Efficacy and safety of alosetron in women with irritable bowel syndrome: arandomised, placebo-controlled trial

Background Irritable bowel syndrome (IBS) is a common gastrointestinal diso rder with symptoms of abdominal pain, discomfort, and altered bowel functio n. Antagonists of the type 3 serotonin receptor (5-HT3) have shown promisin g results in the relief of IBS-associated symptoms. We aimed to confirm the se findings by doing a randomised, placebo-controlled trial. Methods We studied 647 female IBS patients with diarrhoea-predominant or al ternating bowel patterns (diarrhoea and constipation). 324 patients were as signed 1 mg alosetron and 323 placebo orally twice daily for 12 weeks, foll owed by a 4-week post-treatment period. Adequate relief of abdominal pain a nd discomfort was the primary endpoint; secondary endpoints included improv ements in urgency, stool frequency, and stool consistency. Analysis was by intention to treat. Findings 79 (24%) of patients in the alosetron group and 53 (16%) in the pl acebo group dropped out. The difference in the drop-out rate between groups was mainly due to a greater occurrence of constipation in the alosetron gr oup. A greater proportion of alosetron-treated patients than placebo-treate d patients (133 [41%] vs 94 [29%], respectively) reported adequate relief f or all 3 months of treatment (difference 12% [4.7-19.2]). Alosetron also si gnificantly decreased urgency and stool frequency, and increased stool firm ness. Constipation occurred in 30% and 346 of patients in the alosetron and placebo groups, respectively. Interpretation Alosetron was well tolerated and clinically effective in all eviating pain and bowel-related symptoms in this population of women with I BS.