Over-the-counter (OTC) sales of laxatives generate $400 million annually in the United States. Because approximately 30% of healthy elderly people use laxatives regularly, the elderly contribute substantially to this $400 million market. Indeed, laxatives are second only to analgesics as the OTC medications most widely used by the elderly. Many of these people do not regard themselves as constipated, but simply in need of a regular purgative. Many of those people who do regard themselves as constipated do not have true constipation (defined as fewer than three bowel movements a week, straining at stool, or both).