Chronic idiopathic constipation (CC) and irritable bowel syndrome (IBS) with constipation-predominant (IBS-C) are common conditions in North America and often difficult to treat effectively. The prevalence of IBS is about 11%, of which, IBS-C accounts for 22% to 35%. Lubiprostone is one of two chloride channel activators approved for the treatment of IBS-C.