In a recent single-center, randomized, placebo-controlled clinical trial, it was observed that in dyspeptic patients, administration of STW5 (Iberogast) led to a decrease in reflux symptoms along with alleviating esophageal hypersensitivity. A total of 18 patients (seven men, median age 54, range [19-76]) were enrolled in this study to seek the impact of Iberogast on both esophageal sensitivity and motility, aiming to discern its role in decreasing the incidence and perception of reflux events.

Participants with a dyspepsia history, as per the Rome IV criteria, and presenting symptoms of heartburn were enrolled in this crossover trial. The allocation of patients was conducted randomly in a double-blind manner, maintaining a 1:1 ratio. One set of patients underwent a 4-week treatment phase with STW5 (20 drops administered thrice daily), followed by a subsequent 4-week period during which they received a placebo. In the alternate study group, patients commenced with a 4-week placebo phase, followed by a subsequent 4-week treatment period with STW5.

At the end of the 4-week therapy phase, subjects received an esophageal acid perfusion test to evaluate their sensitivity to acid. Subsequently, patients were given a portable pH-impedance recording apparatus before departing for their residences. Over the subsequent 24 hours, the device monitored acid exposure time and gastroesophageal reflux events. Evaluation of signs of dyspepsia and reflux was conducted through the utilization of the short form nepean dyspepsia index questionnaire (SF-NDI) and the reflux disease questionnaire (RDQ).

The key outcome focused on the overall RDQ score. The secondary endpoints encompassed motility parameters and esophageal sensitivity, RDQ sub scores, acid exposure recorded during the 24-hour pH-impedance study, reflux events number, and scores related to dyspeptic symptoms. There was no statistically significant difference in the primary outcome, with the total RDQ score being 2.33 (range: 0.25-4.33) compared to 2.67 (range: 1.17-4.00) for STW5 and placebo, respectively (P = 0.347). However, the subscale scores for "gastroesophageal reflux disease [GERD]" and "regurgitation" were lower following STW5 treatment than with the placebo (P = 0.049 and P = 0.007, respectively).

No statistical variations were observed in the acid exposure time and its sensitivity score along with reflux events between STW5 and placebo. In the subgroup examination of patients with established GERD confirmed by pH monitoring, STW5 notably decreased the overall count of acidic reflux occurrences (P = 0.028). Additionally, among individuals with reflux esophagitis, there was an extension in the median lag time to perception of acid following treatment with STW5 (P = 0.042).

These observations indicate a favorable impact of Iberogast on reflux symptoms in dyspeptic individuals, with a potential decrease in esophageal hypersensitivity as an underlying mechanism.