Lubiprostone is a locally acting chloride channel activator with a similar mechanism of action to bulking agents and osmotic laxatives on intestinal fluid. Lubiprostone increases intestinal fluid volume and motility, resulting in stool softening and ease of passage. Although the U.S. Food and Drug Administration approved the use of lubiprostone in January 2006 for chronic idiopathic constipation, no studies in patients with cancer have been published.