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Paxil May Help Irritable Bowel Syndrome

<P>Antidepressant Has Strong Effect in Those Not Feeling Fit After Fiber</P>

When Fiber Fails continued...

At the end of the 12 weeks, patients could choose to continue on their medication -- without learning whether they were taking Paxil or placebo. In the Paxil group, 84% wanted to continue. Only 37% of the placebo group chose to continue treatment. After six months, 76% of the Paxil group and 36% of the placebo group were still taking their pills.

These findings impress Reza Shaker (sha-CARE), MD, chief of the division of gastroenterology and hepatology at the Medical College of Wisconsin.

"It is an interesting study, and I think it is a real effect of Paxil they are seeing," Shaker tells WebMD. "I like this study because it is independent -- the drug companies did not pay for it -- because it was randomized, and because it has a six-month follow-up. It's a relatively small number of patients, but still it is very promising that in a subgroup of IBS patients, SSRI antidepressants may be helpful."

Irritable bowel syndrome, Shaker says, is not a single disease but may arise from several as-yet-unknown causes. By treating only patients who did not respond to fiber, he suggests, Arnold's team may have found a way to identify a group of patients with the kind of irritable bowl syndrome most likely to respond to antidepressant treatment.

"Obviously we should not take this study as encouragement to give this drug to everybody," Shaker warns. "It must be used in a select group of patients."

Depressed Intestines?

Why would an antidepressant work in people who aren't depressed? Older tricyclic antidepressants are often used to treat irritable bowel syndrome. But newer antidepressants -- the SSRI class, like Paxil -- specifically act to increase the action of serotonin, a chemical messenger.

The drugs are designed to increase serotonin levels in the brain. But that's not the only place serotonin is found.

"Here's why I think Paxil works for irritable bowel: 95% of the serotonin in the body is in the intestine," Arnold says. "I think it is doing something to the nerves in the gastrointestinal tract."

Shaker notes that people with irritable bowel syndrome tend to have problems with the way sensations arise in the gut, the way these sensations travel through the nerves to the brain, and/or with the way the brain processes these signals. He agrees that Paxil and other SSRIs are likely to affect this process.

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