Clinical trial: renzapride therapy for constipation-predominant irritable bowel syndrome – multicentre, randomized, placebo-controlled, double-blind study in primary healthcare setting

ABSTRACT

Background Relatively few pharmacological treatment options are available for treating patients with irritable bowel syndrome. New and effective medicines are urgently required.

Aim To identify an appropriate dosage of renzapride (a 5-HT₄ receptor full agonist/5-HT₃ receptor antagonist) to treat abdominal pain/discomfort in patients with constipation-predominant irritable bowel syndrome.

Methods In this randomized, placebo-controlled, phase IIb study in the primary care setting, men and women were randomized to placebo or renzapride (1, 2 or 4 mg/day) for 12 weeks. The primary outcome measure was patient self-assessed relief of abdominal pain/discomfort during weeks 5–12. Secondary efficacy measures included patients' assessment of their bowel habits, stool consistency and quality of life.

Results Although there were no statistically significant differences between renzapride and placebo for relief from abdominal pain/discomfort, responder rates in the renzapride treatment groups increased dose dependently, with the 4 mg/day group being consistently numerically greater than placebo. Importantly, a larger numerical treatment difference vs. placebo was observed in women (8% and 12% respectively). Statistically significant improvements in bowel movement frequency and stool consistency were observed in the 4 mg/day group relative to placebo. Renzapride was well tolerated at all doses.

Conclusions This study confirms the gastrointestinal prokinetic effects of renzparide. The data also suggested a potentially beneficial effect on abdominal pain/discomfort in women with constipation-predominant irritable bowel syndrome.