BACKGROUND

Alosetron is approved to treat women with severe IBS and diarrhea (IBS-D) who have failed standard therapy. In our study, we aimed to evaluate alosetron efficacy using new US Food and Drug Administration (FDA) endpoints and utilization in clinical practice.

METHODS

This prospective, open-label, multicenter, observational 12-week study evaluated women with severe IBS-D enrolled in the alosetron prescribing program. The coprimary FDA endpoints were changes from baseline in stool consistency and abdominal pain severity. Responders achieved a 30% decrease compared with baseline in weekly average of the worst abdominal pain in the past 24 h, and a 50% or greater reduction from baseline in the number of days/week with at least one stool of type 6 (mushy) or type 7 (watery) consistency. Secondary endpoints included changes from baseline in stool frequency, fecal urgency and fecal incontinence.

RESULTS

Enrolled patients ( = 192) were primarily White (90.6%), with a mean age of 44.5 years. Patient and physician rating of IBS severity was between moderate and severe (85.9% concordance, Spearman coefficient 0.429, < 0.0001). Alosetron 0.5 mg twice daily (82.8%) was the most common dosing regimen. A total of 152 alosetron-treated patients completed the study. Of 105 fully evaluable patients, 45% met the FDA composite endpoint responder criteria for ⩾50% of the study period. Improvements in all individual symptoms were statistically significant compared with baseline. There were no serious adverse events, cases of colonic ischemia, or complications of constipation.

CONCLUSION

In a clinical practice setting study, alosetron demonstrated treatment success using a rigorous FDA composite endpoint and also improved multiple other IBS symptoms, including fecal urgency and incontinence in women with severe IBS-D [ClinicalTrials.gov identifier: NCT01257477].