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Salix Drug Helps Irritable Bowel Syndrome

Salix Drug Helps Irritable Bowel Syndrome [The News & Observer, Raleigh, N.C.]

From News & Observer (Raleigh, NC) (January 6, 2011)

Jan. 06--A 14-day round of antibiotic made by a Triangle drug company appears to provide months of relief from some of the worst symptoms of irritable bowel syndrome, researchers announced today.

The antibiotic, which goes by the brand name Xifaxan and is manufactured by Salix Pharmaceuticals of Morrisville, is the first therapy for IBS that offers prolonged benefit -- a feature sufferers hailed as a breakthrough.

Salix is seeking U.S. Food and Drug Administration approval to market the antibiotic for IBS, and a hearing is slated for March. The antibiotic is already approved for traveler’s diarrhea and a rare liver condition.

If approved for IBS, Xifaxan would likely be Salix’s top seller and one of the biggest products among any of the Triangle’s drug-development companies.

Irritable bowel syndrome is one of the most commonly diagnosed problems in the United States, and Salix estimates it could reap $2.5 billion a year in sales if the FDA allows it to market Xifaxan to treat IBS.

The syndrome, afflicting up to 35 million adults in the United States, is marked by varying levels of pain, bloating and either diarrhea or constipation. For those with severe symptoms, the disorder can be debilitating.

Despite the study showing Xifaxan’s success -- results were published today in the New England Journal of Medicine -- the antibiotic doesn’t work for everyone with IBS. It was tested on patients with diarrhea, not constipation, and even then, only 41 percent reported relief. By comparison, 32 percent of study participants taking a dummy pill also reported improved symptoms.

In addition, the drug is pricey, costing up to $500 for the two-week regimen.

Still, patients welcomed a potential new treatment for a disorder that has few effective remedies.

"It was a godsend to me, even though it was expensive," said David Brown, a former Danville, Va., fireman who retired on disability almost five years ago when his irritable bowel condition grew so severe he was in constant distress. Brown participated in the clinical trial testing Xifaxan at UNC-Chapel Hill.

Doctors don’t know what causes IBS, but the success of the antibiotic strongly suggests a bacterial trigger in some cases, said Dr. Yehuda Ringel, an associate professor of medicine at UNC-CH and co-author of the Xifaxan report in today’s journal.

"How does it work? We have no idea. We can speculate," Ringel said of the drug’s effect. " ...When [intestinal bacteria are] targeted, we get beneficial effect. And the effect lasts for 10 weeks, maybe more. That means we are not targeting only symptoms, but maybe the underlying cause."

More research needed

Ringel said more work is needed to figure out what species of bacteria may be the culprits and why they suddenly incite intestinal mayhem.

In addition, he said, more studies are needed to see whether Xifaxan can be used repeatedly when symptoms return, and whether it works among the other half of IBS patients who suffer constipation.

Bill Forbes, executive vice president and chief development officer of Salix, said the company may conduct further tests to explore how long it takes for patients’ symptoms to return and how well patients respond to repeat treatments.

One of the benefits of the therapy, Ringel said, is its targeted approach. The molecule is too large to be absorbed and circulated throughout the body, so it can concentrate its firepower on the bacteria in the intestines. Whatever’s not used in the gut is excreted, leaving most patients with few side effects.

New therapy welcome

Brown, the Virginia patient, said the only effect he had from taking the pill was an improvement in his symptoms -- a major plus over other treatments he has tried. He said another antibiotic caused him terrible pain.

Other IBS treatments have had safety concerns. A drug called Lotronex, manufactured by GlaxoSmithKline, was temporarily pulled from the market over reports it was linked to colitis and even death. It is now available only to women who have chronic IBS with severe diarrhea.

Forbes, the Salix executive, said a new therapy for IBS has been sorely needed.

"With IBS, ... no one really understands why patients have symptoms," Forbes said. "It becomes a condition that is diagnosed by exclusion. But the economic costs rank right up there with the worst medical conditions there are."

Staff writer David Bracken contributed to this report. or 919-829-4882

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Posted: January 2011