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Irritable Bowel Syndrome (IBS) Health Center

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Zelnorm Deemed Safe for IBS Constipation

Watchdog Group Still Worried, but GI Docs Happy


"There is nothing in these data to support the idea that this [ovarian cyst] is a signal that such problems happen with increased frequency in [people who take] Zelnorm," Tougas tells WebMD.

The data show nothing because the study was poorly designed, counters pharmacologist Elizabeth Barbehenn, PhD. Barbehenn is a former FDA scientist who now serves as a research analyst for Public Citizen.

"It's a big joke," Barbehenn tells WebMD. "There was no control group, so you could say anything you want. Half the people dropped out before the study ended. And there was no protocol for whether the drug caused problems. They let the investigators just decide whether they thought adverse events were related to the drug."

Private practice gastroenterologist and Johns Hopkins clinical instructor James Novick, MD, headed a major clinical trial of Zelnorm. He says ovarian cysts simply aren't a real problem for people taking Zelnorm.

"As far as I understand, the ovarian cyst concern holds no water whatsoever," Novick tells WebMD. "The most common side effect was headache -- 3% more in [Zelnorm] patients than in placebo patients. Then 5% of patients get what they consider to be diarrhea, mostly in the first couple of weeks of treatment. Best of all, there is no interaction with other drugs, not even SSRI antidepressants. That doesn't seem to happen, which is a real godsend."

Novick notes that the only other concern with Zelnorm was that several patients taking the drug needed gallbladder surgery.

Initially there was a scare the drug might be causing gallstones symptoms -- that was the data that led the FDA to slow approval, he says. "That was far more troubling than the ovarian cyst worry. But now it appears the drug has no effect on the gallbladder. The FDA had a look at the data before approving the drug, and they were happy enough."

Doctors who treat IBS patients are optimistic but cautious about using Zelnorm, says gastroenterologist Eri Ehrenpreis, MD, director of the gastroenterology fellowship training program at the University of Chicago.

"For the GI doc on the street, the impression has been positive," Ehrenpreis tells WebMD. "Everybody is a bit gun-shy about using serotonin-manipulating drugs. Remember, with Lotronex we learned of the danger only six months after approval. But I think this is a safe drug. If you look at these studies on IBS patients, these are really very intensively conducted trials. There are hundreds and hundreds and hundreds of patients who were treated."

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