Current mechanisms of action in treatment of chronic constipation and irritable bowel syndrome

Patients with, chronic constipation and irritable bowel syndrome (IBS) have a variety of potential treatment options. Treatment typically begins with lifestyle changes and fiber supplementation. The predominant lifestyle changes are alteration of fluid intake, dietary modification, and physical activity. Laxatives constitute the second line of therapy. Patients can avail themselves of various emollient, osmotic, and stimulant laxatives. Among all the laxative agents, the strongest supporting evidence is for lactulose and polyethylene glycol. These conventional therapies have highly variable rates of therapeutic success. Most patients cope with their symptoms and are less than completely satisfied with therapy. Newer therapies have provided additional options that may help improve symptom relief and patient satisfaction. The 5-HT4 serotonin agonist tegaserod has demonstrated efficacy for chronic constipation and constipation-predominant IBS and is approved for treatment of men and women with chronic constipation and for women with IBS. The chloride channel activator lubiprostone recently was approved for treatment of constipation in men and women. The 5-HT₃ antagonist alosetron has approval for treatment of diarrhea-predominant IBS in women. A host of investigational agents are in various stages of evaluation and clinical development, many of which represent new approaches to treatment of chronic constipation and IBS.