Irritable bowel syndrome patients clearly exhibit disordered motor patterns throughout the gastrointestinal tract, particularly in the small and large intestines. Although past and current research points to an association between irritable bowel syndrome symptoms and abnormal contractility, a causal link has not yet been definitively established. Because abnormal contractility has not yet been clearly linked with symptoms, and because irritable bowel syndrome patients often experience pain during normal motor activity, researchers also have looked at a hyperalgesic (heightened sensitivity to pain) model to explain abdominal pain in irritable bowel syndrome.
Irritable bowel syndrome (IBS) is a very common disorder characterized by frequent diarrhea or alternating bouts of diarrhea and constipation. It is more than twice as common in women as in men. In February 2000, the FDA approved the drug Lotronex (alosetron) for the treatment of women whose primary irritable bowel syndrome symptom is diarrhea.