http://www.ivillagehealth.com/news/topnews/content/0,,418445_582458,00.html

New drug approach to irritable bowel syndrome

By Maggie Fox, Health and Science Correspondent

Last Updated: 2003-05-29 17:00:25 -0400 (Reuters Health)

WASHINGTON (Reuters) - A drug currently used to treat alcoholics and drug overdoses may also offer relief in a surprising quarter -- people with irritable bowel syndrome, corporate researchers said on Thursday.

A small trial of 50 patients with the painful disorder showed that three-quarters of them got relief from the drug, known best as naltrexone, the company said.

South San Francisco-based Pain Therapeutics Inc. said tiny doses of naltrexone, which is available generically, eased the bloating, pain, constipation and diarrhea that mark irritable bowel syndrome (IBS) in both men and women.

"Seventy-six percent of patients on our drug had a positive response," Remi Barbier, president and chief executive officer of Pain Therapeutics, said in a telephone interview.

One in five Americans has IBS, making it one of the most common disorders diagnosed, according to the National Institute of Diabetes and Digestive and Kidney Diseases. More common in women than in men, it is not a true disease and does not cause disease, but creates a great deal of discomfort and distress.

Barbier said judging the effectiveness of the drug is subjective. "It's like antidepression drugs or pain drugs -- yes, it is subjective, but believe me, the symptoms of IBS are so severe that if you are better, you know it," he said.

Two drugs are approved by the U.S. Food and Drug Administration (FDA) to treat IBS -- GlaxoSmithKline's Lotronex and Novartis AG's Zelnorm. But they are only approved for women and for short-term use.

Experts also recommend stress-reduction and relaxation measures, such as meditation, walking, yoga and getting enough sleep, as IBS seems to be aggravated by stress.

Naltrexone, which Pain Therapeutics is testing under the name PTI-901, takes a new approach to treating IBS.

"The traditional view of IBS is that the flusher is broken -- it is either flushing too quickly or not quickly enough, causing diarrhea or constipation," Barbier said.

"We disagree with that point of view. We don't think the flusher is the problem. We think it is an imbalance of opioids in the gut. We provide the patient with an external source of opioid antagonists to restore bowel function."

The current, Phase II study was designed mostly to assess safety, and the company now plans to start a larger, Phase III efficacy trial -- the last step before seeking FDA approval.

"We believe a safe and effective drug to treat both men and women who suffer from IBS represents a $1 billion market opportunity in the United States alone," Barbier said.

Barbier said scientists working with his company stumbled on the opioid-IBS connection when they compared notes on patients who had overdosed on morphine or heroin, both opiate drugs.

"Patients who overdose on morphine lean over and hang on to their stomach," Barbier said. "The light bulb went on. Maybe opioid withdrawal and IBS are one and the same symptoms, which is an imbalance of opioids in the gut."

Copyright 2002 Reuters.