Phase 2 Study of MD-1100 Acetate on Gastrointestinal Transit in Patients With C-IBS

* The primary objective of this trial is to compare the dose-ranging pharmacodynamic effects of orally administered placebo, and 100 and 1000 ug qd of MD-1100 Acetate on gastrointestinal transit in patients with C-IBS. * The secondary objectives of this trial are: 1. To compare the dose ranging pharmacodynamic effects of placebo, and 100 and 1000 ug MD-1100 Acetate once daily on time to first bowel movement after first drug intake. 2. To describe and summarize the effects of placebo, and 100 and 1000 ug MD-1100 Acetate once daily on stool frequency, stool consistency, ease of passage and sensation of incomplete evacuation during the Treatment Period relative to Baseline.