in abdominal symptom perception, that was significantly greater when patients were on‐placebo (score increment 4.0 ± 0.3) compared with on‐STW5 (score increment 3.2 ± 0.4; p = 0.035). Gas filling was associated to a progressive abdominal distension that was similar with both treatments. Opening of the rectal cannula produced a massive gas evacuation, similar after both treatments, associated to a return of abdominal perception and distension to basal levels when patients were on‐STW5 (score increment −0.1 ± 0.4; distension 0.3 ± 0.2 cm; p = 0.399, and p = 0.112 vs. basal), whereas both remained increased on‐placebo (score increment 0.5 ± 0.3; distension 0.8 ± 0.3 cm; p = 0.048, and p = 0.016 vs. infusion start). Conclusions: STW5 improves colonic gas tolerance in IBS patients with bloating without a significant effect on gas retention and evacuation. This medicinal product can be beneficious for treatment of gas‐related abdominal symptoms in patients with bloating. EudraCT: 2019‐003976‐38.