Efficacy of otilonium bromide in irritable bowel syndrome: a pooled analysis

Otilonium bromide (OB) is a spasmolytic agent acting as an L-type calcium channel antagonist in intestinal and colonic smooth muscle cells (SMCs). We analyzed three independent clinical trials with homogeneous design on patients with irritable bowel syndrome (IBS). After 2 weeks receiving placebo, patients were randomized to receive OB (3 × 40 mg daily) or placebo for 15 weeks. We aimed to perform a pooled analysis of the data from these homogeneous clinical trials to evaluate the efficacy of OB treatment on symptoms and global response of patients.

A total of 883 patients with IBS (69.8% women, mean age 46.2 years, 43.8% mixed type) were included, 442 treated with OB and 441 with placebo. The efficacy results from the three studies at weeks 5, 10 and 15 were pooled in an intention-to-treat (ITT) strategy, analyzed with a logistic regression model and described by forest plots.

Despite a placebo effect in all efficacy variables, a significant therapeutic effect of OB was observed at weeks 10 and 15 with reference to: (a) intensity and frequency of abdominal pain; (b) rate of responders as evaluated by patients (71.8% at week 10 and 77.2% at week 15); (c) severity of bloating; (d) rate of responders as evaluated by physicians (55% at week 10 and 63.9% at week 15). No significant OB effect was observed in stool frequency and consistency.

OB is more effective than placebo in IBS treatment. Therapeutic benefits are significant after 10 weeks and are maximal after 15 weeks of treatment.