Comparison of Rimegepant and Placebo for Pain in IBS

Irritable bowel syndrome (IBS) and, particularly, the pain component of IBS lack effective treatments. Antispasmodics, antidepressants and hypnotherapy have all been proposed for the treatment of pain. Their effectiveness in clinical practice is disappointing, despite meta-analyses suggesting efficacy. The study hypotheses are: that rimegepant will be safe, well-tolerated, and will improve abdominal pain in participants with non-constipation IBS. The primary aim is to evaluate the efficacy of rimegepant on abdominal pain scores in participants with non-constipation IBS. Secondary aims of this study are:

* 1: To describe the effect of rimegepant on rectal compliance in participants with IBS and chronic abdominal pain. * 2: To evaluate the effects of rimegepant on rectal sensation based on ascending method of limits and on graded rapid phasic distensions in participants with non-constipation IBS and chronic abdominal pain. * 3: To evaluate effects of rimegepant on overall colonic transit in participants with non-constipation IBS and chronic abdominal pain. * 4: To evaluate safety of rimegepant in participants with non-constipation IBS and chronic abdominal pain Methods: IBS-pain participants will be selected according to the Rome III criteria. Trial participants will continue to receive the same medical therapy throughout the baseline and treatment periods. The study design is a randomized, double-blind placebo-controlled trial of rimegepant at doses and route of administration approved by the FDA for the prophylaxis of migraine headache.

The trial period will consist of a two week run-in period, and 4 week treatment period. Participants will complete a daily diary regarding abdominal pain and stool consistency. They will also complete questionnaires studies of anxiety and depression and IBS-QOL.

An established and validated method using rectal barostat device will be used to measure rectal compliance and sensation. The standard scintigraphic method to measure colonic transit established in the Clinical Research Trials Unit (CRTU) at Mayo Clinic Rochester will be used to evaluate changes in colonic transit.

Anticipated results and Significance: Rimegepant, at doses and mode of administration approved by FDA for the prophylaxis of migraine headache, will be efficacious in the reduction of abdominal pain and rectal sensation in participants with non-constipation IBS and abdominal pain.

This study will provide an early signal of efficacy that may lead to future randomized, controlled trials.