Effects of Lubiprostone on Gastrointestinal Transit & pH in Irritable Bowel Syndrome (IBS) With Constipation

Study Summary

Irritable bowel syndrome (IBS) is a common disorder which presents with abdominal pain or discomfort in association with altered bowel habit. IBS is further subcategorized as three types according to the predominant bowel movement pattern: IBS with constipation (IBS-C), IBS with diarrhea (IBS-D), and mixed-IBS (IBS-M). The exact causes of IBS remain incompletely understood, but proposed mechanisms include abnormal motility, visceral hypersensitivity, abnormal brain-gut interactions, psychological distress, and altered GI tract motility. Lubiprostone, a novel drug that works by activating the colonic Chloride channel type 2(ClC-2), has been approved for use in patients with chronic idiopathic constipation and recently approved for the treatment of IBS-C in women aged 18 and older. By activating the ClC-2 chloride channel in the colon, lubiprostone allows more fluid secretion into the intestinal lumen which leads to softer stool consistency. In phase III clinical trials, patients with IBS-C receiving lubiprostone have reported improvements in many symptoms such as abdominal pain and constipation. However, there is limited physiologic data to explain how exactly lubiprostone improves IBS-C symptoms. The Smartpill is a novel non-digestible capsule that is capable of measuring intraluminal pH, pressure, and temperature in the gastrointestinal (GI) tract. Smartpill has been shown to accurately measure whole gut as well as regional (i.e. stomach, small bowel, colon) transit time. The primary aim of this study is to determine the effects of lubiprostone on whole GI tract transit, colonic transit, motility, and intraluminal pH in patients with IBS-C through evaluation with the Smartpill. The investigators propose to study the effect of lubiprostone vs. placebo on these parameters, and secondarily to evaluate changes in these parameters with differing doses of lubiprostone. The investigators hypothesize that lubiprostone will increase whole GI and colonic transit compared

Primary Outcome

Change in gastric emptying time, small bowel transit time, colon transit time and whole gut transit time measured in hours based on a measurement done at baseline and then again at 3 weeks into the intervention within each treatment arm

Interventions

• DRUG Placebo
• DRUG Lubiprostone
• OTHER Smartpill wireless motility capsule