Alosetron relieves pain and improves bowel function compared with mebeverine in female nonconstipated irritable bowel syndrome patients

Background: Irritable bowel syndrome is one of the most common gastrointest inal disorders, yet no therapy convincingly controls the multiple symptoms of this syndrome. Aim: To compare the efficacy and tolerability of the new 5-HT3-receptor ant agonist alosetron and the smooth muscle relaxant mebeverine in a double-bli nd, multicentre. randomized trial. Methods: Six hundred and twenty-three nonconstipated females with irritable bowel syndrome were randomized to receive alosetron 1 mg twice daily (n = 319) or mebeverine 135 mg three times daily (n = 304) for 12 weeks. followe d by a 4-week post-treatment period. The primary efficacy end-point was mon thly responders for adequate relief of irritable bowel syndrome related abd ominal pain and discomfort (defined as patients reporting adequate relief o n at least 2 out of 4 weeks). Secondary end-points included assessments of bowel function, including urgency, stool frequency and stool consistency. Results: There were significantly more responders in the alosetron group co mpared with mebeverine at months 2 and 3 (P < 0.01). Compared with mebeveri ne, the alosetron group experienced significant decreases in proportion of days with urgency and mean stool frequency, and had firmer stools within 1 week of starting treatment. A similar proportion of patients reported adver se events in the two treatment groups. Conclusions: In nonconstipated female irritable bowel syndrome patients, al osetron is significantly more effective than mebeverine in improving sympto ms.