Lubiprostone Effect on Gastrointestinal Tract Transit Times Measured by Smartpill in Patients With Chronic Constipation

Inclusion Criteria: * 18-65 years old * At least a 6 months history of constipation. Constipation defined as follows: * Less than three complete spontaneous bowel movements per week and one or more of the following: 1. At least 25% of stools are very hard and/or hard stools 2. Sensation of incomplete evacuation following at least 25% of bowel movements. 3. Straining on at least 25% of defecations. The above criteria are only applicable to spontaneous bowel movements. Patients who have no spontaneous bowel movements (bowel movements are preceded by laxative intake) are considered constipated and are eligible for this study. * For patients ≥ 50 years of age, normal colonic anatomy as documented by colonoscopy, double-contrast barium enema, or flexible sigmoidoscopy performed within the previous 5 years. Exclusion Criteria: * Pregnancy or lactation. * Subjects unwilling to practice adequate contraception throughout the period of screening through 14 days after the study termination. * Use of laxatives 3 days immediately prior to randomization (except fiber or bulking agents). * Use of any of the following drugs within 3 days prior to randomization: * Prokinetic agents (tegaserod, domperidone, cisapride, metoclopramide, erythromycin). * Medication containing opiates. * Anti-spasmodic (e.g., atropine, hyoscyamine, scopolamine, glycopyrrolate). * Use of illegal drugs * Regular consumption of 2 drinks of alcohol per day. * Chronic nonsteroidal antiinflammatory drugs (NSAIDs) use * Chronic use of H2 receptor antagonist or proton pump inhibitors (PPIs) within 14 days prior to screening. * History of gastric or duodenal ulcer, inflammatory bowel disease(IBD), or chronic non-ulcer dyspepsia. * Diabetes Mellitus (DM) type 1, Parkinson's disease. * Existence of any medical condition that requires chronic therapy. * Positive H. pylori serology * Chronic active diverticulosis