Effect of Iberogast (STW5) on tolerance to colonic gas in patients with irritable bowel syndrome: A randomized, double-blind, placebo control clinical trial

BackgroundSTW5 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.AimTo determine the effects of STW5, compared to placebo, on the responses to colonic gas in IBS.MethodsUsing 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.ResultsColonic 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).ConclusionsSTW5 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. Using a double blind, cross-over, placebo controlled study design, STW-5 reduced abdominal symptoms induced by colonic gas filling in patients with IBS. The previously reported positive effects of STW-5 in patients with IBS could be related to an improved tolerance to colonic gas contents, by reducing sensitivity to colonic loads.image