Tegaserod Approved for Constipation-Predominant IBS in Women

Deborah Flapan

September 11, 2002

Sept. 12, 2002 — The U.S. Food and Drug Administration (FDA) has approved tegaserod maleate (Zelnorm) for short-term treatment of irritable bowel syndrome (IBS) in women whose primary bowel symptom is constipation. Tegaserod, a selective serotonin type-4 receptor partial agonist, increases motility of the gastrointestinal tract. The first of its kind for this indication, tegaserod does not treat diarrhea-predominant IBS. In addition, because the study on which the FDA based its approval only involved women, the drug's effectiveness in men has not yet been established.

The FDA approval was based on results from three 12-week, randomized, double-blind clinical studies. A total of 2,470 women with at least a three-month history of IBS symptoms of abdominal pain, bloating, and constipation received 6 mg of tegaserod twice daily or placebo. To measure the drug's efficacy, study subjects in both groups were asked to rate their overall well-being, symptoms of abdominal discomfort and pain, and altered bowel habits on a weekly basis throughout the study.

The rate of favorable response was 5% to 11% higher than placebo in all three studies. Because the response difference between the two groups declined at the end of the first month, the drug's effectiveness may decrease during longer-term treatment than 12 weeks.

The most frequent adverse event associated with tegaserod was diarrhea (9%) compared with 4% for placebo, but it usually resolved without discontinuation of the therapy. Patients receiving tegaserod also required a proportionally slightly higher number of abdominal operations (0.3%) compared with 0.2% for the placebo group. However, tegaserod was not established as the cause of the high proportion of surgeries.

Contraindications for tegaserod include severe renal impairment; moderate or severe hepatic impairment; a history of bowel obstruction, symptomatic gallbladder disease, suspected sphincter of Oddi dysfunction, or abdominal adhesions; and a known hypersensitivity to the drug or any of its excipients. Tegaserod should not be given to IBS patients with diarrhea, and the drug should be discontinued immediately in those who experience new or increased abdominal pain.

Reviewed by Gary D. Vogin, MD


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