Food and Drug Administration
U.S. Department of Health and Human Services
Public Health Service 5600 Fishers Lane Rockville, MD 20857
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T00-10 Print Media: 301-827-6242 February 9, 2000 Consumer Inquiries:888-INFOFDA
IBS is a functional abnormality of the gastrointestinal tract that is estimated to affect up to 15% of the US population. People with this condition experience chronic or recurrent abdominal pain, irregular bowel movements including diarrhea and constipation, and the sudden, urgent need to go to the bathroom. It is three times more common in women than men.
Like existing IBS therapies, alosetron treats the symptoms associated with the syndrome. Although how the drug works is not completely understood, alosetron slows intestinal movement and may provide relief by targeting the underlying neurological activity associated with the condition.
FDA based its approval on the results of two 12-week double-blinded, placebo-controlled clinical trials. A total of 1273 non-constipated women, who met specific pain and stool consistency criteria, were enrolled.
In each study, alosetron was significantly more effective than placebo in providing relief from IBS pain and discomfort and in reducing the percentage of days with urgency. Treatment with alosetron also resulted in firmer stools and a significant decrease in stool frequency.
Significant improvement of symptoms typically occurred within the first weeks of alosetron treatment and persisted throughout the 12 weeks of the studies. Upon discontinuance of alosetron, symptoms returned.
The most frequent adverse event reported by study participants taking alosetron was constipation, which in many cases required interruption or discontinuation of treatment. Occurrences of constipation were generally mild to moderate in intensity and transient in nature. The drug's label recommends managing this adverse effect by temporarily stopping drug treatment and giving customary care, including laxatives and fiber.
In addition, four study patients taking alosetron developed acute colitis, a potentially serious inflammation of the large intestine. This condition resolved without serious consequences when the drug was discontinued. Although a causal relationship between the drug and this adverse effect has not been established, further assessment is underway.
Health care providers are advised to interrupt treatment immediately and to evaluate promptly patients who have symptoms of acute colitis such as bloody diarrhea and sudden, significant worsening of abdominal pain. The FDA encourages health care providers to report any such cases to FDA's MedWatch program by calling 1-888-INFO-FDA or by logging onto FDA's web page, www.fda.gov/medwatch.
Alosetron has not been shown to be safe and effective in men, and its use in men is not recommended.
Today's decision follows a November 1999 recommendation for approval by FDA's Gastrointestinal Drugs Advisory Committee.
Alosetron will be marketed as Lotronex by GlaxoWellcome of Research Triangle Park, NC.