FDA Issues Warning About IBS Drug Zelnorm

Drug Associated With Serious Diarrhea, Reduced Blood Flow to Intestines

Medically Reviewed by Charlotte E. Grayson Mathis, MD on April 28, 2004
From the WebMD Archives

Editor's Note: In March 2007 the FDA asked Novartis -- the maker of Zelnorm -- to pull the drug from the market because of evidence that it raises the risk of heart attacks and stroke. But in July 2007 the FDA ruled that Zelnorm may be used by some patients in critical need of the drug who do not have heart problems.

April, 28 2004 -- The FDA today issued a warning associated with the irritable bowel syndrome (IBS) drug Zelnorm.

The FDA says Zelnorm has been associated with serious cases of diarrhea as well as instances of ischemic colitis -- a medical condition where blood flow is reduced to the intestines.

Zelnorm is a prescription medication for the short-term treatment of women with IBS whose primary bowel symptom is constipation. The FDA says it's adding this new drug information to ensure doctors and patients have the most current and complete information available when prescribing and taking Zelnorm.

The specific revisions include:

  • A new warning about the serious consequences of diarrhea associated with the medication

  • A new precaution about ischemic colitis and other forms of reduced blood flow to the intestines

  • Changes to side effects information section describing information gathered since the drug was approved in July 2002

The New Warning

In the new warning, the FDA states that serious consequences of diarrhea, including significant loss of fluid, low blood pressure, and episodes of passing out, have been reported in the clinical studies and during marketed use of Zelnorm. In some cases, these complications have required hospitalization for rehydration.

The FDA recommends that Zelnorm be discontinued immediately in patients who develop low blood pressure or passing out spells. Zelnorm should not be used in patients who are currently experiencing or frequently experience diarrhea.

The New Precaution

The FDA has also issued a precaution regarding the risk of reduced blood flow to the intestines, which may lead to inflammation of the intestines, called ischemic colitis.

In the new precaution, the FDA states that ischemic colitis and other, similar conditions have been reported in patients taking Zelnorm. Although this association has been observed, the FDA says that Zelnorm has not been proven to cause this effect. The FDA adds that clinical trials comparing Zelnorm to placebo in 7,000 patients for three months showed no cases of these events. This suggests the rate of such events is low, according to the FDA.

The agency says Zelnorm should be discontinued immediately in patients who develop symptoms of ischemic colitis, such as rectal bleeding, bloody diarrhea, or new or worsening abdominal pain. Treatment with Zelnorm should not be resumed in patients who develop findings consistent with ischemic colitis.

The FDA advises patients who get new or increased stomach pain or blood in their stools to stop taking Zelnorm right away and to immediately contact their doctor to determine if they may have a serious problem. In addition, the FDA advises patients to stop taking Zelnorm and to call a doctor right away if they experience diarrhea that leads to lightheadedness, dizziness, or fainting.

Zelnorm is the only FDA-approved prescription drug for the short-term treatment of women with irritable bowel syndrome whose primary bowel symptom is constipation.

Zelnorm increases the movement of stools through the bowels. Zelnorm does not cure IBS, nor does it treat the type of IBS where diarrhea is the predominant symptom. Zelnorm reduces pain and discomfort in the abdominal area and reduces bloating and constipation. The safety and effectiveness of Zelnorm in men have not been established.

Novartis, the maker of Zelnorm, is a WebMD sponsor.

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