Cautions Attached to Bowel Drug

WASHINGTON — Some users of the irritable-bowel treatment Zelnorm have suffered diarrhea so serious they require hospitalization, and four have died from an intestinal problem, the government said Wednesday.

The Food and Drug Administration emphasized that it had not proved a link between the intestinal condition, called ischemic colitis, and the drug.

But the agency ordered that a precaution about the intestinal condition go on Zelnorm’s label, along with a larger warning about severe diarrhea.

Irritable bowel syndrome is a disorder that gives millions of people, mostly women, abdominal pain and either severe diarrhea or constipation or both. Zelnorm is the only FDA-approved therapy for the constipation-causing form of the ailment. It is supposed to be used only by women.

The drug speeds the colon’s movement of stools, so diarrhea is a potential side effect. But the FDA has 21 reports of diarrhea so severe that it caused such complications as low blood pressure and fainting. Sixteen patients required hospitalization, said the FDA’s Robert Justice.

Zelnorm should be stopped immediately if patients get faint, the FDA said.

Since Zelnorm went on sale in 2002, the FDA has received 20 reports of ischemic colitis, plus three reports of a similar intestinal problem, Justice said. Fourteen patients were hospitalized. Four died, although they had other serious conditions.

The FDA advised patients who experience new or worsened abdominal pain or blood in their stools to stop taking the drug and call a doctor.