Alosetron-New Drug for Irritable Bowel (cont.)
Irritable Bowel Syndrome (IBS) is a complex gastrointestinal disorder of unknown cause that afflicts approximately one out of every five adult Americans and three times as many women as men. The symptoms of IBS include abdominal pain, bloating, mucous in stools, and diarrhea and/or constipation. Commonly, more than one symptom is present. Psychological features such as depression, anxiety or stress may accompany IBS. There are no tests for IBS. In fact, the diagnosis of IBS is based on the presence of compatible symptoms and normal tests for gastrointestinal disorders (for example, x-rays and endoscopic examination of the intestines). It is theorized that the cause of IBS is dysfunction of intestinal nerves and/or muscles.
Since the underlying cause of IBS is unknown and, therefore, not treatable, the focus of treatment in IBS has been the management of symptoms. An assortment of drugs including antidepressants, anti-spasmotics (muscle-relaxers), anti-diarrheals, and laxatives have been used as well as dietary changes (e.g., high fiber, low fat). Psychiatric testing and treatment also has been employed.
Alosetron (Lotronex) is the first drug to be approved specifically for IBS. Two 12-week studies involved more than 1,200 women with IBS in whom diarrhea was a predominant symptom. The patients were treated for three months with either alosetron or placebo. Each week the patients were asked if the drug they were taking had given them adequate relief from abdominal pain and discomfort. Adequate monthly relief was defined as at least two weeks out of every four consecutive weeks with adequate relief. Forty-one percent of the patients receiving alosetron experienced adequate monthly relief for each of the three months (12 weeks) of the studies while only 30% of the patients receiving placebo experienced similar relief. Patients taking alosetron also had fewer days with a sense of urgency with their stools (decreasing from 7 out of every 10 days to 4 out of every 10 days), fewer daily stools (decreasing from three to two per day), and firmer stools. The most common side effect with alosetron, constipation, was seen in approximately one-third of patients and caused nine to ten out of every 100 patients to stop taking the drug either for a short time or indefinitely.